make sure you clean the carbs the way i did it, if you dont you will melt a piston, also if you have made changes in clutching then yes you will run in to all kinds of other issues when trying to tune the system. don't just clean one thing, you can't clean without soaking the carbs, you can't clean without blowing them out with compressed air too. when done you need to synch the carbs, and you need to set the air screws to factory specs - if not youll be walking home:)
you need to take it right apart and blow out the passages and clean it, change the pilot jet and needle/seat. Set it to factory specs and it will run fine.
Best explanation, that I've seen of Mikuni VM Carbs. Much needed, because they are prolific. Seems like they're in everything! Btw: Not a big deal, but you might have mentioned, about how the idle screw works...
if you havent changed anything then leave the jetting alone, you need to clean the carbs again and make sure you blow the passages out with compressed air. are the plugs dry from low throttle to 5000rpm or wet? if wet then its flooding, if dry then starving. I suspect a good cleaning will fix it up. Make sure those pilot jets are flowing properly and nothing stuck in there.
its kinda funny cuz i have a 1980 kawasaki drifter and i have the original shop manual for it to and in the manual it actually explains all of this in pretty good detail. but u did a really good job of explaining it so keep it up :)
They should slide in with little to no force. they have to be lined up correctly though. make sure you didnt nick the jet or damage the carb body - if so just clean up the ear and try again.
Really nice work. I've got some issues Im stumped on with my kids Suzuki 50 3 wheeler. its got the tiny Mikuni 2 stroke carb that has been picky since day one. Now, Ive got it where it will only run with the choke lever all the way closed. I've tried adjusting the 2 mini headless screws to no avail. Any help is appreciated.
The choke is used to let more gas in then air so the bike starts easier. I am pretty sure it is your main and pilot jets try going up by each size untill you feel that it is getting a good amount of gas and your spark plug has a nice coffee brown color. You will know when you have hit the right jets if your spark plug has a nice coffee brown color.
What about the air jet that feeds the main . It's Lines up with the main jet, the big hole on the air filter end. If you leave it out it will never run right.
Thanks for the vids, very informative. One question, I took the needle jets out for cleaning but I'm having a hard time to get them back in. I've tried from the top as you mentioned with the groove lined up. Do these things go in with some force or should they slide right in. Any help or tool recommendations would be helpful... thanks!
My bike will only rev up with the chokes on, it won’t rev with them off. It just goes blahhhhhhhttt and dies. The plugs have always been very sooty and black, which tells me it’s too rich. Since the Mikuni starter circuit is different from a standard choke, is it giving me more air to the mixture while it’s on and throttle opened? Which is why it can then rev with the choke on? With the throttle closed, it will barely idle with the starter circuit on. Been chasing down the tuning with these carbs for weeks. Air screw is almost falling out to achieve a rise in rpms; I have smaller pilot jets on the way. Any help would be greatly appreciated. Honda 400cc with Mikuni VM 32’s.
Trying to get a 95 Timberwolf 250 to idle. My brother cleaned the carb and rebuilt with an "all balls racing" rebuild kit. Still won't idle. You mentioned the pilot screw doesn't need to be adjusted that much.. We put a muffler on the quad because the old one was all rusted. Him and his friend were trying to get it to idle and I remember him having the pilot screw 2 turns out and he was trying 2 1/2 etc. I've been reading into it and the manual says 1 1/4 turn for the pilot screw. If it doesn't idle at 1 1/4 turns out what else could we try? Did some reading and going to check the float height and also drain the tank and put fresh gas. Other than that I have no idea what could cause it not to idle.
Lots of Mikuni's also use an Air Jet located inside of the intake venturi. I believe in your VM manual it is shown as item number 25. Can you explain how the Air Jet works in conjunction with the pilot jet and air mixture screw? Does changing the size of the air jet change the intake vacuum during starting allowing more or less fuel to enter?
I recently ordered a Mikuni VM16 Carburetor for 2 pit bikes and have been having issues with them. One of them came in and the bike would start, but it would only run on half or full choke even after being warmed up. Then, once warmed up, the bike would bog in the mid range and not be able to get to peak revs. Also, when I turned the choke off, and tried to rev to keep it going, it would create tons of smoke. On the second motor, it doesn't start at all. It just floods. Reset everything back to factory spec and let the engine sit and tried again and it flooded 5 times in a row in just 3 or 4 turn overs. Can I get some help with tuning these?
Great Video! I have dual carb snowmobile but it floods the plugs first pull. When I pull the plugs and pull start it sprays and i mean its like a fountain of gas comes out. What would you guess the problem would be? THANKYOU!!!!!
great stuff but the float valve does not meter anything! it just ensures the bowl remains full but does not flood. as you say, the jets meter the fuel.
Great video very informative! Ive got a vm26 on a 79 jd trailfire 440 ive cleaned the carb very well I usually spend 2 to 6 hrs on these "I have 3 trailfires n have worked on many others" originally the sled was flooding basically while just sitting there, replaced needle n seat fixed that issue. now ive got a low end bogg, 1/2 a turn to 2 n 1/2 out on the air screw 2 n 1/2 out book says max although it seems to improve a little that far out. What do you recommend?
Hi good vid. I have a kawasaki 440 with a single carb but i can only get it to run if i live the shoke close just a little bit do you happen to know what could be the problem ( i clean up the carb two times just in case but maybe im missing something or adjusting something thank you and hope to hear from you soon
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.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?please help.Thanks.
Thank you for your videos. I am repairing a snowmobile and noticed that on carb has a what looks like a ball bearing in a tube that leads to where the choke plunger goes in. One of the two carbs is missing that ball bearing is that something I can or needs to be replaced?
My -01 edge with flatslide carbs won't idle. Below 2500 rpm it just goes "boooow" and dies straight after. To lean mixture? The idle screw is at its bottom. I would appreciate your help :)
I have a 98 Summit x with the HAC deleted and oil pump deleted as well. the thing will idle but when I go anywhere near the throttle it bogs, won't rev and if I go to WOT it will die. its not the track (belt is off) and the fuel pump is working. I think it must be the carbs although the previous owner claims he just cleaned them last season...any ideas? I run 40:1 mix with 91 octane and ski doo oil
I have a problem with the choke not working, was hoping you would explain how it works, you only mentioned it once, guess it is not considered part of the carb.
It is like it is stuck, The dealer replaced the cable, and it worked for a while, but I have to prime it down the plug hole to get it started now and when it warms up it is good for the rest of the day. When I turn the choke on it doesn't work, pulled out the cable and sprayed carb cleaner down there, made no difference.
I have a 1980 citation 4500. How do you remove the cable from the piston valve. The cable seems to have a plate slid over the slot and I can’t get the cable to slide over to the larger opening where the larger lead end slides out. Hope that makes seance.
I have a 1978 Kawasaki KE 100 enduro and I am having a horrifying time setting the float height, either it overflows or it stalls upon load, also, what are the factory specs for the air screw? Thanks!
Please help. I have a brand new unused mikuni vm18. I removed the 4 screws on the float bowl. I cannot for the life of me separate the bowl from the upper half of the carb. It's like it's superglued on there even with the gasket. I cannot rejet until I separate the bowl. Any advice????
what does it mean when the snowmobile starts and runs only with the choke plunger removed. had to replace an old powerjet carb with a new vm roundslide, put brand new jets, needles, and screws in it. it only starts and runs with it out. if i put my finger over the plunger hole it sputters out. any suggestion????
1250cc This is old but it sounds like your jets need cleaned. Take it apart and clean it, and rejet if needed. It means that the fuel isn't going through the jets (or not enough of it is) so opening the choke let's the engine pull fuel directly from the float bowl. Clean the jets and and make sure float bowl drain screw is adjusted properly (may need to consult dealer or possibly find it in maintenance book) and if you still have issues it may need rebuilt. Cleaning jets should solve the issue though. You can do it yourself for probably $50-$70 or so, or have someone else do it for $150 or $200 (that's for rebuild). Cleaning you can do yourself for $6, and someone else will do it for $80 ish depending on their labor rates.
Firstly..Your video's have been very helpful.. Thank you.. Second, Please come out with # 5.. pertaining to setup. I recently replace carbs and cables on an older snowmobile and need to setup the initial adjustment for new choke and throttle cables, then need to sync and adjust to proper running and don't know where to start? can you help?
@@randywallis8190 Thanks for the reply. it was clogged main jet, at the bottom of the needle. I cleaned it pretty good, but I guess there was more junk hiding in the crevasse that worked loose once I started it up. Any recommendations on a cleaning solution for soaking the parts?
So I am changing for 2 Hitachi to a single mikuni on a Virago. I purchased a new needle jet that was listed for the carb and when I dropped it in it did not stick out at all. Besides being shorter everything else is correct, but I have not been able to find anyone who will explain the importance of the length of the needle jet.
I have a 1991 exciter 570, i cleaned the carbs and got it running after sitting for 2 years outside, it wont idle and is super boggy until i open it up it'll take off, i'm thinking i forgot to take the pilot jet out and clean them? could this be the problem?
I really learned a lot from this video. My favorite one in the series. I appreciate it!
@Polaris98ify yes for sure, clean carbs, make sure you get them synch'd, clean the fuel system as well.
The last time I ran my Jag, smartphones didn't exist and everything was trial and error. Now I know so much more. Thank you so much
make sure you clean the carbs the way i did it, if you dont you will melt a piston, also if you have made changes in clutching then yes you will run in to all kinds of other issues when trying to tune the system. don't just clean one thing, you can't clean without soaking the carbs, you can't clean without blowing them out with compressed air too. when done you need to synch the carbs, and you need to set the air screws to factory specs - if not youll be walking home:)
Very thorough explanation,..and to the point,..no vague areas !!!
@Polaris98ify for sure, clean them up and the fuel pump as well.
you need to take it right apart and blow out the passages and clean it, change the pilot jet and needle/seat. Set it to factory specs and it will run fine.
@nhbillybill Awesome - glad i could help!
A billion thanks Ishobie, this is exactly what I needed.
Great Video Series very use full keep up the good work,very simple and acurate explanations
Best explanation, that I've seen of Mikuni VM Carbs. Much needed, because they are prolific. Seems like they're in everything!
Btw: Not a big deal, but you might have mentioned, about how the idle screw works...
it just pushes the throttle valve up or down to adjust the idle.
if you havent changed anything then leave the jetting alone, you need to clean the carbs again and make sure you blow the passages out with compressed air. are the plugs dry from low throttle to 5000rpm or wet? if wet then its flooding, if dry then starving. I suspect a good cleaning will fix it up. Make sure those pilot jets are flowing properly and nothing stuck in there.
ask on the forums for what setting the carbs should be at - but dont waste your time unless you have cleaned them properly.
That is one way, I suggest downloading that manual and reading it - then look up piston wash on google for more info.
its kinda funny cuz i have a 1980 kawasaki drifter and i have the original shop manual for it to and in the manual it actually explains all of this in pretty good detail. but u did a really good job of explaining it so keep it up :)
if the carb is original to your sled then it should be fine, how does it run quarter, half and 3/4 throttle?
@appahman if the spark plugs are going white thats to lean when u have a nice toast colour then your running with the right mixture :) hope it helps
They should slide in with little to no force. they have to be lined up correctly though. make sure you didnt nick the jet or damage the carb body - if so just clean up the ear and try again.
Thanks to you for watching! Don't' forget to subscribe for more cool videos coming up!
Really nice work. I've got some issues Im stumped on with my kids Suzuki 50 3 wheeler. its got the tiny Mikuni 2 stroke carb that has been picky since day one. Now, Ive got it where it will only run with the choke lever all the way closed. I've tried adjusting the 2 mini headless screws to no avail. Any help is appreciated.
@kdrifter340 thanks!
measure the inside orifice of the carb where it slips into the carb adapter - that will tell you the size in mm's.
Excellent video , I have a VM 40 on a Yamaha YZ 490 85 and I really needed the useful informations on yor video
Ciao !
Wonderful video.. one of the best explanations on YT.. Thanks!
Glad it was helpful!
Excellent video and easy to understand. Thanks!
Thanks man! For someone just gettin into necking this was so helpful.
ya - you need to sort that out - i had no idea you changed the clutches.
The choke is used to let more gas in then air so the bike starts easier. I am pretty sure it is your main and pilot jets try going up by each size untill you feel that it is getting a good amount of gas and your spark plug has a nice coffee brown color. You will know when you have hit the right jets if your spark plug has a nice coffee brown color.
Yes, the needle is stuck open in the needle and seat - better take it apart and clean it up.
@Arcticcatteam Then you've had a good day.
What about the air jet that feeds the main . It's
Lines up with the main jet, the big hole on the air filter end. If you leave it out it will never run right.
ttttttttthank youuuuu! great video very comprehensive and understandable. this is exactly what I was looking for. cheers..
Thanks for the vids, very informative. One question, I took the needle jets out for cleaning but I'm having a hard time to get them back in. I've tried from the top as you mentioned with the groove lined up. Do these things go in with some force or should they slide right in. Any help or tool recommendations would be helpful... thanks!
Outstanding explanation
Thank you sir...we’ll briefed
Great video really well explained.
Thank you!
Geat vid. All the info i need in one clip, and well explained.thanks
My bike will only rev up with the chokes on, it won’t rev with them off. It just goes blahhhhhhhttt and dies. The plugs have always been very sooty and black, which tells me it’s too rich. Since the Mikuni starter circuit is different from a standard choke, is it giving me more air to the mixture while it’s on and throttle opened? Which is why it can then rev with the choke on? With the throttle closed, it will barely idle with the starter circuit on. Been chasing down the tuning with these carbs for weeks. Air screw is almost falling out to achieve a rise in rpms; I have smaller pilot jets on the way. Any help would be greatly appreciated. Honda 400cc with Mikuni VM 32’s.
thanks man, because of the gas issue i caught it on fire lol. just burned the fuel lines though.
Great vids, thanks for taking the time.
glad i could help!
How do you adjust the throttle slide valve?
Excellent Tutorial. Thank you!
Trying to get a 95 Timberwolf 250 to idle. My brother cleaned the carb and rebuilt with an "all balls racing" rebuild kit. Still won't idle. You mentioned the pilot screw doesn't need to be adjusted that much.. We put a muffler on the quad because the old one was all rusted. Him and his friend were trying to get it to idle and I remember him having the pilot screw 2 turns out and he was trying 2 1/2 etc. I've been reading into it and the manual says 1 1/4 turn for the pilot screw. If it doesn't idle at 1 1/4 turns out what else could we try?
Did some reading and going to check the float height and also drain the tank and put fresh gas. Other than that I have no idea what could cause it not to idle.
Lots of Mikuni's also use an Air Jet located inside of the intake venturi. I believe in your VM manual it is shown as item number 25. Can you explain how the Air Jet works in conjunction with the pilot jet and air mixture screw? Does changing the size of the air jet change the intake vacuum during starting allowing more or less fuel to enter?
Not with the pilot circuit. Strictly main circuit.
You'll have to read more on it. Just make sure it's clean an put in snug
Best video on here.thank you very much
I have a 1978 ke125 Kawasaki 2 stroke and come mukuni carb but cant find model number says mic that all
This is amazing. you have helped me out alot.
The spring that holds the needle jet in the seat do you leave that on or take it off when installing a carb kit ?
Hey thanks for watching!
I recently ordered a Mikuni VM16 Carburetor for 2 pit bikes and have been having issues with them. One of them came in and the bike would start, but it would only run on half or full choke even after being warmed up. Then, once warmed up, the bike would bog in the mid range and not be able to get to peak revs.
Also, when I turned the choke off, and tried to rev to keep it going, it would create tons of smoke.
On the second motor, it doesn't start at all. It just floods. Reset everything back to factory spec and let the engine sit and tried again and it flooded 5 times in a row in just 3 or 4 turn overs.
Can I get some help with tuning these?
So what way do i turn the air screw in or out for less air
Great Video! I have dual carb snowmobile but it floods the plugs first pull. When I pull the plugs and pull start it sprays and i mean its like a fountain of gas comes out. What would you guess the problem would be? THANKYOU!!!!!
Ok we need a newer mikuni break down and also the piston slide removal of say the 99 mxz 600
fantastic video . finally got it ! thank you very much :)
How does the bowl fill with that drain at the bottom of it?
great stuff but the float valve does not meter anything! it just ensures the bowl remains full but does not flood. as you say, the jets meter the fuel.
Great video very informative! Ive got a vm26 on a 79 jd trailfire 440 ive cleaned the carb very well I usually spend 2 to 6 hrs on these "I have 3 trailfires n have worked on many others" originally the sled was flooding basically while just sitting there, replaced needle n seat fixed that issue. now ive got a low end bogg, 1/2 a turn to 2 n 1/2 out on the air screw 2 n 1/2 out book says max although it seems to improve a little that far out. What do you recommend?
snowestonline, dootalk,snowmobilefanatics,etc etc
Hi good vid. I have a kawasaki 440 with a single carb but i can only get it to run if i live the shoke close just a little bit do you happen to know what could be the problem ( i clean up the carb two times just in case but maybe im missing something or adjusting something thank you and hope to hear from you soon
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.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?please help.Thanks.
Thank you for your videos. I am repairing a snowmobile and noticed that on carb has a what looks like a ball bearing in a tube that leads to where the choke plunger goes in. One of the two carbs is missing that ball bearing is that something I can or needs to be replaced?
How do you know too lean? just by the sparkplugs?
Hi l have the same mikuni carb on my skidoo elan , the question is , when a want add the choke , it is when l push or when i pull ? Thank you
So how does the idle adjustment screw work?
Help me out please I have the same Mikuni carb but I don't have a air screw, so where??
Can u plug the vacumn lines to gravity feed the fuel into the carb
Does raising the needl affe the rich an lean mix on idle?
replace your needle and seat - the needle is stuck open and gas is flowing thought it
Thanks for watching!
thank you for this video its been very helpful.
My -01 edge with flatslide carbs won't idle. Below 2500 rpm it just goes "boooow" and dies straight after. To lean mixture? The idle screw is at its bottom. I would appreciate your help :)
I have a 98 Summit x with the HAC deleted and oil pump deleted as well. the thing will idle but when I go anywhere near the throttle it bogs, won't rev and if I go to WOT it will die. its not the track (belt is off) and the fuel pump is working. I think it must be the carbs although the previous owner claims he just cleaned them last season...any ideas? I run 40:1 mix with 91 octane and ski doo oil
I have a problem with the choke not working, was hoping you would explain how it works, you only mentioned it once, guess it is not considered part of the carb.
W. Gator whats the problem with it?
It is like it is stuck, The dealer replaced the cable, and it worked for a while, but I have to prime it down the plug hole to get it started now and when it warms up it is good for the rest of the day. When I turn the choke on it doesn't work, pulled out the cable and sprayed carb cleaner down there, made no difference.
W. Gator I think you should replace the spring system if the Choke has one as they often do.
I have a 1980 citation 4500. How do you remove the cable from the piston valve. The cable seems to have a plate slid over the slot and I can’t get the cable to slide over to the larger opening where the larger lead end slides out. Hope that makes seance.
i didnt realy catch the factory air settings? gota watch it again great job brother
I have a 1978 Kawasaki KE 100 enduro and I am having a horrifying time setting the float height, either it overflows or it stalls upon load, also, what are the factory specs for the air screw? Thanks!
Please help. I have a brand new unused mikuni vm18. I removed the 4 screws on the float bowl. I cannot for the life of me separate the bowl from the upper half of the carb. It's like it's superglued on there even with the gasket. I cannot rejet until I separate the bowl. Any advice????
Do you have Any suggestions of where to get an oem pumper Mikuni carb or just a bowl for a 42A20 or 42A21 carb?
No sorry!
How could I know the size of mine??
awesome vid thanx I will be tearing mine out in the morning
Do you recomend a mikuni carb or Hitachi carburetor
i have a mikuni carb its off of a 80cc bike an i want to put it on a 66cc will it work
can a add a mikuni carb on a 212 cc predator on stage one ??
This carb is on an old Kawasaki 125cc 2 stroke motorbike I'm working on.
Shaine MacDonald what Care model is urs. im workin on a 73 sakki
Thomas bridges
I don't know. Where do you find the model number on it?
Shaine MacDonald shyte i dono lol was hopin u knew
Thomas bridges
My KLR has a keihin CVK carb in it and the serial number was under the float bowl cover
what is a nice carburetor I have to install to my rxz 135 I have the stock 26 mikuni. what should I replaced?
would a lean mixture cause overheating on rebuilt 440 polaris fan cooled ,my muffler just glows red after ten km.
Yes that is a very lean mix I'd check for vacuum leak at the intake manifold if the exhaust was not glowing before
what does it mean when the snowmobile starts and runs only with the choke plunger removed. had to replace an old powerjet carb with a new vm roundslide, put brand new jets, needles, and screws in it. it only starts and runs with it out. if i put my finger over the plunger hole it sputters out. any suggestion????
1250cc This is old but it sounds like your jets need cleaned. Take it apart and clean it, and rejet if needed. It means that the fuel isn't going through the jets (or not enough of it is) so opening the choke let's the engine pull fuel directly from the float bowl. Clean the jets and and make sure float bowl drain screw is adjusted properly (may need to consult dealer or possibly find it in maintenance book) and if you still have issues it may need rebuilt. Cleaning jets should solve the issue though. You can do it yourself for probably $50-$70 or so, or have someone else do it for $150 or $200 (that's for rebuild). Cleaning you can do yourself for $6, and someone else will do it for $80 ish depending on their labor rates.
Firstly..Your video's have been very helpful.. Thank you.. Second, Please come out with # 5.. pertaining to setup. I recently replace carbs and cables on an older snowmobile and need to setup the initial adjustment for new choke and throttle cables, then need to sync and adjust to proper running and don't know where to start? can you help?
I second that notion. I have a 1979 Arctic cat Jag that idles fine, but only runs on high speed if the choke's on. It's driving me crazy!
@@Xean45 sounds lean. Make sure theres no junk clogging the main circuit, and that its got a big enough jet
@@randywallis8190 Thanks for the reply. it was clogged main jet, at the bottom of the needle. I cleaned it pretty good, but I guess there was more junk hiding in the crevasse that worked loose once I started it up. Any recommendations on a cleaning solution for soaking the parts?
@@Xean45 sorry for the late reply
brakleen works good, and a compressor to blow it out
Gas is just pouring though my carb when my sled sits, its a 1996 polaris indy sport 440, do you have any clue whats wrong?
So I am changing for 2 Hitachi to a single mikuni on a Virago. I purchased a new needle jet that was listed for the carb and when I dropped it in it did not stick out at all. Besides being shorter everything else is correct, but I have not been able to find anyone who will explain the importance of the length of the needle jet.
What should I do if throttle valve stuck in top position when fully accelerate
get a stronger spring
can anyone make a video or give me a link about what a power jet is?
Good vid.Thanks.
I have a 1991 exciter 570, i cleaned the carbs and got it running after sitting for 2 years outside, it wont idle and is super boggy until i open it up it'll take off, i'm thinking i forgot to take the pilot jet out and clean them? could this be the problem?
quite possibly./
My choke plunged leaks What is wrong plz help
Is the coke on up or down
i have a carb thats all out wack whats the default settings so i get get it to start then fine tune from there.
1 3/4 turns out is starting point for stock air cleaner
question, if a 40mm mikuni carb is running rich and I add salt to the petrol, does a potato fall out of the washing machine?