Know how to adjust air/fuel mixture screws on ANY carburetor in 30 seconds!

Here's a quick trick to know which way to turn those fickle air fuel screws just by looking at any carb body! #shorts
Subscribe for the upcoming complete series on carb components and functions!

[@iuopunderstandyourjokes9914]

This was the best and shortest explanation ever

[@oneupmotogarage]

thank you

[@SparkzOT]

Forreal bro I'm tired of ppl acting like carbs are so hard. All I needed was some youtube. Got the 2 stroke stroking now

[@iuopunderstandyourjokes9914]

@@SparkzOT i used this to make my mercedes 280s run ok-ish

[@zejjezoberez1545]

Nice explanation Sir.

[@azetorajoseph6814]

I think this is the only best explanation about the meaning of adjustment on carburetor I have search for long on utube. thnx for ur good summarized work

[@chadmills5400]

He got it backwards unless he is saying it wrong. A carb adjusts air not fuel, so you can only run rich/lean on air. He could get peoples engine blown up doing it the wrong way!

[@mrbubbles4242]

Bro this helped me so much, I’m currently restoring an old moto4 (200cc) and I had to get a new carb and have no idea how to tune it until now

[@zovards2089]

@@chadmills5400 so are you saying the carburetors with two adjustable screws are both for air I don’t think so buddy

[@willgamer0849]

​@@zovards2089My carb only has one screw on the engine side at the bottom. If I loosen it is richer and tighten leaner? I can't find the sweet spot between both. it idles well but sometimes it does little backfires when downshifting.

[@theamaturepro]

Well son of a dang, I learned something on youtube. Now I'm cool like the young people.

[@oneupmotogarage]

sweet

[@joeecarbonee6849]

Yeah me to man 👍

[@SparkzOT]

Hell yea brother

[@charlesburk8636]

Good job getting straight to the point and explaining clearly. Thanks

[@Jursaw]

Not always the case. Best way to tell is to remove the screw completely and if it has a fine point then it is a fuel screw. If it has a blunt point then it is a air screw.

[@oneupmotogarage]

Have an example of when my trick doesn't apply? Yes checking the screw works too but is more invasive/ takes more time/ requires a tool.

[@Jursaw]

@@oneupmotogarage that is true and yz85 and kx85 carb. Screw is on engine side but it is air screw

[@oneupmotogarage]

@@Jursaw What years? Images I'm googling show carbs with air screws on airbox side.

[@Jursaw]

@@oneupmotogarage my apologies, i meant ssr70- im working on a few different bikes at the moment

[@oneupmotogarage]

@@Jursaw don’t those use knockoff keihin carbs copying the PD series from Honda’s smaller XR/ CRF’s? They should have air adjusting screws on the airbox side of the carb.

[@patricklardieri1796]

It had been twenty plus years since I had been on a bike!!! I ride two strokes and my bike was idling really really high. I had changed the reed cage and reeds and couldn’t figure it out. This video told me exactly what I needed to know and I thank u for this video!!!

[@psylentsage]

Wow quick and to the point perfectly explained 👍🏼

[@oneupmotogarage]

Thank ya!

[@Joshtheweatherman]

At sea surface levels or slightly above, usually 1, 1/2 turn out is good enough. The higher up you are, the more you’ll have to turn out.

[@ShivasishKhan]

i have bajaj pulsar 135ls 2018. the rpm screw is to the right and idk a screw is near the engine in the left side. what screw it is...

[@thelikebutton4405]

Not always the case. A lot of carbed motors are just idle air mixture screws with fixed jets.

[@larrybenedict6293]

Best, quick and simple explanation yet 👍!

[@thomasd9237]

Straight up to the point & brilliant explanation 👍👍

[@oneupmotogarage]

thank ya 🙏

[@TheGrimFoot]

I watched it 12 times to make sure I remember

[@str8xrippin]

Mine is on the outside by the intake and i loosened it to the very end and oh my word the amount of engine response and power it suddenly had. The bike used to stumble whenever im taking off it would only run about right when im at about 2500 - 3000RPM but now its so smooth and it pulls hard im so shocked

[@bunchesofoats2051]

....this gives me...tooo much confidence

[@marcusstenberg1452]

Very useful

[@Unkyneurons]

This is a good explanation thank you

[@oneupmotogarage]

🙏

[@benderbender1233]

🤘

[@la_plata3588]

Remember if your adjusting these without the airbox you need to start over 😅with the airbox

[@oneupmotogarage]

@@la_plata3588 yea that can make a difference! Though at idle the airbox’s influence is minimal.

[@jenriej.bandajon7933]

Best explanation ever

[@Galaxieshop]

Shout to u! 📈📈👌👌

[@oneupmotogarage]

🙏

[@AlexandraMunda]

I want to learn more about carburator explaination

[@raka2844]

This is probably stupid question since i just started but How do you know if you had too much air, or too much fuel / less fuel and less air?

[@oneupmotogarage]

It's a good question and the truth is it's very hard to tell without an O2 sensor. By feel you learn the subtle differences in how the idle will sound when too rich vs too lean. There's usually a crackle or pops on deceleration if too lean, if it idles high or idle hangs, usually too lean. Vs if after revving the idle drops too low and then slowly comes back up to the set idle, that's a sign of too rich. I'll try to do a vid detailing that someday.

[@raka2844]

@@oneupmotogarage thanks!

[@Pepper_Mint_]

This is some serious information who owns an old vehicle...since we are in Fuel injection era

[@jeremyw9098]

Even newer bikes have carbs. I just bought a 2023 motorcycle with a carb.

[@TylergoinLIVE]

Str8 to da facts wit a understandable explanation 😂

[@DonnieToys]

I tell you, Nay: but, except ye repent, ye shall all likewise perish. (Luke 13:5) But we are all as an unclean thing, and all our righteousnesses are as filthy rags; and we all do fade as a leaf; and our iniquities, like the wind, have taken us away. (Isaiah 64:6) As it is written, There is none righteous, no, not one: There is none that understandeth, there is none that seeketh after God. They are all gone out of the way, they are together become unprofitable; there is none that doeth good, no, not one. (Romans 3:10-12)

[@RyyFoo]

The carb on the right, what does the screw in the middle with the spring on it do?

[@oneupmotogarage]

That is the idle adjustment screw. It directly moves the resting position of the slide up and down to control idle.

[@RyyFoo]

@@oneupmotogarage thanks

[@tokazishiki6051]

👍👍

[@jacklord1580]

I love how this video debunked myths about carbs like in seconds❤

[@nobodyonline8454]

Thanks man I always knew that i needed to use that clscrew to adjust the carb but for the longest time i couldnt figure out witch way was more fuel and witch way was less fuel

[@oneupmotogarage]

glad I could help!

[@NOCALLERID72]

So when I go to full throttle my mini bike is kinda backfires but it’s like a rapid backfire and sounds like it’s stuck and doesn’t want to move any faster than it does after that. Any advice?

[@JustinNeill-z8k]

Thanks! This helps a lot

[@oneupmotogarage]

@@JustinNeill-z8k love to hear it!

[@KaloyanBeshev]

Best explanation, thank you!

[@buhaypantra862]

Very helpful! Thankssss ♥️♥️

[@oneupmotogarage]

love to hear it!

[@calebchiu747]

Newbie question, but does anyone know if it's ok to adjust the screw while the engine is running?

[@juliusnjinja3441]

Simple and clear

[@reyebans9094]

Thank you

[@brianb5779]

I like that fuel graph chart you showed. Is there a site I could get a printed copy or just a good snapshot of that.

[@matrolen]

Pause the video when the chart comes up. If youre on a phone screenshot, if youre ok Windows, windows button + Shift + S for the Snippet tool

[@brianb5779]

@@matrolen thank you

[@Pork-Chopper]

Ahh shit! Just screw it! 😳

[@zacharydewitte384]

Future me says your a G for this . Like so I can come back after I get a Mx bike again

[@jessejarzabski5076]

All my 38mm keihin 2 stroke carbs have the air screw on the left side of the carb with the air screw on the right hand side, which would be the air filter side and not the engine side right?

[@oneupmotogarage]

Yes, what you describe is common among 2 strokes. With the mixture screw on the airbox side so they control air (out is more air = leaner, in is less air = richer).

[@Outdoors-and-Sports]

What if its at the bottom of the carb dead center?

[@illusion-vipxr5820]

I can't even find the screws on my bike

[@GForceGames1]

I have a Mikuni BS32SS and the screw is on the engine side. However it acts the opposite as described in the video?

[@oneupmotogarage]

How is it acting like an air bleed screw? On those BS32's the screw is on the bottom of the carb right? You usually start at 2.5 turns out from lightly seated (it's easy to break the tip off that particular screw type). Loosening it from that setting will add fuel = richen mixture, tightening it will restrict fuel = lean mixture out.

[@GForceGames1]

​@oneupmotogarage (screw on top, set of 4 inline) I started out at 1.5 turns and bike acted super lean. Would idle good with choke on, rpm would rise at idle when bike gets to running temp. I moved it to 2.5 turns. Idles a lot better but misfires until it's warm. Still playing around with it. I do believe you were correct and I misdiagnosed my issue. Also also, the screw itself goes super deep into the carb. It looks like the flat side carb , but the screw doesn't petrude like that. It's fairly deep into the carb. I appreciate any help, due to not much information that I can find on this. It rubs best at 3.5 turns out, but idles low when cold, idles high when warm but runs great

[@oneupmotogarage]

@@GForceGames1 the deep recessed screw is normal on street legal bikes by the 80's due to EPA requiring an anti tamper plug to be installed over all air/ fuel mixture screws. Off-road bikes and aftermarket carbs usually have the screw sticking out more for easy access. You can also buy longer screws to replace yours to adjust them more easily if you like. 3.5 turns out is an acceptable setting, once you get past 4 turns it means you need to go up a size on the pilot jet. But unless the engine is bored over or other big mods I never have found a need to change pilot sizes.

[@oneupmotogarage]

@@GForceGames1 When an engine is cold it runs lean and as it warms up it richens. That's what a choke (usually an enrichment circuit on newer engines) is accounting for. So generally if the engine runs well when cold and then starts to struggle once warmed up, it's tuned too rich. If it really struggles when cold and gets better as it warms up, it's too lean. But there is some expectation for a cold engine to struggle (run a little lean) when tuned correctly, hence why they add chokes to help it warm up, then once warm it should be operating its best.

[@GForceGames1]

@oneupmotogarage You're a G! I think I will end up ordering new carbs. I'll tear these down to learn more about carbs myself. I think 3 was the best, it seems my air filter (factory enclosed box) was a tad loose, had to fix that and take some fuel out. Idles great now, runs decent enough to not worry about anymore. I appreciate you a whole lot. I subscribed just because you're helpful!

[@Gunner0331]

What if it’s literally right in the middle of the carb ? My motoku carb for my 2006 Honda 250ex is

[@oneupmotogarage]

@@Gunner0331 then it’s the idle control screw. Tightening raises the slide/ idle, loosening lowers it.

[@joeecarbonee6849]

Heck yeah that helped big time. I always wondered 👍👍

[@oneupmotogarage]

awesome!

[@chuckhuff7123]

They both act the same ways. All your doing is confusing people. They are the same people, two thumbs 👍 down for this genus 😮😅.

[@oneupmotogarage]

Watch the video again...

[@rv_316]

superb... 👌👍👍🙏🏻💝💖🌹🌷🌺🏵️🌼🌻.

[@sumitpatel2900]

Tighten - lean Loose. - rich

[@papercut1987]

can you do a comparison between TM and VM? i 'm not sure which to get for Yamaha XS850

[@oneupmotogarage]

Great idea! In the meantime in short, it's a tough call because they both have advantages. VM is cheaper/ easier to tune, but TM has a better performance potential.

[@chase_playz8238]

Question this the same for a mini bike carb

[@TheWorld-of7dd]

I was looking for this, tq

[@chalo212]

My bike doesnt bog at all but it takes a while for the revs to go down.... Im thinking less throttle valvue, right?

[@oneupmotogarage]

That’s usually either an air leak (on engine side of carb), idle set a bit too high, or lean air/ fuel mixture or pilot jet.

[@tylermontano4891]

What if there’s only 1 screw and it’s dead in the middle, got a 80cc Suzuki quadsport and don’t know it’s it just an idle adjustment

[@oneupmotogarage]

The screw in the middle is the idle adjustment, it directly raises and lowers the slide. The stock LT80 carb does not have an air fuel mixture screw. Which is fairly rare. But aftermarket options for it do. The stock carb works well without it so I'd say don't sweat it.

[@Ilikebaseball770]

Very helpful thank you 🙏

[@kanishka.b8550]

Well this is not accurate at all. Sorry. It may be true for most but every carburetor is not like this. Can change. I adjusted my carburetor according to this and I got a bogging problem I can't get rid of. I even removed the head to check for valve leakages. Then I came across a video which showed how to determine the screw according to the shape of the end. Air screw is blunt on end and a fuel screw is pointy at the end. Mine was blunt and on further inspection I found that the screw is actually in the middle of the air channel even though it was on engine side... Beaware guys. Not everything is what it seems.

[@oneupmotogarage]

@@kanishka.b8550 There are exceptions to every rule. I know of carbs that the tip would mislead you on too. So far I have only found 3 carbs in existence that don’t follow the rule I outline in this short. If yours doesn’t apply maybe you’re tuning the Mikuni PZ19 which is the rare exception with an air bleed on engine side. There’s no way you could have adjusted your screw according to this video in a way that you couldn’t undo by resetting to where you started. If a persistent bog has shown up, at worst your plug may be fouling if you ran it too rich for a while.

[@electricianslife1984]

Thank you brother

[@grantleypotts8046]

Excellent information but I was hoping that you would explain how to set the metering needle height for the correct air fuel mixture.

[@oneupmotogarage]

Yea I'll definitely be doing more in depth carb set up vids in the future. And the needle/ emulsion tube will be the focus of one.

[@4legdfishman]

Great explanation! New subscriber!

[@Altie8]

this helped

[@reesemolloy6109]

Hey quick question my lawn Tractor will only run if it’s on half choke how do I fix that?

[@oneupmotogarage]

usually that's because the pilot jet is clogged. I'll do a vid on how I clean those out someday soon.

[@DerrickChiiya]

Watching form Zambia

[@raylendrazel8471]

same on 2 stroke carburetor? tighten : lean loosen : rich plz reply😢

[@oneupmotogarage]

The same rule applies to 2 stroke carbs. Usually 2 strokes have the screw on the airbox side metering air so in = rich and out = lean. But if your screw is on the engine side of the slide, it will be like you say.

[@arnoldcastillo9967]

Is air supposed to come through these screws? I sprayed some carb cleaner in my nibbi carb and some came out the screw . Bike won’t start and I’m wondering if that could be the culprit

[@oneupmotogarage]

If it is an air bleed screw, then yes, if it is a fuel metering screw, then no. But if it's a fuel screw and you spray cleaner into the pilot jet then it will come out of the fuel screw, because that is the path the fuel takes.

[@edwinmendija8087]

THANK YOU!!!!!!

[@oneupmotogarage]

You're welcome!

[@easytomove]

Make carburetor great again

[@Umam635]

Ngecepek gak paham aku yo

[@Jagruknagrik-2024]

But can u explain how the air side screw when turned in os lean?

[@oneupmotogarage]

It's the other way around, on the air screw turn in = rich, loosen = lean.

[@Ryantomada-e8h]

Thank you for making this videos need more people getting straight to the point😂

[@oneupmotogarage]

I appreciate it!

[@tonysanchez4519]

Gr8 video. thank you!

[@oneupmotogarage]

thanks

[@Hunter-g5w]

Thank you for this video I have watch other videos and this one is the best and it's only 30 seconds.❤

[@mosermotors]

PLEASE HELP. I've been told for my bike the Goal is to be out 3/4 turn. It's been set at out 2 and 1/8 for the last 40 hrs. If I shoot for 3/4 will that make it it run way too rich? I'm already fouling plugs as is if I idle too long which is why I'm looking into setting it correctly.

[@oneupmotogarage]

Am I right to assume it is an air mixture screw? Meaning 2 turns out is leaner (more air) than 3/4 turns out. If that's the case and even at 2 turns out it will foul plugs, then it sounds like you need to go down a size on the pilot jet to lean the pilot circuit out more than the mixture screw is able to. You may end up two sizes down on the pilot jet to get it running well with the mixture screw only 3/4 turns out.

[@mosermotors]

@oneupmotogarage you are correct, air mix screw. Okay so it's time to Jet it. Thank you for the reply 🙏

[@demekamitchell404]

😂 loosening means it more leaner and turning in make it more rich mix he has it backwards

[@oneupmotogarage]

Unless you’re talking about some older Concentric Amal carbs. No, I don’t. You’ve misunderstood the video.

[@Wanted1fiddy_r]

Does this also apply to a 2008 crf150r?

[@oneupmotogarage]

Yes on that bike the screw is on the bottom of the carb, engine side of the slide and it is a fuel mixture screw so turning in = lean and turning out = rich.

[@nickroutzahn4343]

My bike runs fine but when it idle after a few seconds it cuts out any suggestions

[@oneupmotogarage]

My first guess would be too rich on the idle circuit. You can try adjusting the air/ fuel screw to lean it and if that doesn't help, try richening it.

[@harleymcmurran321]

That is correct alot of the time but not always, sometimes it's opposite And some have both

[@oneupmotogarage]

I've found about 3 carbs this doesn't apply to (PZ19, concentric Amal, and maybe an early /2 BMW Bing). I know of one carb that has both, the KZ1300.

[@pochuanhsing2466]

Nice job on the finding. Will be useful for my next project, I just need to clean up a gas gumed carburetor from Honda shadow. Technician said will cost me 5-600 to clean on the bike now.

[@oneupmotogarage]

I love Honda shadow's, what size is yours?

[@pochuanhsing2466]

@@oneupmotogarage thanks VLX 600

[@chrisflores6256]

Just those screws??

[@Splitshot1]

What of the screw is on the bottom of the carb like the one on my 2000 suzuki quadmaster 500.

[@oneupmotogarage]

The screws can be any number of places on the carb. Top, vs side, vs bottom. Either way just note when looking at the side of the carb, is the screw closer to the engine or closer to the airbox- relative to the carb’s slide? Usually ones on the top and bottom are fuel metering screws, and are closer to the engine.

[@Splitshot1]

@@oneupmotogarage Thanks so much for the response.

[@devinfulkerson3220]

carbs make me so mad

[@aaronr-cw4rl]

Does the air one make my 140cc dirt bike pop I want it

[@oneupmotogarage]

Popping on decel means too lean. Either screw can make it do that if turned in the respective lean direction. But why?

[@colesmile3028]

what if the screw is in the middle?

[@oneupmotogarage]

In that case it is actually the idle control screw. Meaning it directly raises and lowers the throttle slide. Tighten to raise idle, loosen to lower.

[@greatmoose17]

I have the plastic screw heads on TM40’s on my Snowmobile and I went from 1.5 turns (spec) to 2 turns thinking they controlled air. Now it floods out at idle and is really hard to start when warm. I guess those screws control fuel and not air on the TM40’s. Can you confirm this? Thanks for a great video. Subscribed.

[@0vixie0]

Whats better? More air flow or less

[@oneupmotogarage]

Neither, you want the perfect balance. Too much or too little will both cause poor running.

[@mikebenson1104]

when installing..which comes first...the washer or the seal before the spring..??

[@oneupmotogarage]

Great question! I see this installed wrong all the time. It goes: needle-spring-washer-oring. You can remember it by thinking of the job the washer does, it protects the oring from the rotation of the spring when tighten/ adjusting.

[@jack_9261]

When fine tuning, should we do it to one screw or to both? If so, which should we statt with ?

[@oneupmotogarage]

A carb will only have one mixture adjustment screw. Very rarely will they have 2. Starting points depend on the carb, usually if it is a fuel metering screw you start at 2.5 turns out from lightly seated. If it's an air bleed screw then you start them at 1 turn out from seated.

[@PinnedTTR125]

What if its in the middle

[@oneupmotogarage]

in the middle is the idle adjustment screw

[@PinnedTTR125]

@@oneupmotogarage The TTR 125 carbs don't have idle screws. Their mixture is how they change the idle

[@PinnedTTR125]

@@oneupmotogarage cuz the idle is set in stone so the mixture is what you adjust idle with.

[@oneupmotogarage]

@@PinnedTTR125 They most certainly do have an idle adjustment screw. But on that carb it’s not the screw in the middle. That is actually not a screw, it is a guide for the throttle slide. You can’t (or shouldn’t) move it even though it looks like a flat head screw. The mixture screw is on the engine side under the carb (meter’s fuel), it may be covered by a little plug you have to remove.

[@PinnedTTR125]

@@oneupmotogarage I had to move it the other day because of a adjustment to my air box that caused it to backfire and idle low and I turned that screw and both problems where fixed

[@Nizzo1x]

Yioo

[@DerrickChiiya]

🎉u re the best

[@galenmarek8287]

Great explanation, but I also noticed that the carb on the right also has another screw right dab in the middle. Does that mean that carb has an air adjustment AND a fuel adjustment?

[@oneupmotogarage]

@@galenmarek8287 that screw is the idle control on that one.

[@galenmarek8287]

@@oneupmotogarage Roger that. I’m new to bikes but I’ve been ankle deep into cars, trucks and tractors my whole life. Many thanks.

[@mamichulo9982]

dang bro. i finally found the answer to the long time question in my mind. i have the xr 200 motorcycle and i was not sure how to adjust the carb. thanks so much!

[@oneupmotogarage]

perfect! I think those run the Keihin carbs that I did another video comparing the genuine vs cheap Chinese knock off.

[@elvisramos2660]

What if there’s two needles on the engine side?

[@oneupmotogarage]

@@elvisramos2660 did you mean to say needles? I've never seen one carb have multiple needles. Did you mean to say two screws on the engine side?

[@elvisramos2660]

@@oneupmotogarage I think there screws there’s one under the throttle which I’m guessing is the fuel one and one on top that is for flat screwdrivers and the idle screw which is for the throttle

[@elvisramos2660]

@@mamichulo9982 it’s a carb from a arctic cat 300 4x4

[@maximjimenez303]

So how do I know if I tighten/loosen the screw too much?

[@oneupmotogarage]

It won’t run well! Usually if you’re more than 3-1/2 turns from seated you’re too far out. And if you’re less than 1/2 turn from seated you’re too far in. If it needs to be outside of those boundaries, your pilot jet needs to be bigger or smaller.

[@leo959]

What about that other screw in the middle?

[@oneupmotogarage]

middle screw is idle control

[@99Yeti]

I prefer the owners manual sometimes

[@MaldonadoMoto]

Thx this helped a lot!

[@oneupmotogarage]

awesome

[@chrisflores6256]

Pm

[@teenice894]

So confusing to me.... 87 Honda elite 50 and new to 2 strokes... can't get screws right 😢

[@redneck94chevy]

Ive heard that air screws are more sensitive to adjustments than fuel screws are. Would make sense since that the perfect ratio is 14.7:1. Seems like adding more or less air would have more dramatic effect than fuel would

[@n8rbos]

Well I learnt something today..many thanks.

[@Mrpuggo0322]

I do it while the engines running. Then i can hear if to much or to little fuel is going in