Dude you need a medal for how consise and accurate your information is here! Perfectly broken down so that even laymen could grasp the workings well done sir
Hello My name is Jani Soini and I'm from Finland and I removed the restriction from my exhaust pipe. Now I have to change the main jet to a bigger one but don't know what sice... My friend's say that if I don't change it to a bigger one the motor might be ruined. Can you please please help me!?? 😯 I have a sym Jet euro x 50cc scooter. Can you tell me what size pilot jet is good for my bike ? I would be forever grateful if??
Best way I’ve found to help with this, set the tuning back to factory tuning(usally 3 full turns out for both air and gas screws) then give it a quarter turn back in on the gasand it should be enough to start the bike until you can actually tune it. It’s just 50cc that are an ass because of how exact you have to be sometimes
Man, this is the best video I’ve seen on how to set the idle speed, you have saved my life. I’ve been trying for weeks to find someone to teach me and no one really knows how to properly do what you have just explained, not even the so-called experts. Thanks to your video now I know how to do it, I can’t wait to go tomorrow and set my DD2 rotax carburetor and FINALLY be able to drive like it’s supposed to. One again, THANK YOU SO MUCH 🙏👍👍👍
great video and breakdown. my kids little atv was idling rough, thumping...and backfiring every so often. Adjusted the idle and richened it up a little bit, idling like new, smooth, and no backfires. Thank you!
Thank YOU!!!!...not TOO technical; straight forward. I've owned 70's thru 90's motorcycles(n cars) but these tiny carbs are SO sensitive--the lazy part of me wanted to just buy a NEW carb online without manual choke...but THIS video gave confidence that all these giant BOOK manuals have given me (tiny print; way too general, etc..)
im working on an '85 Honda Aero 80cc thats been in an attic since 1987 with a full tank of gas. These past few days have been a nightmare! Turns out, they havent made gas tanks for this scoot since '87, and this is too far beyond repair. Ive worked on tons of Chinese scoots using your help. Now, I can thank you for helping with this one. The air restrictor was stuck wide open due to some gunk build up even after ive cleaned and rejetted. i finally just looked throught the dang thing after this video and saw it stuck wide open. Its too late to try and get it running tonight with the kids being asleep, and I have to work all day tomorrow. Now its going to be on my mind all day! Thanks AGAIN!
This is great, similar principles to italian scooters i.e. derbi model with piaggio motors. My Scooter was running way too rich as indicated by the soiled spark plug. The scooter recently developed a significant vibration at about 1/4-1/2 throttle and at idle. After turning the idle mixture screw out about 8 full turns, the scooter idles much more smoothly, doesn't lag on take off and doesn't vibrate anymore. It actually has never ran this smooth. Great explanation of the process and how the carb works! Thank you. 2007 Derbi Atlantis Bullet 49 cc with piaggio engine.
Be careful. If turned out too far the screw gets loose and can loosen further with vibrations and end up falling out. Replace the idle/pilot jet if necessary to make sure the screw can be adjusted without it being too loose.
I just got a 450$ Chinese scooter and man the carb is giving me a real hard time I ordered a new one after trying to clean the old one several times but your videos have helped so so much thank you
THANK YYYYYOOOOOUUUUU!!!!!!!!!!!!!!!!!! I been looking alllll day to c what this 2 screws do to my mini bike jeez. Finally to the point. Great no no no awesome vid bro thanks for the info I DEEPLY APPRECIATE IT P.S. I gave u a 👍🏻 u more than deserve it
Thank you! I've been having a carb issue(keihin pb16/kymco like 50 2t) & took it apart for the first time today. At a point when changing the main jet (w/out fully removing the carb from the engine) I 'adjusted' the float w/out realizing. I put the carb back together properly, but the engine isn't firing (w/good spark and compression). A suggestion has been made to alter the idle mix since my plug is wet. My carb is different than this one, but it is very helpful to get a visual & explanation.
I've looked up how to adjust mixture screw 300 times in the last week no one said anything about trying to get it to idle as high as you can with the mixture screws no wonder why I can't get my sled mixture screws right now tomorrow I can go out there and turn them one and a half out and then start turning them until I can get my highest idle and then back off my idle screws until I'm at my preferred RPM idle thank you !!!!!!!!!!!!!!!!!!
I need a float for this exact carburetor, mine is off a Bombardier DS90 2stroke but they discontinued the parts. Where can I find aftermarket parts??? Or can you give me a part number for this?
Take a look at PartsForScooters part number 161-214. There used to be some rebuild kits around if you searched for something like "polaris 90 carburetor rebuild". You can look in a Polaris parts manual for an outlaw/sportsman/predator 50-90 and see if they have a part you can get.
90GTVert you nailed it with the Polaris 90 recommendation! Found a part number through the Polaris Predator 90 diagram! www.partzilla.com/catalog/polaris/atv/2004/predator-90-a04ka09ca/carburetor-cb Thanks again, very helpful!
This has made a lot of sense because soon as the vacuum pipe is on it doesn’t start use a vacuum pump tester it works I’m guessing ether the carb or vacuum tap isn’t working properly
Finally a video on adjusting screws. What is usually stock on a carb just roughly as I’ve rebuilt my carb which was all blocked up with the wrong adjustments?
1.5-2 turns out is usually a decent starting point for the mix screw. For the idle speed, you can make sure it's raising the slide a little and then you'll figure that one out quick enough when it's running.
I"m in the middle of cleaning up my cousin kids atv's.. It missing hose's and out of adjustment . This video explains a lot. But one thing i am not sure of it what that Barb fitting above the idle screen used for?
How far should the Idle screw be open, given that its a first start after the carb was off for cleaning? What causes the engine to die out when I touch the throttle? Sorry if it sounds like a silly question, but I'm still at the "start it up, let it warm up, take it for a spin" part.
About 2 turns for a starting point on the mix. Look at the slide in the carb and turn the idle speed screw till it's just barely open. May have to work the throttle a bit to get it started and turn it in more, but that's better than having it take off when you start it. You may have the wrong mix settings or needle setting or perhaps something is still clogged in there. Air box should be installed if not already.
***** hey I have a 2 stroke I just bought and and I replaced the air filter and noticed some oil in the card laying in a crevice by where the air filter connects. Also it smokes quite a bit even after it starts and runs for a bit. Stock muffler restricts the power a ton and runs perfect with it just slow when I put the performance muffler on it runs spectacular but after three minutes when giving it gas it feels like it's missing and won't pick up and go then out of nowhere takes off like a a bat out of hell again and then eventually bogs out and stalls.
You probably need to tune the carb for the aftermarket pipe with a larger main jet. Could be just low quality oil making it smoke, unless it's a new problem with a scoot you've had for a while.
Muito obrigado pela super dica,eu tenho uma yamaha Jog 50cc e demorei muito pra encontrar o ponto certo da regulagem do Ar e da marcha lenta,agora deu certo 😘👍🏼👌🏼 Tank You Man 😎👍🏼
Hi this was very helpful I just brought a aeon mini kolt with a oil injection all pipes missing and not sure where to connect the oil was wondering if you could give me some advice thanks
In this video, the oil injection port is the one above the idle speed screw. You'll often see that it's a barb with a large base, because many (not all) house a check valve with a ball and spring in there.
Hope I get reply so once I go over 2& half turn I get the best idile any more there’s no change so do I stopwhere the best idile is.... Are trying to say that you should be able to screw out for the best idile and before the screw pops out you should get a drop in revs as well ?????
My revs at idile on mixer screw is two and half turns out the revs increase at at 1/half between one and half and two and half these no difference so where do I leave it
What if turning the air screw all the way in or all the way out makes no difference at all? I bought a new carburetor which is sold for my bike model and it is supposed to work out of the box. And indeed it works, idle, half throttle and full throttle. But I cant set the air screw cause it looks like it does nothing.
@@49ccscoot using it today I found out that it works pretty rich. Because when I turn it on and rev it, lot of smoke is coming out of the exhaust. Also I have to give it throttle in order to turn on. It does not turn on by pushing only the starter button. The carb is a brand new 17mm chinese gurtner clone. Replaced a dellorto phva 12.
@@cabrinhaGR So much for "supposed to work out of the box". Possibly too large of a main jet and pilot jet.I'd prob start with main jet swaps to see if that helps it all around.
@@49ccscoot main jet comes into play when throttle is fully open, right? And when I am on wot everything is ok. In fact everything looks ok in the whole spectrum, from idle to wot. The only problem is that the air screw does not affect mixture (no rise or fall of rpm, no engine stall etc.).
@@cabrinhaGR It does. Large main jet could make everything bad, but if it's good everywhere else then prob don't start there. New or not, I'd clean the carb. I don't trust Chinese stuff to be setup properly or free of debris.
I lost the pilot screw when riding a Honda Spree years ago. Somehow it kept going and got me home. Same for when one of the carb bolts fell out and I had to zip tie the carb on to get me home.
+Guajiro Konn You've pressurized the cases (about 6psi) and made sure pressure does not escape? Checking with propane, water, carb cleaner etc... for intake leaks is not always effective on a 2T. Reeds in good shape? Float height set properly?
hey I just picked up a eton beamer 2t and it idles too high even with the idle speed screw at its lowest setting, would i have to adjust the mixture setting? or is it a different problem?
Make sure the cable isn't pulling the throttle open. There should be adjusters. One at the handlebar and one at the carb. If there isn't a small amount of slack it'll hold the throttle open. Could be that you need to adjust in more fuel or have an air leak as well.
Yup thank you officially I just adjusted both my screws and it’s running perfectly thanks bro really appreciate it wish I could give u more 👍🏻because I would
To adjust my bike, do I have to adjust first the idle speed, and then the mixture screw?? Then if the engine goes to fast I will have to turn again the idle speed? and then the mixture again?? or when the mixture is done good it doesn't have to be touched again?? thank you so much
Would u mind explaining the rolling wrench pwk 21mm carb that's said to be for the bbk qmb39. Has a blue an red knob . Blue on left side an red on right side an both are on the air filter end of carb
No exp. Just looked at pics. Blue is idle speed. Guessing the knob will be choke. Idle mix screw should control air on the PWK. Looks like a $25 AliExpress carb to me, with extra decals.
Great Info!! thanks a lot!! what about if you get it good, but on WOT from standing point she bogs and spits?? I had it ok but the engine was flooding. I took out the carb and cleaned it, and this tarted after i installed it back in. Just cant get it right this time. Any tips on what might be the problem?
Give it a try since it can be quick and simple if the carb is easy to access. If it's RPM dependent and not throttle position dependent though, you may have something else going on... like a clutch issue for example.
Do you know what set of jets this carb would take? I have a 50cc Rivera Jog and the carb looks exactly like this one. Thanks in advance! This was an awesome video!
They're Mikuni VM11/22 jets or I've used Dellorto 6mm jets in them before. Whatever you use, get a set of all one brand and type. Don't mix and match or sometimes the sizes aren't accurate to each other. Name brand preferred... Mikunu, Polini, Stage6, and so on.
There's usually a spring under the mixture screw, but it's not generally visible without taking it out. The idle screw often has a spring under it that can be seen without any disassembly.
If your just starting out, as long as it's not fouling you're OK. If you get to fine tuning, especially higher throttle settings, then maybe put a new plug in.
@@49ccscoot wow thank you man for responding so quickly. It's not fouling the plug, just kind of gutless. The other Eton viper is much snappier. Both are Eton Viper 90s. Getting ready to sell them. Kids out grew them and want someone to enjoy like we did. Thx again.
hi, thanks for the video. I am busy rebuilding a DINLI JP 502 and bought the exact carb, but are not sure about the hose connections? I only have the fuel hose and a thin hose coming out of the engine. There is however 4 hose connection points on this carb. I understand some is vacuum and should be kept open, just not sure which is which. Have you got a diagram of it. All the manuals of Dinli JP 502 I found on the internet is "shadowed" and I can not make out anything on it. I normally fix mowers and whipper snippers. This is my first quad job...
Adjust mixture until there is no lag or hesitation when I goose the throttle a little? How can I make sure it's not too lean or rich, as I've got it idling pretty good, now. Thank you for your time, Bro'.
Hello Thank u for ur efforts to explain such a complex topic so practically. can u pls guide me on how to get the max pick up on my Yamaha, 2 Stroke RX100 92 model? I have put new clutch plates, new piston, rebored the block to 1 step up over stock bore.,new spark plug, new air filter,new connecting rod, and did carb cleaning, also I add semi synth 2T oil (30% ) . Also guide me to stop leaking oil pump. Does reed valve play any role in pick up of bike? pls.
I think there are others that could be of better assistance of you, since I don't have experience with the geared 2T bikes. Any 2T could possibly benefit from port work and getting the compression and squish right. That's takes time to do a lot of measurements and you must know what you're getting into and realize the risk of ruining things. Two-Stroke Performance Tuning by A. G. Bell is a good book to get you going with the knowledge to handle that stuff. Oil pumps also aren't my thing. I stop all of mine by removing them and pre-mixing my gas/oil. Sometimes it's as simple as a loose fastener, bad check valve, or a damaged hose though. First thing is to be certain of where the leak originates, which may require some cleanup. Reeds do make a difference, though just swapping to CF or fiberglass reeds on my scooters has never been a drastic change. Probably the most difference I've felt from a reed change was moving to a block like the VFORCE-3.
@@49ccscoot Thanks for the reply Sir... The engine does run but have yet to find a manual. its a 2007 TGB Sunset 50cc with a Mikuni carb. Also seems to dump a lot of oil right from the carb when its on the side stand. Any ideas ?
@@Michael87r Not normal. If it is pre-mixed (you have to add oil to the gas tank) then the float height is probably too high. If it is oil injected (has a reservoir for 2T oil) then you probably have a malfunction somewhere in the oil delivery system. Some use a little ball valve/check valve to keep oil from flowing when the engine is off. That may have failed.
@@49ccscoot It is oil Injected, pulled the oil delivery/oil pump off and cleaned it. Seems to be functional. Still seems to do it though, maybe a new pump is in order. I'll update you as things progress. And thanks again for all your assistance.
very good job, nice video. I need some help if you can please. my scooter, a Honda 250cc when engine is cool can't stay on except if i give some gas. when the engine is hot enough, runs normally. please can you tell me what the problem might be? thanks .
I'm not real familiar with the 250s, but that sounds like the symptoms of a bad enrichment or choke system. If it has an automatic enricher, that would be the first thing I'd check out.
Great video, but if I have a manual choke (enricher) do I still need to get the engine warm? I do it anyway but I was wondering it 5 minutes at idle was enought? Also were do you set the idle screw when you first start to adjust the air screw? Thanks.
Still warm it up for a few minutes. 5 minutes of idle should be fine. Idle speed screw gets set wherever the idle speed is right. Idle mix screw is usually something like 1-2 turns out for a default guess.
It would depend on the characteristics of each carb exactly, but turning the idle speed screw in does the same thing that twisting the throttle open does.
So the idle speed adjustment adjusts idle speed. But also the air/fuel adjustment affects speed also Where do you start with the idle speed adjustment then?
very useful video, my scooter runs with the idle screw, screwed almost fully, I mean it idles with it screwed out about 1,1/4 factory spec but I can only do about 10km/h, with it screwed in almost fully I can do sometimes 30km/h but the engine has been rebuilt so I'm not sure about this, if it should be ok for the setting to work this way while I break in the engine or I should be able to run quicker. With this setting though I get very bad mileage, 7 liters of gas runs out in about 100km
@@49ccscoot Since I have cleaned the carb with wd40 and later with a spray for carb cleaning and also moved the needle higher and I must say that now after I start up the engine and let it run for a minute or two, the first minute of riding gets me up to 45/50 km/h but then max 30.. also from half throttle to wot nothing happens. From what I've learned so far it must be the main jet since raising the needle only helped so much. Also I have the feeling that the automatic enricher is not working anymore since the cold start means kicking several times with very short periods of running. Very helpful material, I have learned a lot and I hope that in the end I will be able to tune the carb and have the scoot realiable
@90GTVert I'm a bit confused as right after cold start the engine revs happily and I can achieve a decent speed but in about 1 min the throttle does not react past half throttle. I opened the carb and seems the float is not level as you suggest so I concluded it might be the automatic enricher that gives more gas therefore better performance when cold than the running is too lean also I am missing the gasket from the accelerator cable mounting on the carb so I might get a rebuild kit, very very useful tutorials!
@@ruyutransport2298 The engine requires more fuel when cold, so it could be that it's rich and once warm it's just too much fuel. Could also be that the cold start enrichment is delivering a lot of fuel and it doesn't like it after without the fuel. I would do some test passes WOT once warm with different main jets and record results as detailed in the link that I provided.
Thanks for your explanation.My bike Yamaha FZR 250. i cleaned my mikuni carburator (4) and cleaned main jet,pilot jet and adjust air mixture 2.5 turns out from the closing point.Cleaned the air filter.My problem is 3 times failed my eco (smoke) test and result show more petrol consumption.but last years easily pass the eco test.My problem is need to reduce petrol.How can i adjust/reduce petrol flow ?please help.Thanks.
That's an old video, but still very usefull! I have one question... If I have the mixture screw unscrewed more than half a turn, my engine is idling very high for 10 to 20 seconds and then falls down to a "normal" idle revs. I have to have this screw out no more than half a turn in order for the engine rpm to instantly fall back to idle after I release the throttle. Does anyone know what could be the culprit? I thought that engine must be leaking somewhere but it sealed the exhaust and intake and filled it with 1.5bar of pressure and it holds it weill, so no leak. I also have to mention that I had to put a 1mm washer between the carburetor and an idle enricher in order to be able to start the engine. If this washer wasn't there you have manually crank it for three minutes to start it. I have a minarelli horizontal two stroke 50cc engine (CPI/keeway).
Lean running engines will often experience high idle that drops after some amount of time. Usually it's worse if the engine is hot. It will happen when the needle is too lean as well, so you could try moving the clip down a groove on the needle and see how it changes.
I've got an old PW50 and it idles perfect when cool but once it's warmed up it idles high enough to move the bike. You figure adjusting these screws will take care of that issue?
Not expecting an answer but which hose goes to which lead on the carb? I know… Should have taken a picture. 2 fuel hoses go on top when mounted. One has some sheilding and a coil 2003 Moskito SX 50cc
Most don't have 2 fuel hoses. Fuel would most likely be the protected hose and should be from the petcock/fuel tank. Generally it's the largest fitting, facing up or out on the side. Vacuum for the vacuum operated fuel petcocks is generally a smaller hose that goes on the center nipple that faces up. Side nipple that's small should be oil injection.
@@49ccscoot Yeah oil injection is on side just above idle adjustment screw. There are two ports on top. Then there are two hoses. One is grey and goes up under tank. It spits out fuel when you crank it. The otherhas some spring covering it. it too runs up to the tank. The tank has a barrel on bottom w 2 spouts. bottom spout is grey and naked. side spout has the spring/coil wrapped around it. The naked one is 1/2 the diameter of the spring one Just looking to find out which hose goes where on the carb. Again it has two spouts on top.
You know what I think I answered my own ?? It looks like the spout on the “out” connection going to the engine is smaller than the one by the from (air intake)
@@gulgul2006 Trace the hoses to see where they go on the petcock. 49ccscoot.proboards.com/thread/3653/vacuum-petcock-fuel-valve-connections Fuel hose for carb will lead to the float needle and seat in the bowl. It's going to be the largest nipple on the carb in most cases. Vacuum connections on a carb will lead to the intake tract so they have a vacuum source.
Thks four your video I have a Peugeot V-Clic 50cc 4T when I started the scooter the item going up for few seconds and caming down after 5 seconds is up again constantly up and down can you please help me thank you very much apreciate
Nice video. I have a small question though. Lets say I just came from a ride in a cold night and my engine had a lot of heat. I park my bike in bike in the garage where the air is still so heat waves rises directly underneath the fuel tank. My fuel cap has a vent hole but no vent hose. The next cold morning I try starting my bike but there was no sign of life. I checked the spark and that was fine, I cleaned the carb recently and it was working fine with all the adjustments from before. I used choke and I didn't flood the engine. I was wondering, could this be an issue caused by too much venting of the heated fuel?
+Nitrow Boxhead bounty If you think it's venting related, take the gas cap off and try. If that doesn't solve it, it shouldn't have anything to do with venting. If you mean evaporation, unless you had only a thin layer of gas in the bottom of the tank, it shouldn't be an issue. I'd look more to usual suspects. Is there fuel making it's way to the engine and is there good compression.
This is one of the better guides for adjusting tje carb, thanks for that! Still have some questions tho.. how many turns out on the idle screw is a good way to start when starting from scratch? Also, is that all made without the choke pulled in right? Usually if i start cold i need the choke in to even be able to start.
Don't tune with the choke. Let it warm up, then tune. For the baseline guess on a new carb, try watching the slide and turn till you can see that it has opened just a tiny bit. Better to have it too low and die out than too high and take off.
Got it screwed all the way in.to idle properly on the mixture screw.....you think pilot jet still partially plugged? Will idle nice when warm..was sitting for years .. maybe I didn't clean pilot jet enough..a little difficult to start cold..
Same carb 50cc 2 stroke eton viper Japanese bike... carb just floods the cylinder... float/needle is working... tested it by turning on the gas with the bowl removed and seen it stop flowing when lifted the bowl... is that little rubber nipple required for the other side since it's just a hole right into the intake?
Check little stuff first. Kill switch set to run, still has fuel, alarm not on... Sounds silly, but it's surprisingly common for someone to use the kill switch and the next person that normally only uses the key can't start it. Checking for spark is quick and you can often feel if compression is low by working the kick starter. Sometimes it's not the thing last touched. If he just messed with the idle settings, I'd start by setting the mix screw 1-2 turns out from seated and see if that's much of a change or allows it to start. If he did more, find out what he changed.
Are you forgoing potential improvements in performance by choosing an airbox over an open filter? By the way, once I get my PayPal account funded after the holidays, I'm going to join your site, even though I'm a 150cc guy. That way, I'll be able to contribute a little something in appreciation of these vids. I encourage those who feel they have gained valuable knowledge from them to do the same. I'm a broke English teacher in Mexico, but this knowledge has served me well.
Right on. Thank you! Kymco has this one so restricted, there is no control over air/fuel mix (other than the idle mix) and the needle can't be adjusted.
Hey man great video, so do you adjust the screws while the engine is still running? OR do you adjust te screws while the engine is off, then start it, then turn it off to adjust, then start it etc.?
Hey thanks for posting this video it's really helpful. I was wondering what's wrong with my carb. It only runs on choke, once I take it off choke the engine picks up revs and then dies. Which screw should I adjust? Is this a lean or rich mixture? From watching your video i did not understand what to do with the idle speed screw. So do I just adjust the idle mixture screw and leave it at that? Or do I go on to adjust the idle speed screw after? Iv been trying to adjust the carb for a few hours and still can't get it to run without choke. Any advice is appreciated.
The enricher adds fuel to richen the mixture. If it is indeed a choke on yours it cuts off air, which also richens the mixture. So the fact that it runs with the choke/enricher engaged and not without should tell you that you need to adjust the idle mixture screw toward rich. The idle speed screw is just used to set how fast the engine idles and you just need to keep adjusting it if necessary to keep the engine running at a steady speed so it's not cutting out or trying to take off. There's also a possibility that you have a clogged pilot jet or it could be an intake/case leak.
Hi. I've got a 55 plate gilera runner sp50 and it runs fine on idle and low speeds. But it bogs down on full throttle. Any ideas? I know it's running too rich from the spark plug but not sure how to sort it. Thanks
+Cody Sparrow When the problem is at full throttle, you should be looking at the main jet. It's either the wrong size for your application or it's clogged. There's a chance that float height is off and making it rich, but usually the low throttle operation is affected more.
Hi, thanks for getting back to me. I've noticed that when the engine is running cold its not affected but gets worse the warmer the engine runs. Could that be caused by the same thing? Thanks
Can someone tell me what the upper left copper nipple is and what it does. I’ve got this hyosung sd50 rush challenger 2002 that had a cable shoe fitted with a white/red cable connected to it between that. And onto where it looks like a vacuum hose would be put there was another cable shoe mounted straight onto the nipple with a yellow/white cable connected.. need to know what this is since i havent seen this before. It will sometimes start and sometimes wont start. Will idle for 10 secs and then die out. Havent seen this on ang other carb.. New to these korean 50cc’s
i bought a couple of 49CC 2 stroke scooters, and mostly drive them up at 6K in elevation. so if im hearing this video correctly, i should be screwing the idle bolt in, to increase the air flow?
You'd probably want more air to lean it out a bit. If the idle mix screw is on the air filter side, then it's controlling air. Screwing it out allows more air in. If it's on the engine side, it controls fuel. Screwing it in reduces fuel.
dose having the lowest mixture adjustment and a good idle adjustment effects the engine? btw my scooter runs smooth with this adjustment it doesn't stop i have a 2t 49cc bw's booster 5 2003
Hi tks again four your vides, I fit on my scooter two stroke a new 50cc cylinder and piston the scooter wheen I start and give a gas is not go and same times is cut off also black smoke came off from exhaust, I remove the spark plug and is oil on it what you recommend to do please? Tks
If it's definitely oil fouled you've got too much premix (32:1-40:1 is good for most oils) or the injection system is messed up. If it's gas and oil rich it could be too large of a jet, bad reeds or reeds not sealing, or some type of air restriction.
Is there ONE VIDEO ON ALL OF UA-cam WHERE THEY TAKE A 50cc 2 Stroke Carb and start from attaching it to manifold and showing each tube and where they go?
Dude you need a medal for how consise and accurate your information is here! Perfectly broken down so that even laymen could grasp the workings well done sir
I agree. I was having so many problems and getting excess information on other channels. This broke it down barney style!
Good job you came right to the point . Some guys talk to much about things that has nothing to do with the subject. Good job, very helpful.
Thank you.
Able Reyes jthe
Finaly a simple video that gets strait to the point and is broad enough to give a general but great understanding I thank u for this
Hello
My name is Jani Soini and I'm from Finland and I removed the restriction from my exhaust pipe. Now I have to change the main jet to a bigger one but don't know what sice... My friend's say that if I don't change it to a bigger one the motor might be ruined. Can you please please help me!?? 😯 I have a sym Jet euro x 50cc scooter. Can you tell me what size pilot jet is good for my bike ? I would be forever grateful if??
Bonjour mon j ai un petit prommble avec mon carburateur quand mes le pleins je fait une journée avec le scooter c est un imf
@@jamppa80 11111¹
🤣😂😭🤔😂facts
After 8 years,and right on time when i needed this,great work and thank you
Haha! Me too. I'm guessing it's 2-1/2 turns as mine was never adjusted properly..
It's difficult to adjust these to that "Sweet spot" when you can't get the engine starting to begin with
Best way I’ve found to help with this, set the tuning back to factory tuning(usally 3 full turns out for both air and gas screws) then give it a quarter turn back in on the gasand it should be enough to start the bike until you can actually tune it. It’s just 50cc that are an ass because of how exact you have to be sometimes
By far the best and easiest well said of this type of carburetor adjustment on UA-cam.
Man, this is the best video I’ve seen on how to set the idle speed, you have saved my life. I’ve been trying for weeks to find someone to teach me and no one really knows how to properly do what you have just explained, not even the so-called experts. Thanks to your video now I know how to do it, I can’t wait to go tomorrow and set my DD2 rotax carburetor and FINALLY be able to drive like it’s supposed to. One again, THANK YOU SO MUCH 🙏👍👍👍
great video and breakdown. my kids little atv was idling rough, thumping...and backfiring every so often. Adjusted the idle and richened it up a little bit, idling like new, smooth, and no backfires. Thank you!
My goodness so simple you have explained something so simple to do. Well done mate.....Andrew of South Africa.
this is exaclty what i've been waiting for, this is EXACTLY I don't mean to sound like Katt Williams but this is exactly what I've been waiting for
Thank YOU!!!!...not TOO technical; straight forward. I've owned 70's thru 90's motorcycles(n cars) but these tiny carbs are SO sensitive--the lazy part of me wanted to just buy a NEW carb online without manual choke...but THIS video gave confidence that all these giant BOOK manuals have given me (tiny print; way too general, etc..)
im working on an '85 Honda Aero 80cc thats been in an attic since 1987 with a full tank of gas. These past few days have been a nightmare! Turns out, they havent made gas tanks for this scoot since '87, and this is too far beyond repair. Ive worked on tons of Chinese scoots using your help. Now, I can thank you for helping with this one. The air restrictor was stuck wide open due to some gunk build up even after ive cleaned and rejetted. i finally just looked throught the dang thing after this video and saw it stuck wide open. Its too late to try and get it running tonight with the kids being asleep, and I have to work all day tomorrow. Now its going to be on my mind all day! Thanks AGAIN!
Good luck with it. Hope that does it for you.
Thank you for this simple video without any bullshit, nicely straight to the point
Thanks so much man, this is what I needed to know. Not many carb videos cover both both screws.
Minus both
Finally a video for novices, thank you!!!!
Because of you my Yamaha CA50 runs again . Thank you for a very easy vid that most of us can understand.
Glad to hear it!
This is great, similar principles to italian scooters i.e. derbi model with piaggio motors. My Scooter was running way too rich as indicated by the soiled spark plug. The scooter recently developed a significant vibration at about 1/4-1/2 throttle and at idle. After turning the idle mixture screw out about 8 full turns, the scooter idles much more smoothly, doesn't lag on take off and doesn't vibrate anymore. It actually has never ran this smooth. Great explanation of the process and how the carb works! Thank you. 2007 Derbi Atlantis Bullet 49 cc with piaggio engine.
Be careful. If turned out too far the screw gets loose and can loosen further with vibrations and end up falling out. Replace the idle/pilot jet if necessary to make sure the screw can be adjusted without it being too loose.
Thanks for breaking this down barney style! Helps 100%
I just got a 450$ Chinese scooter and man the carb is giving me a real hard time I ordered a new one after trying to clean the old one several times but your videos have helped so so much thank you
Glad they helped!
Great video. Simplifying the dark art of understanding a carb. Much thanks.
Very helpful thank you!!
Where on this carburetor is the fuel inlate, at the front or at the top?
It's the big barb at the top. Watch near the end of this : ua-cam.com/video/UipC6DLD-EE/v-deo.htmlsi=PuMtbGcDENr_K4FJ
Yes!! Finally... A simple explanation. Thanks!
I’ve been looking a video like this for months!!!! Perfect
THANK YYYYYOOOOOUUUUU!!!!!!!!!!!!!!!!!!
I been looking alllll day to c what this 2 screws do to my mini bike jeez. Finally to the point. Great no no no awesome vid bro thanks for the info I DEEPLY APPRECIATE IT
P.S. I gave u a 👍🏻 u more than deserve it
Can’t even explain I’ve been trying to find this video for forever exactly what I needed you helped a lot ❤️
Thank you! I've been having a carb issue(keihin pb16/kymco like 50 2t) & took it apart for the first time today. At a point when changing the main jet (w/out fully removing the carb from the engine) I 'adjusted' the float w/out realizing. I put the carb back together properly, but the engine isn't firing (w/good spark and compression). A suggestion has been made to alter the idle mix since my plug is wet. My carb is different than this one, but it is very helpful to get a visual & explanation.
all your video are so clear and easy to understand again pls continue to make more video thanks
Thank you. I will keep going.
this is the best guy for these videos.
I've looked up how to adjust mixture screw 300 times in the last week no one said anything about trying to get it to idle as high as you can with the mixture screws no wonder why I can't get my sled mixture screws right now tomorrow I can go out there and turn them one and a half out and then start turning them until I can get my highest idle and then back off my idle screws until I'm at my preferred RPM idle thank you !!!!!!!!!!!!!!!!!!
Hope it works out better for you this time!
I need a float for this exact carburetor, mine is off a Bombardier DS90 2stroke but they discontinued the parts.
Where can I find aftermarket parts???
Or can you give me a part number for this?
Take a look at PartsForScooters part number 161-214. There used to be some rebuild kits around if you searched for something like "polaris 90 carburetor rebuild". You can look in a Polaris parts manual for an outlaw/sportsman/predator 50-90 and see if they have a part you can get.
90GTVert you nailed it with the Polaris 90 recommendation!
Found a part number through the Polaris Predator 90 diagram!
www.partzilla.com/catalog/polaris/atv/2004/predator-90-a04ka09ca/carburetor-cb
Thanks again, very helpful!
Awesome. Glad to help!
Best video on UA-cam
You dont know how mutch you helped me. Thanks!
This helped me a lot with my honda City express from 1989. Thanks :)
This has made a lot of sense because soon as the vacuum pipe is on it doesn’t start use a vacuum pump tester it works I’m guessing ether the carb or vacuum tap isn’t working properly
Finally a video on adjusting screws. What is usually stock on a carb just roughly as I’ve rebuilt my carb which was all blocked up with the wrong adjustments?
1.5-2 turns out is usually a decent starting point for the mix screw. For the idle speed, you can make sure it's raising the slide a little and then you'll figure that one out quick enough when it's running.
90GTVert 1.5 to 2 turns out from all the way in or flush with the sleeve?
@@Jack-ns5zc Any time "turns out" is stated, it should be from seated (all the way screwed in).
Ah right, cheers
I"m in the middle of cleaning up my cousin kids atv's.. It missing hose's and out of adjustment . This video explains a lot. But one thing i am not sure of it what that Barb fitting above the idle screen used for?
Oil injection.
thank You!
How far should the Idle screw be open, given that its a first start after the carb was off for cleaning? What causes the engine to die out when I touch the throttle? Sorry if it sounds like a silly question, but I'm still at the "start it up, let it warm up, take it for a spin" part.
About 2 turns for a starting point on the mix. Look at the slide in the carb and turn the idle speed screw till it's just barely open. May have to work the throttle a bit to get it started and turn it in more, but that's better than having it take off when you start it. You may have the wrong mix settings or needle setting or perhaps something is still clogged in there. Air box should be installed if not already.
***** hey I have a 2 stroke I just bought and and I replaced the air filter and noticed some oil in the card laying in a crevice by where the air filter connects. Also it smokes quite a bit even after it starts and runs for a bit. Stock muffler restricts the power a ton and runs perfect with it just slow when I put the performance muffler on it runs spectacular but after three minutes when giving it gas it feels like it's missing and won't pick up and go then out of nowhere takes off like a a bat out of hell again and then eventually bogs out and stalls.
You probably need to tune the carb for the aftermarket pipe with a larger main jet.
Could be just low quality oil making it smoke, unless it's a new problem with a scoot you've had for a while.
Muito obrigado pela super dica,eu tenho uma yamaha Jog 50cc e demorei muito pra encontrar o ponto certo da regulagem do Ar e da marcha lenta,agora deu certo 😘👍🏼👌🏼 Tank You Man 😎👍🏼
Hi this was very helpful I just brought a aeon mini kolt with a oil injection all pipes missing and not sure where to connect the oil was wondering if you could give me some advice thanks
In this video, the oil injection port is the one above the idle speed screw. You'll often see that it's a barb with a large base, because many (not all) house a check valve with a ball and spring in there.
Hope I get reply so once I go over 2& half turn I get the best idile any more there’s no change so do I stopwhere the best idile is....
Are trying to say that you should be able to screw out for the best idile and before the screw pops out you should get a drop in revs as well ?????
I would try a larger or smaller pilot to see what happens. Depending if you have an air or fuel screw.
My revs at idile on mixer screw is two and half turns out the revs increase at at 1/half between one and half and two and half these no difference so where do I leave it
Very good video straight to the point no messing about thank you!
What if turning the air screw all the way in or all the way out makes no difference at all? I bought a new carburetor which is sold for my bike model and it is supposed to work out of the box. And indeed it works, idle, half throttle and full throttle. But I cant set the air screw cause it looks like it does nothing.
Maybe the float height is wrong or the pilot jet is way off.
@@49ccscoot using it today I found out that it works pretty rich. Because when I turn it on and rev it, lot of smoke is coming out of the exhaust. Also I have to give it throttle in order to turn on. It does not turn on by pushing only the starter button.
The carb is a brand new 17mm chinese gurtner clone. Replaced a dellorto phva 12.
@@cabrinhaGR So much for "supposed to work out of the box". Possibly too large of a main jet and pilot jet.I'd prob start with main jet swaps to see if that helps it all around.
@@49ccscoot main jet comes into play when throttle is fully open, right? And when I am on wot everything is ok. In fact everything looks ok in the whole spectrum, from idle to wot. The only problem is that the air screw does not affect mixture (no rise or fall of rpm, no engine stall etc.).
@@cabrinhaGR It does. Large main jet could make everything bad, but if it's good everywhere else then prob don't start there. New or not, I'd clean the carb. I don't trust Chinese stuff to be setup properly or free of debris.
I lost the pilot screw when riding a Honda Spree years ago. Somehow it kept going and got me home. Same for when one of the carb bolts fell out and I had to zip tie the carb on to get me home.
+Guajiro Konn You've pressurized the cases (about 6psi) and made sure pressure does not escape? Checking with propane, water, carb cleaner etc... for intake leaks is not always effective on a 2T. Reeds in good shape? Float height set properly?
hey I just picked up a eton beamer 2t and it idles too high even with the idle speed screw at its lowest setting, would i have to adjust the mixture setting? or is it a different problem?
Make sure the cable isn't pulling the throttle open. There should be adjusters. One at the handlebar and one at the carb. If there isn't a small amount of slack it'll hold the throttle open. Could be that you need to adjust in more fuel or have an air leak as well.
thanks for the info will take a look at her tomorrow.
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KISS, you are the champ Thank you
Yup thank you officially I just adjusted both my screws and it’s running perfectly thanks bro really appreciate it wish I could give u more 👍🏻because I would
To adjust my bike, do I have to adjust first the idle speed, and then the mixture screw??
Then if the engine goes to fast I will have to turn again the idle speed? and then the mixture again?? or when the mixture is done good it doesn't have to be touched again?? thank you so much
Would u mind explaining the rolling wrench pwk 21mm carb that's said to be for the bbk qmb39. Has a blue an red knob . Blue on left side an red on right side an both are on the air filter end of carb
No exp. Just looked at pics. Blue is idle speed. Guessing the knob will be choke. Idle mix screw should control air on the PWK. Looks like a $25 AliExpress carb to me, with extra decals.
Great Info!! thanks a lot!! what about if you get it good, but on WOT from standing point she bogs and spits??
I had it ok but the engine was flooding. I took out the carb and cleaned it, and this tarted after i installed it back in. Just cant get it right this time. Any tips on what might be the problem?
The tune may be different now with it cleaned. Make sure the float height is good and see if needle settings get you better response.
@@49ccscoot thanks a lot buddy found the issue, float was slightly bent and starving the carb : ) running great again!
Excellent tutorial will try this on my 350 LC it’s bogging at low revs up to 3000 rpm then it’s off like a scolded cat nice work mate
Give it a try since it can be quick and simple if the carb is easy to access. If it's RPM dependent and not throttle position dependent though, you may have something else going on... like a clutch issue for example.
THANKS.. BIG HELP AND EASY TO UNDERSTAND... 5 STARS....
Do you know what set of jets this carb would take? I have a 50cc Rivera Jog and the carb looks exactly like this one. Thanks in advance! This was an awesome video!
They're Mikuni VM11/22 jets or I've used Dellorto 6mm jets in them before. Whatever you use, get a set of all one brand and type. Don't mix and match or sometimes the sizes aren't accurate to each other. Name brand preferred... Mikunu, Polini, Stage6, and so on.
Let me understand this: The fuel-air mixture adjustment screw is the one which is spring loaded, while the idle screw is not?
There's usually a spring under the mixture screw, but it's not generally visible without taking it out. The idle screw often has a spring under it that can be seen without any disassembly.
@@49ccscoot
That clears it up (thank you), because everywhere else I looked, it is the idle screw
only which is shown having a spring.
That was awesome and to the point. Should I start with a new plug or a clean the plug? Or does it matter ?
If your just starting out, as long as it's not fouling you're OK. If you get to fine tuning, especially higher throttle settings, then maybe put a new plug in.
@@49ccscoot wow thank you man for responding so quickly. It's not fouling the plug, just kind of gutless. The other Eton viper is much snappier. Both are Eton Viper 90s. Getting ready to sell them. Kids out grew them and want someone to enjoy like we did. Thx again.
hi, thanks for the video. I am busy rebuilding a DINLI JP 502 and bought the exact carb, but are not sure about the hose connections? I only have the fuel hose and a thin hose coming out of the engine. There is however 4 hose connection points on this carb. I understand some is vacuum and should be kept open, just not sure which is which. Have you got a diagram of it. All the manuals of Dinli JP 502 I found on the internet is "shadowed" and I can not make out anything on it. I normally fix mowers and whipper snippers. This is my first quad job...
Connections shown here :
ua-cam.com/video/UipC6DLD-EE/v-deo.htmlm45s
I know some older Yamahas didn't have mix screws, but I don't know the reason.
I cleaned the carb and its clean as hell now should i make the idle mixture richer
the belt looked fine. idk what you mean by "If it gets narrow it won't ride as high in the variator for best speed" ?
Adjust mixture until there is no lag or hesitation when I goose the throttle a little? How can I make sure it's not too lean or rich, as I've got it idling pretty good, now. Thank you for your time, Bro'.
If it responds well, idles smooth, and doesn't hang when you let off or die out; it should be alright.
Thanks.
These tips should help me with a OKO 21 mm. carb. larger the numbers on a pilot jet correct?
The main jet should be the larger number. Not sure if that's what you were asking. If not, please clarify.
Hello
Thank u for ur efforts to explain such a complex topic so practically.
can u pls guide me on how to get the max pick up on my Yamaha, 2 Stroke RX100 92 model?
I have put new clutch plates, new piston, rebored the block to 1 step up over stock bore.,new spark plug, new air filter,new connecting rod, and did carb cleaning, also I add semi synth 2T oil (30% ) .
Also guide me to stop leaking oil pump.
Does reed valve play any role in pick up of bike?
pls.
I think there are others that could be of better assistance of you, since I don't have experience with the geared 2T bikes. Any 2T could possibly benefit from port work and getting the compression and squish right. That's takes time to do a lot of measurements and you must know what you're getting into and realize the risk of ruining things. Two-Stroke Performance Tuning by A. G. Bell is a good book to get you going with the knowledge to handle that stuff.
Oil pumps also aren't my thing. I stop all of mine by removing them and pre-mixing my gas/oil. Sometimes it's as simple as a loose fastener, bad check valve, or a damaged hose though. First thing is to be certain of where the leak originates, which may require some cleanup.
Reeds do make a difference, though just swapping to CF or fiberglass reeds on my scooters has never been a drastic change. Probably the most difference I've felt from a reed change was moving to a block like the VFORCE-3.
No hesitation when revved during idle=not too lean? Any help is much appreciated.
Where do you set the Idle Speed Screw prior to adjusting the Air Fuel Mixture ?
If it's on a running engine, adjust the speed screw until the idle RPM is roughly 2,000RPM or whatever your service manual says.
@@49ccscoot Thanks for the reply Sir... The engine does run but have yet to find a manual. its a 2007 TGB Sunset 50cc with a Mikuni carb. Also seems to dump a lot of oil right from the carb when its on the side stand. Any ideas ?
guess I should have mentioned, its leaking oil from the carb when its off and on the side stand. Is this normal ?
@@Michael87r Not normal. If it is pre-mixed (you have to add oil to the gas tank) then the float height is probably too high. If it is oil injected (has a reservoir for 2T oil) then you probably have a malfunction somewhere in the oil delivery system. Some use a little ball valve/check valve to keep oil from flowing when the engine is off. That may have failed.
@@49ccscoot It is oil Injected, pulled the oil delivery/oil pump off and cleaned it. Seems to be functional. Still seems to do it though, maybe a new pump is in order. I'll update you as things progress. And thanks again for all your assistance.
You a legend dude, thank you!
Is there a good rule of thumb regarding initial idle air-fuel screw adjustment (number of turns) before starting the engine?
1.5-2 turns out is where many like to start.
Thank you. My little lads quad bike idles beautifully now.
very good job, nice video. I need some help if you can please. my scooter, a Honda 250cc when engine is cool can't stay on except if i give some gas. when the engine is hot enough, runs normally. please can you tell me what the problem might be? thanks .
I'm not real familiar with the 250s, but that sounds like the symptoms of a bad enrichment or choke system. If it has an automatic enricher, that would be the first thing I'd check out.
thanks a lot. Yes it is an automatic choke. Is it any possibility off bad mix from carb?
You could try adjusting the idle mixture and idle speed to see if that gets you anywhere.
Just the right info i needed..
Great video, but if I have a manual choke (enricher) do I still need to get the engine warm? I do it anyway but I was wondering it 5 minutes at idle was enought?
Also were do you set the idle screw when you first start to adjust the air screw? Thanks.
Still warm it up for a few minutes. 5 minutes of idle should be fine. Idle speed screw gets set wherever the idle speed is right. Idle mix screw is usually something like 1-2 turns out for a default guess.
Hey cool video ! So at idle if you turn the idle speed screw there will be fuel sucked out of the main jet ? Because you raised the needle?
It would depend on the characteristics of each carb exactly, but turning the idle speed screw in does the same thing that twisting the throttle open does.
So the idle speed adjustment adjusts idle speed.
But also the air/fuel adjustment affects speed also
Where do you start with the idle speed adjustment then?
Start with the speed screw. Then adjust mix. If idle raises too much, correct with the speed screw.
very useful video, my scooter runs with the idle screw, screwed almost fully, I mean it idles with it screwed out about 1,1/4 factory spec but I can only do about 10km/h, with it screwed in almost fully I can do sometimes 30km/h but the engine has been rebuilt so I'm not sure about this, if it should be ok for the setting to work this way while I break in the engine or I should be able to run quicker. With this setting though I get very bad mileage, 7 liters of gas runs out in about 100km
Have you tried anything else, like main jets or needle settings. Idle mixture shouldn't be the main contributor to top speed.
@@49ccscoot Since I have cleaned the carb with wd40 and later with a spray for carb cleaning and also moved the needle higher and I must say that now after I start up the engine and let it run for a minute or two, the first minute of riding gets me up to 45/50 km/h but then max 30.. also from half throttle to wot nothing happens. From what I've learned so far it must be the main jet since raising the needle only helped so much. Also I have the feeling that the automatic enricher is not working anymore since the cold start means kicking several times with very short periods of running. Very helpful material, I have learned a lot and I hope that in the end I will be able to tune the carb and have the scoot realiable
@@ruyutransport2298 I've got much more detailed info about the carb tuning process here : www.49ccscoot.com/faq/carbtune.html
@90GTVert I'm a bit confused as right after cold start the engine revs happily and I can achieve a decent speed but in about 1 min the throttle does not react past half throttle. I opened the carb and seems the float is not level as you suggest so I concluded it might be the automatic enricher that gives more gas therefore better performance when cold than the running is too lean also I am missing the gasket from the accelerator cable mounting on the carb so I might get a rebuild kit, very very useful tutorials!
@@ruyutransport2298 The engine requires more fuel when cold, so it could be that it's rich and once warm it's just too much fuel. Could also be that the cold start enrichment is delivering a lot of fuel and it doesn't like it after without the fuel. I would do some test passes WOT once warm with different main jets and record results as detailed in the link that I provided.
Thanks for your explanation.My bike Yamaha FZR 250. i cleaned my mikuni
carburator (4) and cleaned main jet,pilot jet and adjust air mixture 2.5
turns out from the closing point.Cleaned the air filter.My problem is 3 times failed my eco
(smoke) test and result show more petrol consumption.but last years
easily pass the eco test.My problem is need to reduce petrol.How can i
adjust/reduce petrol flow ?please help.Thanks.
That's an old video, but still very usefull! I have one question... If I have the mixture screw unscrewed more than half a turn, my engine is idling very high for 10 to 20 seconds and then falls down to a "normal" idle revs. I have to have this screw out no more than half a turn in order for the engine rpm to instantly fall back to idle after I release the throttle. Does anyone know what could be the culprit? I thought that engine must be leaking somewhere but it sealed the exhaust and intake and filled it with 1.5bar of pressure and it holds it weill, so no leak. I also have to mention that I had to put a 1mm washer between the carburetor and an idle enricher in order to be able to start the engine. If this washer wasn't there you have manually crank it for three minutes to start it. I have a minarelli horizontal two stroke 50cc engine (CPI/keeway).
Lean running engines will often experience high idle that drops after some amount of time. Usually it's worse if the engine is hot. It will happen when the needle is too lean as well, so you could try moving the clip down a groove on the needle and see how it changes.
I've got an old PW50 and it idles perfect when cool but once it's warmed up it idles high enough to move the bike. You figure adjusting these screws will take care of that issue?
@@hulldefilade4897 Adjust when warm and it may.
Not expecting an answer but which hose goes to which lead on the carb?
I know… Should have taken a picture.
2 fuel hoses go on top when mounted.
One has some sheilding and a coil
2003 Moskito SX 50cc
Most don't have 2 fuel hoses. Fuel would most likely be the protected hose and should be from the petcock/fuel tank. Generally it's the largest fitting, facing up or out on the side. Vacuum for the vacuum operated fuel petcocks is generally a smaller hose that goes on the center nipple that faces up. Side nipple that's small should be oil injection.
@@49ccscoot Yeah oil injection is on side just above idle adjustment screw. There are two ports on top. Then there are two hoses. One is grey and goes up under tank. It spits out fuel when you crank it.
The otherhas some spring covering it. it too runs up to the tank. The tank has a barrel on bottom w 2 spouts. bottom spout is grey and naked. side spout has the spring/coil wrapped around it. The naked one is 1/2 the diameter of the spring one
Just looking to find out which hose goes where on the carb. Again it has two spouts on top.
You know what I think I answered my own ?? It looks like the spout on the “out” connection going to the engine is smaller than the one by the from (air intake)
@@gulgul2006 Trace the hoses to see where they go on the petcock. 49ccscoot.proboards.com/thread/3653/vacuum-petcock-fuel-valve-connections
Fuel hose for carb will lead to the float needle and seat in the bowl. It's going to be the largest nipple on the carb in most cases.
Vacuum connections on a carb will lead to the intake tract so they have a vacuum source.
Thanks for the very best explanation of all screws. Thanks again
Thks four your video I have a Peugeot V-Clic 50cc 4T when I started the scooter the item going up for few seconds and caming down after 5 seconds is up again constantly up and down can you please help me thank you very much apreciate
Check for intake leaks first. Loose connections, cracked intake, bad gaskets...
Totally helpful while you were showing how it works inside the carburetor.
Yo bro u really helped me bro best explanation lov it now ik how to set me screws
Nice video. I have a small question though. Lets say I just came from a ride in a cold night and my engine had a lot of heat. I park my bike in bike in the garage where the air is still so heat waves rises directly underneath the fuel tank. My fuel cap has a vent hole but no vent hose. The next cold morning I try starting my bike but there was no sign of life. I checked the spark and that was fine, I cleaned the carb recently and it was working fine with all the adjustments from before. I used choke and I didn't flood the engine. I was wondering, could this be an issue caused by too much venting of the heated fuel?
+Nitrow Boxhead bounty If you think it's venting related, take the gas cap off and try. If that doesn't solve it, it shouldn't have anything to do with venting. If you mean evaporation, unless you had only a thin layer of gas in the bottom of the tank, it shouldn't be an issue. I'd look more to usual suspects. Is there fuel making it's way to the engine and is there good compression.
thank you a video where i actually learned something
I don't know if you will reply, but when I start my bike cold it trottles to almost max rpm and calms down when it warms up, what should I do?
Try adjusting the idle mix and speed. If that doesn't get you anywhere, see if the automatic enricher (if equipped) is working.
Thanks for the video, useful stuff
This is one of the better guides for adjusting tje carb, thanks for that! Still have some questions tho.. how many turns out on the idle screw is a good way to start when starting from scratch? Also, is that all made without the choke pulled in right? Usually if i start cold i need the choke in to even be able to start.
Don't tune with the choke. Let it warm up, then tune. For the baseline guess on a new carb, try watching the slide and turn till you can see that it has opened just a tiny bit. Better to have it too low and die out than too high and take off.
Got it screwed all the way in.to idle properly on the mixture screw.....you think pilot jet still partially plugged? Will idle nice when warm..was sitting for years .. maybe I didn't clean pilot jet enough..a little difficult to start cold..
Could be. If you happen to have access to an ultrasonic cleaner, that's a good step for a stubborn carb too.
Same carb 50cc 2 stroke eton viper Japanese bike... carb just floods the cylinder... float/needle is working... tested it by turning on the gas with the bowl removed and seen it stop flowing when lifted the bowl... is that little rubber nipple required for the other side since it's just a hole right into the intake?
You will have a vacuum/air leak without it capped. Float could still be sticking when in the bowl.
@@49ccscoot yup... just took it all back apart... float has a little gas in it... thank you for answering...
Hi great video but can you help me with my problem my friend adjusted my carb then the bike wont turn on anymore. What should i do??
Check little stuff first. Kill switch set to run, still has fuel, alarm not on... Sounds silly, but it's surprisingly common for someone to use the kill switch and the next person that normally only uses the key can't start it.
Checking for spark is quick and you can often feel if compression is low by working the kick starter. Sometimes it's not the thing last touched.
If he just messed with the idle settings, I'd start by setting the mix screw 1-2 turns out from seated and see if that's much of a change or allows it to start. If he did more, find out what he changed.
Are you forgoing potential improvements in performance by choosing an airbox over an open filter?
By the way, once I get my PayPal account funded after the holidays, I'm going to join your site, even though I'm a 150cc guy. That way, I'll be able to contribute a little something in appreciation of these vids. I encourage those who feel they have gained valuable knowledge from them to do the same. I'm a broke English teacher in Mexico, but this knowledge has served me well.
Right on. Thank you! Kymco has this one so restricted, there is no control over air/fuel mix (other than the idle mix) and the needle can't be adjusted.
Hey man great video, so do you adjust the screws while the engine is still running? OR do you adjust te screws while the engine is off, then start it, then turn it off to adjust, then start it etc.?
Thanks. Adjust while running and you can listen or watch a tach for changes.
90GTVert thanks!!👍🏻👍🏻
Best explanation ever👍👍👏
Hey thanks for posting this video it's really helpful. I was wondering what's wrong with my carb. It only runs on choke, once I take it off choke the engine picks up revs and then dies. Which screw should I adjust? Is this a lean or rich mixture? From watching your video i did not understand what to do with the idle speed screw. So do I just adjust the idle mixture screw and leave it at that? Or do I go on to adjust the idle speed screw after? Iv been trying to adjust the carb for a few hours and still can't get it to run without choke. Any advice is appreciated.
The enricher adds fuel to richen the mixture. If it is indeed a choke on yours it cuts off air, which also richens the mixture. So the fact that it runs with the choke/enricher engaged and not without should tell you that you need to adjust the idle mixture screw toward rich. The idle speed screw is just used to set how fast the engine idles and you just need to keep adjusting it if necessary to keep the engine running at a steady speed so it's not cutting out or trying to take off. There's also a possibility that you have a clogged pilot jet or it could be an intake/case leak.
Hi. I've got a 55 plate gilera runner sp50 and it runs fine on idle and low speeds. But it bogs down on full throttle. Any ideas? I know it's running too rich from the spark plug but not sure how to sort it. Thanks
+Cody Sparrow When the problem is at full throttle, you should be looking at the main jet. It's either the wrong size for your application or it's clogged. There's a chance that float height is off and making it rich, but usually the low throttle operation is affected more.
Hi, thanks for getting back to me. I've noticed that when the engine is running cold its not affected but gets worse the warmer the engine runs. Could that be caused by the same thing? Thanks
The engine needs more fuel when cold, so as it warms up a rich condition may show worse symptoms.
Can someone tell me what the upper left copper nipple is and what it does. I’ve got this hyosung sd50 rush challenger 2002 that had a cable shoe fitted with a white/red cable connected to it between that. And onto where it looks like a vacuum hose would be put there was another cable shoe mounted straight onto the nipple with a yellow/white cable connected.. need to know what this is since i havent seen this before. It will sometimes start and sometimes wont start. Will idle for 10 secs and then die out. Havent seen this on ang other carb.. New to these korean 50cc’s
i bought a couple of 49CC 2 stroke scooters, and mostly drive them up at 6K in elevation. so if im hearing this video correctly, i should be screwing the idle bolt in, to increase the air flow?
You'd probably want more air to lean it out a bit. If the idle mix screw is on the air filter side, then it's controlling air. Screwing it out allows more air in. If it's on the engine side, it controls fuel. Screwing it in reduces fuel.
dose having the lowest mixture adjustment and a good idle adjustment effects the engine?
btw my scooter runs smooth with this adjustment it doesn't stop i have a 2t 49cc bw's booster 5 2003
Keeping it in tune at idle can help it run well at low throttle as well.
Hi tks again four your vides, I fit on my scooter two stroke a new 50cc cylinder and piston the scooter wheen I start and give a gas is not go and same times is cut off also black smoke came off from exhaust, I remove the spark plug and is oil on it what you recommend to do please? Tks
If it's definitely oil fouled you've got too much premix (32:1-40:1 is good for most oils) or the injection system is messed up. If it's gas and oil rich it could be too large of a jet, bad reeds or reeds not sealing, or some type of air restriction.
Can you do a video on tweaking needle jet ?
Is there ONE VIDEO ON ALL OF UA-cam WHERE THEY TAKE A 50cc 2 Stroke Carb and start from attaching it to manifold and showing each tube and where they go?