How-To: 4 Stroke MX Fuel Screw Adjustment YZF CRF KXF RMZ FCR Part 1 of 2

[@HTMR]

The idle should be low when making the adjustment, it helps notice RPM change. I bumped up the idle to 1900 at the end since that is what recommended setting is (1800-2200?)

[@JeepinBoon]

I feel a lot better about my newly acquired 09 YZ250F now. These bikes naturally make unnatural noises and run like crap at idle. Make it run smooth at idle and it dies at instant WOT under load. Yamaha minimized rotating weight for max hp, and it's impressive. Very impressive. But don't plan on a Honda CRF100 style cruise around the catfish pond, the YZ250F is fast and mean.

[@milwaukeeaterfu2190]

and the first alum frame years are the worst pos to work on/get to the carb

[@eddyquik]

Dude!!! This video . . . you should get a grammy!! My bike is idling perfectly now!! Your channel is . . . just wow! Thanks Mathew!

[@wyattrogers6008]

"take it for a ride" my bike doesnt even want to run

[@shadow1up]

Lmfao im on the same boat

[@Liamhultin]

real

[@Thepape209]

End up finding a solution ?

[@Casey5132]

Is there an O-ring that keeps the aftermarket fuel adjustment taught? On the appropriate adjustment out, about 1 or 1 3/4th turns out? It feels loose being that much out, feels like the vibrations of the engine will rattle it loose. Idk. Haven't ran it yet. Have a full carb rebuild kit

[@HTMR]

There is a little o ring for sealing, however the spring keep tension on threads to keep it from backing out.

[@ronaldwinzinger5612]

Trying to adjust a carb some built with with a rebuilt kit. My header is glowing n no idle..getting hot bad..its my first found stroke. Is it do to the air screw tan all the way in

[@_-Sparky-_306]

Bike won’t start off the kick but when I run start it I smell a lot of gas. Does turning the mix screw up up make it run lean or rich

[@admiralclawz8524]

I have a rmz 250 my fuel screw was adjusted to 2,25 turns and it only runs with choke and wont idle and the head pipe was glowing red

[@HTMR]

Sounds like you need to clean the carb.

[@charlesjohnston9067]

I have the same bike, mine leaks out of the overflow hose , what do you think causes that??

[@HTMR]

Dirty or worn float. You need to take it apart.

[@JenniferThornton-bb9vf]

I have a 4 stroke rugby 2022 scooter. Mine doesn't idle at all. I've tried idle screw and fuel on carberator . It just doesn't stay running when I stop at a light or stop sign. Any suggestions?

[@kimsands7989]

you lost audio at the start of setting, when you found it too lean.

[@takehow]

Yes, what's wrong - same 'muted n paused' effect when watching this on TV n tablet. .!??

[@HTMR]

That is why I reshot the video: kzbin.info/www/bejne/oYbaZWSpiraVirs

[@dans_rodsnkustoms]

Hey Mattew. I have a 2009 crf250r that is running rich. while riding feels great, I pull the plug out and its really black and suity. I've turned the fuel screw all the way in and it still idles perfect.

[@lmccoy010]

Hey I have a apollo 125 cc z220 max but the head pipe keep getting cherry red is that something to worry about because I dont want to die or it explode on me it actually look like it wants to in idle i dont look down while riding so I'm not sure if it's like that riding but after a few blocks it shuts down on me an i have to walk it home it wont start back till like a hour later like it over heats idk please help thanks

[@Cmoh30hollow]

My 2006 RMZ250 exhaust keeps going red should I get a new fuel screw or get new valves/jets ?

[@HTMR]

Make sure there are no vacuum leaks. No exhaust leaks. Fuel screw tuned properly? Does it glow while moving?

[@joemalofey7146]

Matt I have a 04 crf 250r seem to run a little lean in Michigan on 30 to 40 degree days what should I do

[@HTMR]

Joe, I'm in Chicago. Just wait for warmer weather...LOL. If your idle is lean, a 1/2 turn out on fuel screw is probably all it will take. If you are lean elsewhere, changing needle clip and main may be necessary.

[@joemalofey7146]

Can't wait till it gets warmer lol I want to ride but thank you for the advice I will try the 1/2 turn

[@TEST1887POWERHOUSE]

I have a 2002 yz426 it runs really good with the choke on but when I cut the choke off it cuts off every time. The guy I bought it from said it's been boarded out to a 5:25. Any reason why it will not run with the choke off hot or cold?

[@HTMR]

It's not getting enough fuel. Clogged or lean pilot jet.

[@TEST1887POWERHOUSE]

MatthewMCRepair Thanks man!!!! I'm going to have someone take the car down and clean it out. I'm looking at the Fuel and air mixture screw mine's is set on for I think that's too much I'm going to try and put it on 2 too 1/2 turn like you did. I'll let u know. Maybe I'll post a video of it

[@trevor4275]

Hey I have a 07 rmz 250 but want more performance out of carb. Any good carb rebuild kits that are good for racing !

[@suriyanarayananb7078]

Sir, if I turned the carb over tune, what will happen? .

[@taylorbwilcox]

I added a larger gas tank on my xr400 and when the tank is more then half full it leaks out of the overflow. Will adjusting the float hight stop it leaking? Thanks

[@HTMR]

The correct way is to replace the float needle, it might be worn. Checking float level to see if it is in spec will help also.

[@leemorley5610]

How do I find an air leak I’ve done a drop test and has 11% drop been told that’s normal thanks

[@dans_rodsnkustoms]

Hey Mattew. I have a 2009 crf250r that is running rich. while riding feels great, I pull the plug out and its really black and suity. I've turned the fuel screw all the way in and it still idles perfect. Also just wondering what the brass knob adjustment on the bottom of the carb does? thanks

[@HTMR]

Daniel Forbes What size is your pilot jet compared to stock? I think the knob you are referring to is the idle? Send me a pic here: www.howtomotorcyclerepair.com/contact/

[@dans_rodsnkustoms]

I installed a Dynojet kit and installed their DP JM 048

[@thomas73704]

Thanks I didn’t know the location of the screw till now thanks to you, turns out the screw was gone entirely, that explains why my bike keeps flooding and shutting off lol

[@R1cePudding]

Hey nice video, if fhese are out of sync could it cause idle rpm needle to wobble?

[@HTMR]

Single carb?

[@R1cePudding]

@@HTMR inline 4

[@bobczz3919]

I have a 2003 yz450f. If I am just cruising it seems to be missing, but if I give it gas it quits missing and takes of like a rocket. Would this be the air/fuel mixture not set right or something else? Love your videos.

[@bardinkurtis]

2007 yz 450f went from m 160-165, p 45-42, 5th clip, fuel screw out 2, leak jet 55-50 and its like it was before when all i did was adjust the fuel screw and now that i did everything right no change possibly a liitle worse and it pops when im lightly reving in nuetral on decel it seems to pop more when im lightly reving

[@diegovilla6417]

Hi, i recently bought a yamaha wr250f but the previous owner installed a Leo Vince exhaust and header. I feel that when you turn the throttle there is a delay on the response... does that have to do with the jetting of the carb?? Thanks

[@HTMR]

Diego, are you describing a bog when you quickly open the throttle while riding at a slow speed? If so, you need to address the accelerator pump circuit with a leak jet change and possibly the o-ring mod.

[@diegovilla6417]

MatthewMCRepair Yes it is exactly that. Thanks, I will take a look at it.

[@HTMR]

Diego Villa This video covers that circuit in detail: How-To: Jet a 4 Stroke MX Dirt Bike (Sample)

[@nationalforestriders]

my 02 yz426f bogs when I throttle ...would turning the carb adjustment... make that go away ?

[@HTMR]

Yes, fuel screw tuning and leak jet tuning will get rid of that bog.

[@nationalforestriders]

+MatthewMCRepair thank brotha .. i'ma rode this weekend. . I'll let you knoe appreciate it

[@rm25088]

yamaha Yz426f_yz250 also, yz426s are prone to bog because of the stupid accelerator pump. there's a mod you can do called the BK mod. lots involved. with carb off so you can see inside, give it gas. the pump will squirt fuel. the BK mod makes it so it only squirts fuel for about .5 seconds instead of the 1.5 seconds or whatever it is stock. I was going to do it but mine doesn't bog. only at idle if I slam the gas. riding it it isn't noticeable. maybe I got lucky and one of the owners before me did the mod already.

[@shad3654]

Now i have a 2012 YFZ 450 with a big gun exhaust and it seems to backfire could this be the issue i have been doing some research and it looks like i am running to lean should i use this method ?

[@kadanv8974]

Did you ever figure it out? My yz 250f is having the same issue.

[@rubenarutunianr1735]

I just bought a 2015 crf150rb and the guy put a fmf powercore 4 on it I asked him if he jetted it he said yea of course but I'm pretty sure he didn't know what he was talking about. and when I started it up next day with chock it started right up then I turned the choke off it idles for like 2 seconds then dies so I increased the idle and it started idling better then after the bike got warm it started Reving to high so I decreased the idle. Then I started it up today same thing happened what do you think the problem could be???

[@rustlerXL1]

I have an 06 crf450 and its really hard to start, and when it starts it crackles and pops and sometimes throws a blue flame out of the exhaust. I recently bought the bike so I have no idea what they had done to the carb, any thoughts on what the problem might be?

[@HTMR]

Start by checking for vacuum leaks at intake boot. Then make sure header pipe gasket is not leaking. Then try and adjust fuel screw like in this video. Check all those things and get back to me.

[@HTMR]

MatthewMCRepair One more thing, make sure the hot start plunger is clean and sealing properly.

[@brandonmedina8354]

Valves need to be adjusted forsure

[@thepoorprince3494]

@@brandonmedina8354 yah, a valve & stretched timing chain

[@techdroid6300]

I have a 2004 yz250f and I just put a new air filter in it and I bought the bike used and it wasn't adjusted so idk how many turns it needs to go. And in the book for the bike it doesn't tell you how many turns

[@HTMR]

Forget what the book says, that setting is lean. Do what the video says and you will see what you need to do.

[@techdroid6300]

MatthewMCRepair okay

[@LiveitLikeLogan]

Do you have a video on how to change a idle screw mine don't work in my 1999 yz400f so I'm assuming it's stripped and I need a new one.

[@TheAMG348]

Hey so I live in Washington I have a 2006 crf450 and I followed the steps and I also have a aftermarket screw. It idles perfect on low rpms with only about barley 1 turn out is that normal? Or what. I know with the stock screw I was running 2 out so please help

[@HTMR]

TheAMG348 The only change was the screw itself?

[@TheAMG348]

Yes. Stock spring and washer / o rings

[@HTMR]

TheAMG348 Sometimes I notice there is no RPM change when going from say 1 turn to 2 turns out. Is this the case? If not, maybe the aftermarket screw you bought has a different profile/tolerances....I dunno?

[@frankiiee_9875]

Hey Matthew, I have an 04 crf250r that is hard to start and idles funny, a little while back my fuel mixture screw fell out of my bike and put a new one in but not sure how much, I have checked the timing and valves, still nothing, can you get back to me please thanks?

[@HTMR]

If your fuel mixture screw fell out, I would make sure that the spring, washer, & o-ring was not lost either. If you are not sure how much you installed it, double check the setting per this video. The fuel screw has everything to do on how the bike starts and idles. If set improperly, it just won't start or run right. Do the procedure per the video and get back to me.

[@alroyal374]

Hi, maybe you will answer this please??! Got yamaha wr426. Start cold or hot from 1-2 kick. Idles fine,but then the engine gets hot the engine dies everytime you stop near the lights for example,you stop, it idles for a few seconds and just dies. Starts again with no problem. What it could be??

[@HTMR]

Do you have the idle set too low?

[@alroyal374]

MatthewMCRepair The idle is set around 1800-2000, recording to the tacho. Checked spark plug, nice brownish colour, at the moment i am doing valve clearances. Could it be jetting? I changed main jet from 165 to 170 and pilot jet from 42 to 45. Thanks

[@HTMR]

Al S OK, idle sounds high enough. After changing pilot, did you retune the fuel screw? Main jet has nothing to do with this issue.

[@alroyal374]

MatthewMCRepair Yes I did, probably hundred times now :) It is around 2 1/2 turns out now. Should i try to put 42 back in maybe?

[@alroyal374]

MatthewMCRepair what i noticed is that engine dies then temperature goes over 70 C degrees.

[@SuperMakster]

hey mat ive got a 04 yz 450 and i just cleaned out the carb on it bike only runs on choke off choke as long as i keep my hand on the throttle will this help any ??? Also been told that i should replace the spark plug because as long as i had it never have any suggestions???

[@SuperMakster]

not sure how long but i do have videos of my first rides on it they are really lame ones tho last time i rid it i road the shit out of it ended up issing off the neighbors lol

[@HTMR]

If you can hold the throttle and it will run, then just increase the idle speed??? Yes, change the spark plug if it has been a while.

[@SuperMakster]

i have tried that man doesnt fix it ive turned it up really fast slow then in between im gonna try to adjust the fuel screw this evening and try to start it i just always remember that those yz 450 are a bitch to kick start took 60 kicks just to get her to fire yesterday after i put the carb back on the bike

[@HTMR]

Sounds like good fuel screw and idle adjustment is all you need.

[@SuperMakster]

k found my prob tried the fuel screw adjustment didnt help at first but adjusted my throttle cable the fuel screw and idle its running tip top now thx man

[@lewiv7047]

to slow down Idle did you turn the screw in or out?

[@ExplorewithZac]

I just can not get my bike started :/ It will start and die sometimes.... sometimes it will only die when I pull the throttle.

[@73miguelangelo]

Hi I would like to ask you. I have a YZ400f only runs with a hot start on. First did it with the original carburetor. Now I installed a 2006 YZ450f carburetor and works better but still needs the hot start on.

[@HTMR]

Hot start adds air, so it sound like it wants to run leaner. Also, a leaner mix will raise the idle speed. Maybe your idle is set too low. In any case, try adjusting your fuel screw.

[@rungassamydonovan47]

hi matthew when you are unscrewing the fuel screw is it leaning or riching the mixture?

[@HTMR]

Lefty loosy or turning out richens the mixture. The screw meters fuel.

[@victorcarba726]

Nice video man really helps a lot. I'm having troubles with my bike reaching a top speed that it used to reach ( like it doesn't reach it no more) do you know what it might cause it ? Thanks

[@EliteGamer21]

losing compression maybe

[@illhaveanother4365]

Give it a red bull

[@blakevis5945]

Hi, I have a related problem with my 07 crf250 it was Revving real high so I adjusted the idle screw and did an idiot move of not remembering how far I turned it, now after 20 minutes of riding when I try and accelerate it will bog. I've tried to find find the previous spot on the idle screw but no matter what I try I can't stop it from bogging?

[@Aabbcczzxxcc]

hello. can you tell me please what type of hydraulic clutch on this bike ? I am using "easy pull" aftermarket lever, and it's working fine (much easer than stock), but i am going to try hydraulic too. thx ;)

[@HTMR]

Magura

[@Aabbcczzxxcc]

thank you.

[@AdventureWithDanan]

Hey MatthewMCRepair , I've got an 04 450f and I've got a couple of things going on, 1: It will not run without the choke on. Even when fully warmed up, the moment I take the choke off it dies. 2. My header glows red even after only a couple minutes of running it. I've heard that I need to richen up the Air/Fuel ratio.

[@HTMR]

+Danan Coleman In addition to the response above, which states to clean the pilot jet and all of the passages, I would check for vacuum leaks on the carb boot. Also, make sure there are no exhaust gasket leaks. I have a carb clean video & blog post here: www.howtomotorcyclerepair.com/4strokecarbclean/ Hope that helps!

[@AdventureWithDanan]

+rynousa Hey thanks! I didn't take it apart myself, but the shop that helped me cleaned the carb 3 times before it started running correctly, but it's running like a champ now!

[@AdventureWithDanan]

+MatthewMCRepair Thanks. It was just the carb blocked up. So now it runs great and starts on the 1st or 2nd kick.

[@HTMR]

+Danan Coleman Great! And sorry for the delayed response, sometimes YT does not alert me of comments.

[@AdventureWithDanan]

+MatthewMCRepair No worries.

[@ebarcoutdoors]

Please help: My 2008 rmz 250 is having sputtering/bogging issues in the mid-throttle area. I did mess with the fuel screw so that might be it but idk. It idles perfect and starts up first kick and anything 1/4 throttle or lower is perfect but as soon as I go to give it more throttle it starts to sputter and not give me any more power, but if I give it 3/4 to full throttle all the power comes at once and it pulls like it should. So basically sputters and won’t accelerate around 1/2 throttle range. Any help would be appreciated. Thanks. NOTE: It did run close to perfect before I touched the fuel screw but did sputter occasionally.

[@Edaddy58]

@barcafilms my 2008 kx250f does the same thing. It sputters and backfires a lot. Idk if it’s the jets or the fuel screw or something else

[@briangonzalez5360]

My bike is an 05 crf250r. Thing is it was sutting for 6 months. When it idles it dies so i got a bigger pilot and it seems to be working but it idles at very high revs... if i lower the revs though it will die. Any ideas? Also on 1st gear it accelerates a little on its own because its already has high rpm's. Any ideas? Thanks

[@HTMR]

Make sure you clean the carb. Take the fuel screw & pilot out and give the passage a good cleaning with carb clean. Make sure the hot start plunger is clean and proper slack in cable at lever. Next, check the air boot and header pipe for air/exhaust leaks. Laslty, tune the fuel screw and let me know what happens.

[@briangonzalez5360]

Thanks! Sorry about the grammatical errors, I was in a hurry haha. And yea I will let you know as soon as I do it! Thanks!! :)

[@Cabover362]

I have an 06 Rmz 250, i recently rebuilt the carb, put it back on and now the exhaust is glowing red out of the head when it runs choked cold, it dosent seem to get as hot when idleing but still gets a little red, could i have a problem with the hot start sticking causing a rich burn?

[@bbshooter36]

I have a 06 yz250f and it has a lexx mxe slip on exhaust and when I gun it almost instantly after letting it just idle it dies.. what main jet should I put in it?

[@HTMR]

+jesse Litchko Hi Jesse, sounds like your accelerator pump needs some tuning. I would recommend the o-ring mod and a smaller leak jet. Read this post and watch the video since it is same as your bike: www.howtomotorcyclerepair.com/jeta4stroke/

[@kadanv8974]

My yz 250f back fires, would that be too lean? And would this adjustment fix my issue?

[@HUNTERSCOLO]

My bike is running lean. If I turn the screw out 2 turns the bike idles very high and I have to begin backing it out until it idles right, however at this point this caused the bike to run lean and backfire badly. Any reccomendations? Maybe my hot start lever is stuck inside the carb? I honestly don't know where to go from here because when I finally have it idling correctly it's running very lean

[@HTMR]

If you turn the fuel screw out and the RPM's pick up, then you are heading in the right direction. What happens when you go 2.5 or 3 out? What are you doing to cause it to backfire?

[@harryhall4954]

I have an 07 rmz 450 if I hold it at rpm it bog a bit but if I open the throttle it's fine any ideas

[@mitchellwicklund8407]

Sounds like a clogged jet. How does it run with choke on?

[@HTMR]

Please clarify. If you hold the throttle steady it bogs?

[@joakimjensen8318]

ehh my bike is a 250 rm-z suzuki and it makes some "farts" is it something with the adjustment or? we havent tried to modify it yet so you have any suggestiosns? otherwise great vid ;)

[@HTMR]

When does it "fart". On decel?

[@joakimjensen8318]

MatthewMCRepair it farts when riding and when its in neutral...

[@HTMR]

Joakim Jensen Anyway you can post a video? First time I heard someone describe it as a fart noise...LOL.

[@joakimjensen8318]

not really :/ but can it possible be that it gets to much fuel? i mean that could cause the little pop from the exhaust? i mean when i start it and leave it for 1 min and gives gas some times there can get a little shot of fire out of the silencer? any idéas?

[@HTMR]

Joakim Jensen Oh ok I know what you are talking about. If you twist the throttle pretty fast it will pop correct? If so, your accelerator pump shot is lean or rich. Take the carb apart and find out what size leak jet is in there and compare to stock. Here is some good info: www.howtomotorcyclerepair.com/jeta4stroke/

[@Accidentalouttake]

hey im up for a little trouble, im going to change the camchain because it was in a bad way, but i cant get the stator cove off, it seems stuck( the screws) and i dont dare to take to much tork in case i ruin the bolt heads any tips?

[@paulcolson59]

I got a 2005 RMZ 250 how would you do that the Cubs adjusted at the settings I do not have the manual

[@HTMR]

Check out these jetting specs. They are for a KXF which is the same as your bike: www.howtomotorcyclerepair.com/how-to-kx250f-jetting-specs/

[@paulcolson59]

thanks

[@bardinkurtis]

put a pro circuit pipe on my bike went to pro circuit and got all the right jets they recomended on my bike and its still poppy when reving while im idileing any advice? been working on this for 3 days!!

[@HTMR]

Kurtis, what year make model and before/after jetting? List everything you changed. Keep in mind reving bike in nuetral standing still is not an accurate test. What do you mean by poppy? Decel pop? Does it bog when you flog it?

[@bardinkurtis]

MatthewMCRepair 2007 yz 450f went from m160-165, p45-42, 5th clip from top of needle, fuel screw out 2, leak jet 50-55 its popping when i lightly give it throttle and let go while in nuetral is when it seems like it pops the most its not extremely bad just not what i thought it wud be after making all those changes as far as that no lag or bog really once its warmed up and it rides good

[@HTMR]

kurtis bardin Kurtis, I see that a stock pilot is a 45 for your model. Why did you go leaner? What altitude/temp are you in? I typically have to run 1-2 sizes larger in pilot where I live (Chicago).

[@bardinkurtis]

MatthewMCRepair im in so cal its been about 65-75 lately and i dont no why for going leaner on my pilot just did what pro circuit told me but to be honest i havent went to actually ride it just did those changes reved it up few times and noticed the same poppage as b4

[@HTMR]

kurtis bardin Did you also set the fuel screw per PC's recommendation or per my video? I would go ride it and see what you think. Adjust fuel screw from 2 to 3 turns and see if symptoms improve. If they do, you are lean. Let me know what you find.

[@robertmcdaniel262]

What if u close it and it starts reving up as is get closer to closed

[@HTMR]

You need a leaner pilot jet.

[@robertmcdaniel262]

@MatthewMCRepair I'm at a 55 pilot jet with a 185 main jet checked for air leaks and got nothing

[@robertvincent905]

i recently bought a 2002 yamaha yzf r6 having starting problems. when it does start i would rev it up and it bogs down and stops. then trying to start again takes foreve rthen the same thing happens again and again. whats going on?

[@HTMR]

Start by checking for vacuum leaks: www.howtomotorcyclerepair.com/how-to-diagnose-motorcycle-vaccum-leaks/

[@robertvincent905]

no signs of vacumne leaks usd sea foam ran good but started to back fire and a slight blow by from crank case vent tube. still hard to start.

[@HTMR]

Robert, seafoam is not magic in a bottle. Anyway you can post a video of your issue?

[@robertvincent905]

sorry no video replaced battery, plugs, fuel filter and lines. getting spark, but need to use starting fluid to get started. runs then bogs down again, then hard to start. now it starts to backfire when trying to start it. ????!!

[@HTMR]

Sounds like carb is dirty.

[@andrewstevens7335]

what would cause my 2007 crf150r to idle to a normal idle and die and it is hard to start even when its been run for a while what is the problem please help

[@HTMR]

Andrew Stevens I'm not sure I follow. If your engine stalls when hot it is hard to start???

[@andrewstevens7335]

its hard to start hot or cold it stars when I push it off but that takes a few tries

[@HTMR]

Andrew Stevens I would start by looking at the fuel screw adjustment. If this is not adjusted properly, you can get symptoms as you describe. Start with that since it is easy to check, and let me know how many turns out you end up.

[@andrewstevens7335]

where is the adjust screw at on it i found the screw that adjusts the idle speed but that's it and the header pipe gets glowing red u can see it at night is this normal since it is a pro circuit t4 exhaust pipe and it is thin titanium

[@andrewstevens7335]

oh and when i try to kick it, it backfires one time every 10 to 15 kicks

[@ShannonHartnett-117]

I'm using a R&D flex jet on my keihin fcr 39mm flat/slant slide carburettor and it was the best $50 AU dollars I ever spent on my 2012 Suzuki DRZ-400E here in Australia they come already derestricted and run a 165 main jet and a 45 pilot and the 3x3 air box mod is already done on them

[@ProCro88]

Hello, first: nice vid: second: I have 03 yz450f. Idle is very strange. Sometimes it's very high, than reaturn to normal. TPS? Also, my header is glowing red? To lean? So I have to turn pilot jet counterclokwise? Thanks :)

[@HTMR]

+ProCro88 Sounds like you have a classic symptom of a lean hanging idle. Check for vacuum leaks, make sure carb is clean, then adjust the fuel screw.

[@ProCro88]

+MatthewMCRepair Hey, thanks for your response. I've just cleaned my carb, pilot screw 3 turns out, and set idle screw. Also checked TPS with multimeter and it's in tolerance (4,5kohm). For now everything looks good. Thanks man :)

[@HTMR]

+ProCro88 Ok, great. Keep in mind that at 3 turns out you are "borderline" and may need to step up to a richer pilot. I like to size my pilot jet so fuel screw falls at 2-2.5 turns out.

[@ProCro88]

+MatthewMCRepair Thanks, I will do so :)

[@FabioSilva-vs6ry]

BOA noite meu ktm sxf450 quando está mais quente fica a afogar tem alguma ideia da solução ?

[@YaBoyAlex2013]

I have a yz250f 06 that starts First kick when cold but after a couple laps when I turn my bike off and try to start it again it won't kick start at all I have to pop start it (Bump Start) in order for it to start! Any suggestions??

[@HTMR]

YaBoyAlex2013 Yes. Check the valves and fuel screw adjustment. Here is the valve adj video: www.howtomotorcyclerepair.com/yz250fvalveadjustment/ Matt

[@YaBoyAlex2013]

thanks helped a lot It turned out the previous owners had is turn 5-6 turns out when its only suppose to be 2-3

[@HTMR]

YaBoyAlex2013 My brother has the same bike and we installed a larger pilot jet, adj fuel screw, and set it at 2.5. I'm debating going up another size. If your bike is stock, I would highly recommend jetting it. Here is a vid: www.howtomotorcyclerepair.com/jeta4stroke/ Matt

[@mikem4371]

What do you do if it’s running too lean and when you give it throttle it revs high for a bit then settles down? It’s a brand new carb!

[@HTMR]

Adjust the screw out (richer). If you hit 2.5 turns out, jump up in pilot jet size.

[@thepoorprince3494]

@@HTMR Hi Matthew, is it normal to jump out 2-3 larger slow jet? I'm on 2.75 turn out 1 size larger and more that 3 turns if stock

[@HTMR]

@@thepoorprince3494 What year make model? Any modifications? How does it run with 1 larger at 2.75 out?

[@brianhallingrd2357]

I have a Honda CRF150R. i have a problem with my carb! When i have the choke on it, it runs good, i can't ride the bike without choke if is not warm. it must have choke in 5-10 min. and when it's warm and the choke is not on. and i give full throttle at low limit it's die. So is very hard to drive it because i have to work much on the throttle. I'm adjust the idle much but if i have it perfect it dies. so i need to have much idle or if i have my idle low i have to use my throttle little bit to it's not die. Thanks for the help :)

[@HTMR]

It wants more fuel. Carburetor is probably dirty or you have a vacuum leak.

[@brianhallingrd2357]

i can try to get more fuel to it. where is the fuel scrue?

[@HTMR]

Bottom front side of carb (engine side)

[@louisfennelly8876]

Hi. I have the same bike on the same year as this one. It backfires and pops hell of a lot. Any ideas. Thanks

[@HTMR]

Louis, you have to make sure the pilot jet is clean and fuel screw set right like in the video. Make sure you have no vacuum leaks and no exhaust leaks. Also make sure silencer packing is in good condition. What mods do you have? Pilot jet size? How many turns out on fuel screw?

[@ltburritoman248]

My 2008 crf250 idles fine but smoke comes out the back. I have a 185, 42 pilot, just cleaned and rebuilt carb...help

[@HTMR]

What color smoke? White, black, or blue?

[@ltburritoman248]

sorry for my late response and thanks for the response. The color was white, but it turns out I forgot to adjust the fuel screw after the change from 188 to a 185. Thanks for the response though!

[@janjakus3596]

What if I can’t even start a bike? I cleaned the carburetor two times, changed all seals in it, valve clearence and timing are set up correctly, new spark plug……and still can ‘t get it run

[@jacobmccain7364]

Awesome videos I see you have the hydraulic clutch set up. How do you like it?

[@HTMR]

Smooth like butta

[@thedani0937]

the head pipe of my 2011 yz250f gets cherry red very quickly, is that a lean or rich problem btw i have the slip on fmf 4.1 titanium carbon fiber pipe

[@HTMR]

Lean. Check for exhaust leaks/vaccum leaks.

[@antonispanonidis5773]

Happy new year!i have a ttr 250 and bike pops out a lot why?

[@HTMR]

Explain when it pops.

[@antonispanonidis5773]

MatthewMCRepair when i accelarate the bike and in deceleration it pops

[@HTMR]

I would check for vacuum leaks and clean the carb.

[@golferhack2309]

I have a 2012 KTM sxf everything is still stock. It starts just fine and idles just fine but the problem is when i turn the throttle a little bit and hit the gas it runs just fine but from a idle to hitting the throttle to higher RPMs it will die is it just a simple matter of opening of the fuel screw

[@HTMR]

Your bike is fuel injected so this video does not apply. Your issue is that you can stall the motor while on stand or nuetral while you whack the throttle? That aside, how does it behave when you ride it?

[@golferhack2309]

MatthewMCRepair My bike is not fuel injected there is a fuel injected version 12.5 but the orginal 2012's were still carburated it was the first year that Dungy came to the team. And that is correct while on the stand and while in neutral. it has stalled on me when i was messing around rolling over a small jump and i whacked the throttle and it did the same thing. So what i'm thinking that it could be the fuel screw or bad gas?

[@HTMR]

2012 KTM SXF OK, sorry about that, didn't know it was carbed. How many turns out are you on fuel screw when you perform the procedure in this video? Also, read this: www.howtomotorcyclerepair.com/jeta4stroke/ Your problem is probably due to a lean accelerator pump shot. Read the link above and let me know if you have any questions.

[@rideblue1456]

Hi I have a yz250 what's the purpose of a the throttle stop screw ?

[@HTMR]

If you have a YZ250, then that carb is completely different. Disregard this video.

[@AzTechGFX]

Hi bro my bike splutters on Rev, will adjusting correctly fix it? My fuel screw has fallen out forever how long so would this be the cause?

[@HTMR]

Buy a new one: amzn.to/1OM0eD1

[@AzTechGFX]

MatthewMCRepair is there no other way and do you think it will help my splutter if I adjust my carb correctly?

[@HTMR]

Not sure, however you need to have a fuel screw installed so I would start there first.

[@KayGmacK3232]

I have a 05 yz450.... was running fine but a little high rpm.... I turned the idle knob and it stalled.... when it was off I teied turning it back to whre it was in the first place..but cant get it started..... is there a spot that the knob should be that I can find when its off?

[@HTMR]

These bikes need to idle at 1800 or so. Screw the know in 1/2 to full turn and see if it will start.

[@Julsmathieu]

is it the further in it is the less fuel?

[@HTMR]

Yes

[@ItsKanches]

Hey there, so I have a problem with my 07 KX 250f, It has a pretty bad backfire problem when it is going down from high rpms, and it it even does it quite a bit when it is just over idle speed. I know some backfires are normal, but mine does it 2-3 times per second until you are down to idle speed or hit the gas. It hasnt really affected the performance much, but I dont know, just seems a bit inconvenient. Do you know any good ways to reduce those?

[@HTMR]

catman377 First off, make sure there are no exhaust leaks at head pipe and muffler connections. Also, make sure silencer packing is good. Next, make sure there are no vacuum leaks around carb boot. Make sure hot start plunger is clean, sealing, and cable is properly adjusted. Finally, adjust the fuel screw per video and size pilot jet so screw falls 2 turns out. I had to run a pilot jet 2 sizes larger for this bike in my climate (Chicago). Hope that helps.

[@rctodayukshaun4817]

Hope someone can help I have a 08 yz450f it was running good till the fuel screw fell out I bought a genuine replacement turned 2 turns out the bike will not start it sometimes fires but that's it valve clearances are well in spec new plug good compression but nothing

[@HTMR]

Did you make sure the washer and oring where not stuck in the body? Could be possible that you doubled it all up.

[@rctodayukshaun4817]

@@HTMR Really appreciate the reply its 100% only got the one o ring and one washer and spring its really hard to get started once it does start front pipe glows instantly and runs like a pig like its really lean its 45 pilot 170 main

[@HTMR]

@@rctodayukshaun4817 So did it run fine before your screw fell out?

[@rctodayukshaun4817]

@@HTMR yeah it ran well now I'm struggling to get it to start to try setting the fuel screw

[@HTMR]

@@rctodayukshaun4817 Try opening the screw 1/2 to 1 turn more.

[@dirtbikeevent7162]

any problems with your hydraulic clutch?

[@HTMR]

Not my bike so I can't comment. It has never been in for repair however.

[@MrHandoverfist]

on mine , the head broke off.. where it hooks onto the lever at the engine. left me why out with no clutch..never bought another..and it was not any better feel then a good cable.

[@noahpearson6824]

Hi I have a yz250f it won't seem to start cold or hot I have installed a new spark plug new fuel line new air filter after a long time it will eventually start and ride anyone know what I can do

[@HTMR]

Adjust the fuel screw (assuming the carb is clean and valves are adjusted)

[@rm25088]

MatthewMCRepair that would sure help. I know on my yz426f there is a special procedure on starting it. you have to kick it over until you feel top dead center. kick down a few inches and bring the kick starter back up, then give it one strong kick. my bike usually starts first kick. and they say 426s are hard to start. bull crap. I have this same screw and i think I have it set right. now I'm second guessing myself. I'll retry on Monday on my day off and see if I can get it running any better than it already is. I don't know how much compression a 250 has but try my method on starting it. my old rm250 was real easy to start.

[@lucascolarossi21]

i have an 04 kx250f and i just put clean jets in and it doesn't want to start and it pops and back fires and will die if your not on the gas. anybody help me please?

[@HTMR]

Did you replace the pilot jet? Did you remove the fuel screw and clean the pilot/idle passages in the carb body? Did you check for vacuum leaks? Hot start working properly?

[@bignickbaker3340]

my 01 wr250 hesitates for a couple seconds then picks up speed can anyone help me and tell me the problem?

[@DWad3MIA]

+Nicholas Baker I have a similar problem with my crf450r

[@bignickbaker3340]

+Call_M3_Mr_T do u know what the problem is?

[@DWad3MIA]

Nicholas Baker No.. I was hoping someone would respond to you.. If you find out your problem let know and I will do the same..

[@bignickbaker3340]

+Call_M3_Mr_T will do

[@ES-rk1pj]

+Call_M3_Mr_T what year crf450r do you have? seems like my 06 crf450r has a bit of hesitation now. when i first got it it seemed to have wicked fast throttle response. It did sit for a while, and i cleaned the carb although it still seems to lag.

[@jdmkid4617]

My bike was top end rebuilt and now its running lean what do i do its a 2002 yamaha yz250f

[@HTMR]

How do you know it is running lean?

[@jdmkid4617]

@@HTMR I havent started it taking word from previous owner

[@HTMR]

@@jdmkid4617 Don't take previous owners word. Don't assume.

[@jdmkid4617]

@@HTMR we took it into a shop and he said it sounds good and is running lean and I get what ur saying

[@HTMR]

@@jdmkid4617 Well, I think you should tear the carb apart and then email me all the jetting specs that you have. I have a good jetting setup for that model.

[@1firejosh]

Why did you increase the idle in the end to 1900 rpm's?

[@sledmaster89]

where did you get that airbox?

[@HTMR]

I have no idea sorry.

[@IVJmes]

How do you make sure your screw doesn't fully fall out

[@HTMR]

That is the purpose of the spring, to keep pressure on it so it doesn't back out. I wouldn't go past 2.5-3 turns out, otherwise it may fall out.

[@henrygoley3842]

which way is lener and which way is richer

[@TRX450RVlogger]

Loosening it is Richening it up. Tightening it Leans it out.

[@HTMR]

TRX VLOGGER described it right. Keep in mind screw is upside down.

[@TRX450RVlogger]

Good Point.

[@MxMax-iu9dt]

My bike, even when I adjusted the fuel screw sometimes when I’m going fast to much fuel goes into the engine and bogs out.

[@HTMR]

How do you know it is too much fuel. Could be a lean bog.

[@MxMax-iu9dt]

MatthewMCRepair I do like full throttle and then it starts bogging, but when I go slow it’s fine

[@HTMR]

@@MxMax-iu9dt What year make model?

[@MxMax-iu9dt]

MatthewMCRepair 2012 yz250f

[@HTMR]

@@MxMax-iu9dt kzbin.info/www/bejne/boSxeKBpqciEjLs

[@yeahwerepthesamesmartech7113]

my 02 crf450r started as nice as yours when cold 3-4kicks max... then i messed with that idle screw. i think i had it way to high because my bike would only bump start and to be honest now hearing what u say is about 1800rpm i prob had my bike revving at 5 or 6000rpm.. shameful... i need data plan and i would of had it figured out

[@thepoorprince3494]

CRF recommend 1700 +-100

[@hasanacer_]

my problem when overturned not working

[@kylezelazny2008]

The bike ran WAYYYY better after getting this set properly..Just bring your bike to Matt and have him get it squared away, especially if you don't know what your doing!

[@HTMR]

I wouldn't say so. At least it is easily accessible. I love doing this to an inline 4 where a $80 90° screwdriver is needed.

[@oscararnesen699]

I had a problem with my kx250f. Its like shooting/farting when gives a little gas, but no problem at almost full throttle. I just got a new airfilter and new Engine oil, and i havent heard it yet, but do you have any clue what i could do to fix it? Would help me alot! KX250f 2007

[@allanknight1910]

You want to let he bike idle for a while after each slight adjustment the bike won’t react straight away

[@christcrucified6385]

Man I just crank the idle up and then turn the screw in until it about dies and then slowly turn it out until the idle shoots up again. That has seemed to work perfectly for me and it takes a whole lot less trial and error.

[@HTMR]

Sure that will work, however you don't want to adjust idle too high since you will be off the idle circuit.

[@christcrucified6385]

Hmmm

[@HTMR]

JD Yamaha The more the throttle is opened, it will start to transition to other circuit. The idle would have to pretty damn high though.

[@christcrucified6385]

I see what you are saying. Either way will work I guess. I never thought of getting to the next circuit. I tried your way today and it works as well. I just don't get the exact spot that I do with the way I normally do it. I have to kind of find the middle between the two places it starts to die.

[@christcrucified6385]

Thanks for helping people by the way!

[@dedro01]

good video. thanks. very important that the engine have very good idle.

[@techdroid6300]

My clutch is also really stiff

[@HTMR]

kzbin.info/www/bejne/oJfPi32LZ9h4jKs

[@richardhyde6418]

Thanks for posting. Makes sense for a new stroker owner.

[@ИльяДудин-з9я]

Guys can someone come across such a problem Kawasaki KX250f, HELP PLEASE !!! In general, once again he started the moto to ride through the terrain, warmed up a bit and drove, literally a hundred or so meters later, he began to seem to be choking, dips, shooting. He stopped drowned, started progazovat everything seems to be ok, but the speed control at medium speeds all repeated and so constantly. Generally thought on the carb. Removed the carb washed, cleared everything seems to be as normal, all in good condition. Collected nothing has changed. The brightest manifestations of this garbage when you go on 3 or 4 gears and you start to slowly unscrew the throttle and here at about the very middle the shooting starts, dips,but if you open the throttle strongly, it is as if he progazoval and breaks through and begins to throw at high speeds normally. It turns out at low revs it works stably, at high revs it also works stably, but at medium revs it soars He put on the overhaul repair, made hon celindra replaced the piston, timing chain, new valves. Everything seemed to be good today, I worked at idle, I tried to drive everything, but then decided to add a little more gas and the same garbage, dips, claps and twitching began again !!! The guys just hair on my head will soon vomit !!!))) What is happening to him? !!!

[@HTMR]

It is really difficult to understand this translated text.

[@ИльяДудин-з9я]

Sorry if something is wrong or incomprehensibly written, I used a translator, and he translates as he wants))

[@ronaldwinzinger5612]

Head pipe glows cherry red n catches fire