4 Stroke Fuel Mixture Screw Adjustment
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- Опубліковано 4 вер 2024
- www.rockymount... - Having a hard time dialing in your fuel mixture screw? Jay Clark highlights some key points to look and listen for while adjusting your air screw on your 4 stroke carburetor. Carbureted 4 strokes can be dialed in nice with just a simple twist! After you've warmed up your bike a little bit, you can pull in the hot start lever and your bike should easily rev up. This is an indication that your fuel mixture screw is at the correct setting and that your bike's jetting is good. Get dialed in with the Tusk Fuel Mixture Screw, available at RockyMountainATVMC.com!
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/ @rmatvmc
I was skeptical at first because I have tired everything to fix my hanging idle. But the hot start method really works, now my bike is running like a dream. Thanks!
Who else doesn't have a HOT START on their bike?😭
My poor 1980 xl 185
What's a hot start?
8 years later this video is still helpful. Thank you.
Glad it's still helpful! Thanks for checking it out and leaving a comment.
@@rmatvmcg'day man I thought that was the decompression lever and was not supposed to be pulled in while engine was running I have a KTM 450 e x c racing engine I never pull that lever in my understanding of it is is it for when you kickstart and you want to lose a bit of compression to make it easier for you to start it but you should not be pulled in my bike is running but I don't know if you could help I would be very grateful I know it's been a quite a long time but if you're still out there please let me know cheers from AUS🇦🇺
In the old days, before hot start and such, we used to:
First make sure the air filter you are going to use is clean, dry and installed.
1-set the mixture screw at 1.5 turns out.
2- start & warm the engine.
3- adjust the mixture screw out (or in) 1/4 turn at a time looking for increase in idle. If the idle increase too much, turn the idle down as low as it will go and stay running.
4- keep adjusting the mixture screw until you find the best idle, then re-adjust the idle to where you want it.
Question(s):
a- Is that correct for a none hot start carb/bike?
b- Is that a good starting point even for a hot start carb/bike?
c- Wouldn't the needle height have some bearing on this adjustment?
Thanks for the tip man nice easy way to determine the Fuel mixture
Bikes been running like shit and lean popping for a year now finally got fed up and looked for a mixture screw and did what was in the video and my god it’s a different bike it idles now and runs like a dream but I did have to back it out more than 3 times or around 3 times so I’ll have to get a new pilot jet like mentioned but as of now it’s working great
great video man, simple adjust.... thx a lot, helped me!
hi i have a 4 stroke scooter and i put new exhaust on and its running extremely lean what would you recommend I do ?
Isn't that the decompression lever I thought you weren't supposed to pull that in while the bike was running please advise
Awesome video 👍👍 thank you so much!!
Can an aftermarket fuel screw be the wrong size? I changed to one from Amazon and I'm 3.5 turns out. I rebuilt my carburetor using all factory jets.
My hot start doesnt change the idle in when I move the needle in any position
At night my exhaust pipe right out of the engine is cherry red during normal ride? Is that normal on 06 honda crf250r?
You ever figure out what the problem was?
My 2007 crf450r won’t start. I just cleaned the carb and I don’t know where the fuel screw should be
If its never been adjusted sometimes there is a little cap over it that you have to take out and discard.
Thank u sir saved my ass
If, the rpm Rose while applying the choke, that should be correct afr mixture? Please, reply.
Sir, recently I had clean my bike engine head, after that, bike didn't start in cool without using choke and clogged running in up to 1 km.what is the reason please reply .
Will you have to adjust the screw if you get a big bore? I have a 250f big bored to a 290 and the hot start lever doesn't work for me anymore
Sir, why does my bike starts applying on choke in cool engine. Please, reply.
What screws? Didnt show anything so I assume the air/fuel screws
You are correct, we were meaning the air/fuel screws.
How many turns out is the stock setting please
Stock for this model is 2-1/4 turns out. Be sure to refer to your service manual for your machine specifics.
I love this man
Mine is out 3 turns, no matter where it is the hot start pulled kills the bike. It's all factory jets carb was cleaned and all 5 jets cleaned.
what if i dont have hot start
Then i take assumption that your fuel injected and not carbureted?
TTR 230
Electric start only and carb
Huh, idk ive only messed with race bikes (crf250r's)
BDSVM Yea.. no hot start here either, on my '09 WR250F... the previous owner raced the bike and did a bunch of mods which included removing the hot start lever. The bike runs very strong and has never failed me ever. But plan on going to Moab and need to do some rejetting....
basherdesigns Sweet trail machine. Should perform nicely down in Moab, UT.
i have hot start either......got to be fancy
background looks a lot like Johnson Valley
Will a bike running to rich overheat
Yes.. Sorry im 3 years late
My fuel screw is set perfectly at 1 and 1/4 turns out but doesn't rev like that with hot start, how it this possible
yes because mine does it too
what if no matter how many turns you are on the fuel mixture screw the hot start makes it die where do i start?
The only way it will rev up by hitting the hot start is if the choke is on so does that mean it is running to lean?
nice green screen
I have wr450 2004 2 turns out revs a bit but not strong bit better at 3, i have 48 pilot which is already large, if i go richer in needle or main or leak jet will it fix this?
Cleaned my carb on my 07 TTR 230 and it runs fine wont backfire but wont idle, any ideas?
Did you take completely out your pilot jet and main jet to clean? There are little pilot holes on the pilot jet that need to be cleaned out if clogged up with debris. Can you see clearly all the way through the jet? I would recommend you check that. When cleaning a carburetor I like to spray carb cleaner down every hole/port to ensure that nothing is gummed up or blocked. You can check your air fuel screw positioning as well, your service manual will specify how many turns in/out it needs to be seated to. Let us know what you find out. Thanks
I turn the fuel screw all they way in and at some point motor dies, push hot start doesnt idle high what shall i do with my pilot??
You want to have the fuel screw backed out at least a half turn or more up to 3 turns out. If it's still not working, you may need a bigger or smaller pilot jet according to what Jay explains in the video.
Good stuff. I know ZERO about newer bikes. I can rebuild a Water Buffalo or H2 in my sleep ;-) NO~NO. A real H2. Not that newfangled crap.
Turn the music up louder I could almost hear you.
so I'm having an interesting issue. Just got a used 06 crf450r, so I can turn the mixture screw all the way in and the bike will still run. About 1 1/2 turns from full out before it wants to die. I have it set at the point my hot start will make the idle raise but screw it in any more and it'll cut the motor once the hot start is maxed out. Do I need to go down a size for my pilot jet because it's still running while screwed all the way in? Or am I set okay because at full in the hot start kills the motor?
I have the same issue..? what was the fix?
Answer for both of you is a ''Bigger jet ''and then the perfect spot must be between 1 1/2 - 2 1/2 :)
I have a honda 150 crf and it is idle up real high and anything I do it won't go down what do I do ??
Check your throttle cable, maybe?
Cory Agent I have a 150R make sure ur choke is not engaged and your idle cable actually works. if it's not that check if it's running too rich
And if you don’t have a hot start button on your 4 stroke?
that means you have fuel injector and don't care about all these "magic" :D But sometimes, people just install plug on hot start valve in carb, so - that's bad idea.
Remember if it's very cold outside your air mixture will be lean, Also don't cut your air box or you will need to rejet your whole bike Main and pilot.You won't get that much horse power from your motor and you motor won't last as long.
I have a dirtbike an when you start it it won't stay on unless you rev it. Carbs clean an I tried adjusting idle. An it dies when you take choke off what could be up
+Sean Fitzgerald Jr It could be a number of different things causing the problem but it sounds like the engine isn't getting enough fuel. Usually when the engine won't idle but it has idled fine in the past then chances are your pilot jet is clogged or plugged. I would check that first and then work from there. Have you changed jetting recently?
Rocky Mountain ATV MC the jets are like new. And cleaned out so it can't be that
+Sean Fitzgerald Jr Have you changed any jet sizes or made carb adjustments recently where before it ran fan? Also how old is the gas going through the carb?
All I did was clean the carb. I actually just fixed it had to adjust the idle a fuel mixture. The only problem now is when you take the choke off the bike wants to start moving forward
+Sean Fitzgerald Jr That would be either a clutch cable adjustment needed done, or a new clutch kit.
Idle*
I have a 125 4 stroke that been sitting for awhile since a chain link broke on me. it had old bad gas in it, I drained it all out and put new in, it fired up fine yesterday but didn't ride it. today I replaced the chain link and was going to ride it but I couldn't get it started to save my life. have no idea why it isn't starting now, help me out?
More than likely it's going to be a simple deep cleaning is all it will need on the carburetor to get her running again. Best bet is you have some gunk clogging up the jets. (main & pilot).
+Rocky Mountain ATV MC that's what I was kinda thinking, just didn't do it today lol. thanks for replying!
You're welcome! Good luck.. let us know what ya find out.
+Rocky Mountain ATV MC I took the car off, pulled it apart and cleaned it. everything looked fine jets weren't clogged. it still will not start. check my spark plug, that looked fine. I'm getting fuel to the car it just doesn't seem like its trying to ignite at all. I don't know what the problem is.
+Matthew took the car off*
My wr450 2004 almost 3 turns out and needs more to have a stronger rev, i already have a larger pilot 48, needle and main dont have much effect on idle what i do?
If the fuel screw isn't effecting much, your pilot is probably off. you may be too rich.
Rocky Mountain ATV MC if i turn all the way in it stalls like it should at 2 turns bike is fine but hot start rev is not so strong ,3 slightly better
@@SnipingWithSkillz hey man im having same problem with my supermoto 2004 WR450 almost 3.5 turns out and already has a bigger pilot and stuff. Don't know what to do idle is hanging hard its lean
@@wr450sm5 there is a mid carb gasket in the middle
@@SnipingWithSkillz is that gasket in the middle known to go bad?
So if your pilot screw can be adjusted more than 3 turns out you need to go with a larger pilot jet or pilot screw?
+SlammedBeretta Pilot jet
+Rocky Mountain ATV MC You guys are awesome.
where is the screw
Check out our video: Tusk Fuel Mixture Screw install and setup | ua-cam.com/video/fP-8Q_Nqtc4/v-deo.html
what about on fuel injected engines
On fuel injected bikes, some bikes you can adjust the idle screw/choke but you won't have an air screw on FE bikes. The computer does all that for you.
Rocky Mountain ATV MC oh ok thx
what if the revs go to high ?
Ricardo Cuetara everything I've researched said "by adjusting your idle screw; bring your idle down to a little below normal running idle after your bike is good and warm. Then start with your fuel screw at one and a half turns out make sure you seat it first but be careful the tip on the fuel screw is delicate. But start from there and work with quarter turns only and you should find that perfect balance
Jamie Brasnyo.... Thank you very much!
What about the thousands of bikes that don't have the hot start
My bike dies either way i turn it
What if you start your bike with a choke and you take the choke off and the bike doesn't want to ideal because I can't give it has with it wanting to die. It sounds like when give it gas it's not getting air
I'd start by turning your idle screw up just a pinch, even before that make sure you have a nice clean and oiled air filter.
I had the same problem, turned the idle up just a bit and it idled without the choke, otherwise it just wanted to die without the choke on. After that I bought one of these pilot screws they have in this video and it made it extremely easy to adjust vs. trying to get a screw driver in there.
What does he mean pilot jet?
😊😅
What I'm not getting is these machined aluminum pilots don't tell you what size they are. So say I'm at 45 and think I need a 42, how would I know it's not a 45?
+Triston Charge All pilot jets will have the size etched in on the side.. You may need to clean it up a little better in order to see it?
I meant the new ones that you show. The easy adjustables. They don't say what size they are...
+Triston Charge Our air fuel mixture screws do not have a set size like a 42.5 or 45. They're fully adjustable to help you fine tune your carburetor without using a special screwdriver. These Air Fuel Mixture Screws are generally turned out 2-3 complete turns.
Rocky Mountain ATV MC Oh ok, so basically they're universal as far as the settings go, awesome!
Triston Charge Exactly! ☺
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Talk talk talk
No sound. Thumbs down!!
Not all 4 strokes have a hot start so this was not helpful AT ALL for most of us. No thanks
Fu***ng commercial!!!