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

[@raffistepanian3634]

Hity carb, just replaced PD19J with PD18j, #34 pilot, #75 main. It is 1-1/4 +_ 1/8 (that 1/8 is like a fine tuner/turner). Redid the float hang, pried it slightly up - - the float is parallel. Throttle response and release, idle return is key on. It never felt this responsive, strong with dead on return to idle RPM. My setting, with your demo, brought my engine sound, crisp, like your baby. The instruction was dead on. I’m on a 50cc. Really cool! Thanks!

[@NoBody-ol3jr]

Thanks so much man, my bike would run to hot and never want to start. Now I turned it to 2 and it’s less hot has more power and starts up

[@EAC918]

Thanks Matthew great instructional video, I’ll be watching. I try to do all my own work on my bike YZ250f, these types of videos are very helpful. I like how your to the point and give the viewer what they need, minimal chatter.

[@michaelarmendariz1572]

Did it work after u adjusted the screw ?

[@SoFlyOfficial]

I'm buying a used bike tomorrow and I don't know anything about maintanance on the dirt bike yet but it is a 125cc 4 stroke (Japanese brand). I would like some tips on what go adjust or change when I get it

[@HTMR]

125cc what? Best thing to do is get a service manual and read the maintenance section. It will explain what you need to do.

[@akbarhussain1767]

Hi Matthew, thank you for that tutorial with the fuel screen,I will try that with my Yamaha sr 125cc carburetor 1999,I've been having idling problems, my fuel screw "is" fully seated in,therefore, I need to turn it out 2 turns & listen to the rpms, hopefully, should become higher,thank you friend & your engine sounds Awesome, the way your power drops immediately after throttle is the works ,thanks again Matthew 🙂🙂🙂

[@transzilla7577]

Best explanation to this 4 stroke carb tuning. Great video thank you.

[@Sincethe80sGaming]

Great video, could you do a Honda Navi is a 4 stroke engine too!

[@alberto-cg7ox]

Thanks for the vid, One question, if the screw Is all screw in, (leaning) the bike must stop?

[@brianhansen6906]

Great information and well presented. I just got a used crf450x that smells like it runs rich and even runs like it runs rich and even when the engine is cold it starts better with the hot start lever pulled lol. I’ll be trying just what you did tomorrow. I’m guessing I may need to go to a smaller pilot as rich as it seems, but we’ll see.

[@CamoPajamies]

I’m going to visit your website to see where you mentioned if popping or rumbling on deceleration , and or if a backfire snap after full throttle then let off snap, seems somewhat healthy or not? And side note how important is backpressure(a metal screen on end exhaust is just for dirt or really important)? U r a genius

[@jessiezarbb7805]

Great video just bought a bike an it wouldn’t start , did this and she fired right up easy an to the point 🤟

[@ridinfaster]

Thanks, Exactly what I needed to solve my throttle hanging up on my freshly rebuild 250F

[@jakelewis1168]

Same

[@rileyduff6604]

did u just turn the fuel screw and it fixed it ?

[@ridinfaster]

@@rileyduff6604 yes. I bought an aftermarket fuel screw, installed it and followed his instructions. problem solved and I learned something.

[@rileyduff6604]

Brian Rose cheers bro yeah i fixed mine but i still have stock fuel screw was so hard but i got it

[@richardtschida2321]

Man I can't tell you how much you have helped me with my fcr39mm! Dude you are my fcr mx guru thanks for the information. I am doing a drz400 swap.....so much help again thanks!!

[@aaronr7389]

Excellent explanation, thank you! Ran out of daylight today. My fcr idles excellent but I have a hanging idle when i blip the throttle. When I turned AF screw all the way in the bike didn't die. Maybe a float or cable issue?

[@HTMR]

Year make model? Stock pilot jet? Any mods?

[@aaronr7389]

@@HTMR 2006 yfz450 (ATV) bill balance edition 48 pilot jet, 165 main jet, K&N filter, EHS lid, heads P/P, FCR is bored. cam mod , AC pump mod (zip)

[@MAPEXable]

I'm gonna try it when i get home today...hopefully it will help with the bike not wanting to idle

[@l6st.663]

My quad seemed to get hot really fast after new exhaust and better filter im guessing it’s funning to lean ? To much air not enough gas ?

[@mariosalcido1490]

Dude my kx250f runs perfect now thanks the fuel screws was all the way up

[@hiimdias115]

My carb from my 08 yz450 i turned it all the way in and the bike didnt died.. I cant really notice any Diference when ajusting the screw. And on 1/4 trottle She hesitates thanks 4 help

[@seatime674]

On my '05 WR 450 i have it running perfect but alot of popping on Decel, what can I adjust.. Ty..

[@earvizu5648]

I have a 2014 yz450f with a rebuilt and and had a filled up to the top with antifreeze but for sum reason the bike gets imidietly hot but I haven’t been able to ride because I don’t have a back tire right now so I just leave it idleing

[@ryanstephens2157]

My 05 Kx250f has been backfiring like crazy when letting off the gas or decelerating the least little bit. Any ideas? It was revving and returning to idle perfectly and then bam, all of a sudden.

[@CaseyFleetMedia]

My xr650l runs good at about 3 turns out... Is that ok

[@HTMR]

Yes

[@CaseyFleetMedia]

@@HTMR thanks bro... I did go ahead and order a 55 pilot jet

[@Nonplused]

Nice! Most of the recent carbs, especially the ones with a plug over the set screw, come set too lean for emissions reasons.

[@speedymarc]

what about the idle screw? my knew pit bike 125cc 4t only starts when the choke is open even when it's hot, I've been testing the screws and I think I've messed up the mixture, it runs fine anyway, it doesn't die at half throttle and it doesn't lock up at full throttle but I have to have the choke open.

[@jbraz8]

This is great man. So easy to follow. I've got a custom fuel screw on the way and now I'm quite confident in what's got to be done. Cheers bro thanx!! Jamie

[@HTMR]

Cool. Keep me posted on outcome.

[@jbraz8]

MatthewMCRepair The screw is in place! Couldn't believe I had to dam near completely disassemble the whole bike to get the carb out though lol.. after rewatching this video I definitely have to adjust my screw though, to many people telling me my idle was too high but after hearing your bikes idle, I'm going to spead it up. I'm riding a 2008 crf450x

[@HTMR]

Yeah, it takes some effort to get to these carbs.

[@brianirwin9072]

Matt I got problem with my 07 rmz250 got to idle but as soon you touch the gas shuts off was a pain to start but now got it to idle has 270 kit stage 3 procircuit kit from cams to titanium valves n exhaust ported n polished whole works like it’s starving for gas carburetor been rebuilt any points on it thanks

[@paullussier9349]

2021 Rmz 450 revs too high during cold start when choked?

[@Rootbeertree]

I love the videos they are very informative. I have a smooth running idle but when I blip the throttle it seems like it hangs rather than going down to idle. And suggestions?

[@HTMR]

You have a lean hanging idle. Adjust fuel screw richer.

[@danielalexandresilva2913]

So if my rpm drops slowly it's rich? great video, helped me a lot. regrats from brazil

[@HTMR]

After a blip of throttle yes.

[@dantsy6397]

@@HTMR 1:35 but you said if rpms hang you gotta richen it up. So is it rich or lean if the rpms hang?

[@HTMR]

@@dantsy6397 hanging rpm is lean

[@fuegodonkarim1195]

Can you Help me ? I have a Kawasaki KX450F from 2006, but they did some changes to legalize it in Switzerland (changes are not professionel). Now i try to rebuild it to the original cross. You hava a Video or an advice for the electronics ? Thank you

[@bigironjakesd619]

My 2004 honda crf250x with a fcr carburetor has a 155 pilot and 42 main jet and the fuel screw and needle clip in position #5

[@ericlizada1570]

How about the air idle mix how many turns min. And max?

[@ronanrogers4127]

FYI you can fit the R&D Racing Flex Jet to the FCR39 even though they say it only fits the MX version. The flex jet is in a better position and easier to adjust. I just used a small rats tail file to remove a little material from the tunnel that the screw runs through, it’s very easy. Some people drill the hole wider, but the interference is not concentric so drilling isn’t required and is a little more risk.

[@blakemh]

So this is good info but what keeps that screw from falling out? Cause mine is loose and rattled out and gone forever , almost prefer factory one so that it doesn’t fall out, or was mine old and warm out?

[@HTMR]

There is a spring to keep tension on threads.

[@davidmadison8973]

Need help, I think I have a 49cc 4 stroke Motor. How do I connect and idle the carburator?

[@bryanmacneil2068]

Im having a problem with my 07 ktm xcf250. It runns on the choke but without the choke it will die when i use the throttle. Jets are clean and accelerator diafram is good. And idea what it mite be. Thank you.

[@FabioSilva-vs6ry]

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

[@j.lozada_clout2725]

hey man, my bike will bump start but not kick start. any suggestions? 04 kx250f

[@MadiliaSarwary]

On which carb must i start if have 2 carbs? Suzuki intruder vs 800 1994

[@TheBigsteww]

AWESOME video... I'm an old guy, and new to this.... Mine has #'s 1-4 on it, so one "whole turn" is 1 ALL THE WAY AROUND back to 1 correct? Thank you!

[@HTMR]

Yes that is considered one turn

[@bigstew9724]

@@HTMR damn 5year old video, STILL helping others. Appreciate it. Have a good one.

[@TN_HondaDad]

How can you tell it's seated when you turn it it? Is there resistance? I don't want to turn my in too much as damage the thin tip needle? Thanks for the video -helps understand how to tune and more importantly which direction to turn for rich/lean.

[@HTMR]

Use light finger torque and seat it until it stops. Use very little force and you will be OK.

[@c4r5on88]

I have a kxf250 and the idle screw the black plastic one won't turn. I can move it a tiny bit and it just bounces back. Do these jam for any reason? I ask because I need to adjust it as my bike won't stay running when ticking over :(

[@dun85r95]

Good job that was probably the best video on that only thing you could have done maybe is show how to use a volt meter for guys that don’t have RPM screens

[@HTMR]

Just tune by ear then.

[@jamesharrison7326]

is the carburetor Same as pz30b carburetor with acceleration pump and slide

[@cqrter]

so when ur talking abt the fuel screw is out from something, r u talking abt out from all the way in?

[@dariangerardo2]

What does it mean when i blip my throttle and my bike dies? Great video by the way!

[@keithbyrd3042]

Bogging out or a misfire

[@jakepennington8507]

What of i have the hanging revs coming back to idle but can allso turn fs on all the way and it doesmt die? Also have a bog on snap throttle while on stand

[@tieNagle]

Awesome and to the point, thanks! I found out my hot start was corroded in the open position and causing a similar popping..

[@admiralclawz8524]

What is a hot start? My rmz 250 pops a little But when i start it the pipe gets red

[@nexxpe]

got a kawa 2011 250f there comming fuel to the karburator but not feeding it to the engine whys that?

[@phlillipurface]

Very helpful video but you said in the video that turning the fuel idle adjustment counter clockwise lowers it however the manual says different, wad that a typo or is the manual wrong?

[@HTMR]

Remember the fuel screw is upside down. Lefty loosey is richer.

[@dgmenace73]

Thanks for your video.....can you tell me what would cause one, after adjusting to hang the idle then by itself start stumbling a really low idle then again, change to a hanging fast idle without touching the screw? Hopefully I explained good enough....it just seems to have a mind of its own...lol. thanks in advance.

[@HTMR]

Did you check for vacuum leaks?

[@dgmenace73]

@HTMR I did...Originally it had a cracked intake boot so I purchased a new one. When spraying the intake boot now with carb cleaner, nothing changes like it did on the cracked intake boot. I think the o-ring on the pilot jet is probably shot allowing it to suck air through a bad o-ring? I just don't know what else would cause it to change so drastically without touching anything.

[@HTMR]

@@dgmenace73 Year make model? What is stock and current pilot jet size? Fuel screw setting?

[@dgmenace73]

@HTMR I ordered a stock pilot jet and its running like a charm now. Thanks

Hi Sir! thanks for share! Excuse my wrong english please! For pilot screw adjustement the higger rpm means stoich AFR? That little partial turn enrichement way that does not rise the rpm, can be cosider that rich range from 14,0:1~12,5:1 before rpm drops? or what AFR range would means? About main jetting, propper or safe combustion, AFR stoich or rich safe range and spark plug reading, are plug chop method the best way to look how many carbon deposits spark plug shows? O² sensor is not easy tool here... how many combustion time a spark plug need to show enough carbon deposits for every jet tested? I tested 5 jet numbers up from stock and not visible ring carbon deposits at insulator base after cut the thread body. thanks a lot Sir!

[@releasedmike]

Is it the same for the twin air

[@WrenchingRajch]

I’ve got an 06 wr450. It has a problem with choke. Cold starts are easier with the choke off as for with it on, the bike just dies. warm starts are fine. In general, it just seems like it could run smoother. Looking for any advise before i get around to setting the fuel screw

[@HTMR]

That happens when fuel screw and/or pilot jet is too rich.

[@matrixx29]

hey man, great vids. I have a 2009 RMZ 250f that all of the sudden started to rev super high in the air after i hit a jump. NOT GOOD.. the bike rips when i'm riding and sometimes will hang after i let off the throttle going into a corner. all i need to do is blip the throttle real quick and it typically idles right down. very odd. same thing in the air.. if i blip the throttle, the revs come back down. too much work though... i need to fix this. So i put all new jets and seals hoping it just needed a rebuild.. but same thing only now it doesn't want to cruise without sputtering. under load, no problem. she'll scream.. but it still hangs and now won't just cruise down the road without sputtering? fuel screw adjustment too lean?

[@adamVLA]

Sa.e problem on my 07 rmz 250 throttle hanging up too long

[@bustervetier5652]

what if it want ideal and cuts out when you push choke in and it back fireing lots

[@vogs2]

I'm having this same problem with my bike right now and can't figure it out"

[@kariholma3850]

@@vogs2 I had to keep choke pulled out even when engine was warm, and didn't start easily. Also backfiring. Opening the fuel screw a bit for richer mix solved all these problems.

[@somerspeat4912]

Would this fix a bike that feels like it’s sputtering and backfiring?

[@jbtwo1733]

Great vid! 2010 YZ250F. My set fuel screw seems to come loose when I’m riding which then leads to the bike cutting off. Can I replace it or does it need some type of thread lock to hold it in place ?

[@HTMR]

How many turns out are you?

[@Thetowguy77]

Do you do it with choke in or out?

[@jonathaneriksson5827]

ive got an issue with my yz450f, when i press choke back in bike dies, if i throttle and push it in, it's like gas exploding in the exhaust could it be something going on my valves or the fuel, sorry for asking, im new to 4-Stroke :)

[@propedope9594]

Your videos are very helpful! I’m doing a FCR on my LTZ400 would the adjustments be the same for my quad? Fcr is from a yfz450 .

[@HTMR]

Yes, this applies for all FCR carbs.

[@zachariahwoodside4048]

I need some help, I bought an 04 suzuki rmz 250 had a bunch of work done to it by previous owner like big bore 290cc and rejetted carb but idk the size.. my issue is it's a major pain to get started have to kick it several times but once it's running it runs great. How do I make it easier to start tho?

[@HTMR]

Start by tuning the fuel screw.

[@lemontebrown566]

Can this cause ticking noise ? Other then valve or tensioner

[@CoralReefkid]

Hey Matt, say someone messed with my bike and it’s not starting at all. Will tuning it this way be impossible without starting it? Am I wasting energy adjusting and kicking?

[@therationalmillennial8016]

Matt, great video. how would I go about draining the fuel on my 06 kx250f?

[@HTMR]

Why drain it?? Loosen the 17mm bowl nut.

[@Zachcamaj]

I have another question. My 2002 crf450r owners manual says stock pilot jet is a 45 and the main jet is a 175. I pulled the jet out thats at the bottom of the carb. It's labeled 45, but everywhere I'm looking it says the jet I pulled is the main jet, so where is the confusion

[@HTMR]

The 6mm hex is the main jet.

[@briankeene3577]

Thanks a lot matt, I appreciate it. I'm not to computer oriented and I just stumbled on your comment accidentally. I'm trying to get up to date here in 2017 haha

[@jayp7043]

I have an FCR-MX 41 installed on a quad that was originally injected. If I start from 2 turns out and tighten slowly (lean) the idle increases a lot right up until fully seated. As if to suggest more screw turning could further increase the idle. If I start at 2 turns and open the screw (rich) it slows down till it dies at around 3 turns. I believe that means my pilot jet is too big right? I think I have a 45 in there now. I'm thinking about going to a 42. Thanks

[@HTMR]

Yes, maybe even a 40.

[@jayp7043]

@@HTMR Thanks Matthew. I had a 42 in there so going to try a 40 now. Of course I lost the spring on the fuel screw so I can't even try it till next week. arg!

[@HTMR]

@@jayp7043 Try a spring from a pen for the time being.

[@jayp7043]

@@HTMR that is a great idea. I just got this post today and somehow the new fuel screws came yesterday. Thanks!

[@comedyalex3198]

My kx450f 07 won’t start there’s Fuel in and the choke is on can you please fix this adjustment

[@nerfomkiwhat]

when i turn my screw fully in the bike doesnt die, what could this mean?

[@michaelhealy81]

If in doubt rule it out. Runs better but still popping on decel. I care not as the power is smooth. Great info, thanks !

[@Dale-yv1gq]

Hi I have a trx 450er hinson race parts when I start on choke idle the header glows red is that normal or would this idea help the situation thanks

[@racingdreamz8021]

I have a 09 Yz450f with a full fmf exhaust, It backfires during deceleration so do I turn the screw more rich or more lean?

[@HTMR]

Richer. I usually install one size larger pilot jet also.

[@racingdreamz8021]

@@HTMR Thanks bro

[@hyrumbeck2739]

My 2004 yz450f is running best at 1.5 turns out. I had to mess with the idle adjust also, but it's running like a top now. It was still running though when I screwed it all the way in. What does that mean? My pilot jet is too big or too small? Don't know how much it matters but I live at 4500 feet and regularly ride at 8,000-10,000 feet.

[@HTMR]

Pilot jet too rich.

[@didnthurt4077]

Good video Tutorial! One question tho, how many turns out for the idle screw when starting from scratch or is a good starting point?

[@HTMR]

I don't know off the top of my head. Just screw it in to see a bit of light past the slide.

[@gennaroscotti3289]

ok thank you , The reason I asked is because there is no data from Yoshimura. I called them also,they said no allowed to give that info.Would you be able to recommend starting numbers?

[@HTMR]

+Gennaro Scotti I don't sorry. Visit FMF or Pro Circuit site to view their jetting database. Or just make it easy on yourself and buy a jet kit. Here is a JD jet kit: amzn.to/1ODJyN6

[@neocorp9194]

Will this help me on starting my bike hot? Because its a nightmare to start hot? But 2nd kick cold

[@HTMR]

It can for sure.

[@RuFLeSsgaming]

Quick question. So i have a 2004 honda crf250r and it wont start now i have to build compression on it and then it just backfires and sometimes even almost starts i also noticed i have a fuel line with a significant leak on it do you have any thoughts on what this issue could be ?

[@HTMR]

First, take care of the fuel leak. I don't know what the problem is but I'm willing to bet the carb is dirty and improperly tuned (fuel screw).

[@crunch_amp9282]

I have a question I took my 2007 KLX 300r to my dealership to have the valves shimmed he shamed the intake valves and exhaust valves were fine it kicks on one start now to start up but on deceleration probably from 3 to 4,000 or more RPMs when decelerating it gives a little pop towards the end of the decelerating possibly because files are out and need to be seated a little bit more for us running time it was also 42° out and I've never ran the bike and that cold temperatures to know if it's still gives a little pop on deceleration or is it air fuel mixture screw

[@livingthedream4882]

Quick question mate...I got a 4 stroke 250..its new when I pull the throttle back fast it cuts out do I need to screw the screw in or out on carb

[@HTMR]

Lean fuel screw/pilot jet/ and acc pump shot. I have videos on all these items. What year make model?

[@robertandri5919]

Why is my bike back fire-ing just adjusted the valves is my pilot jet too small or too big or is my needle clip to high or too low my fuel screw is set at twoo turns out what should I do??

[@sheffcityjl1119]

Your idle screw is the fuel screw what you on about? How can you have an idle screw and a fuel screw? You have an idle/fuel screw and an air screw

[@kingd4zer]

I have a yz450F runs good but back fires when u decelerate. Could this be the problem or could it one of the jets? The valves are good I checked them as well.

[@HTMR]

Could be lean, or exhaust leak, or blown out muff packing.

[@kingd4zer]

MatthewMCRepair thanks I appreciate it I’m gonna check my spark plug after I ride it

[@thistledewoutdoors3331]

I went to go se my 2004 kx250f & i pressure washed it super good - looks brand new !!! But,,, the damn thing started to run like dook..... (Pressure washer might have turned fuel screw) idk but ,,, it started running hot & melted the airbox & spit out coolant for the first time ive ever seem that happen since ive owned it new..... I could not figure it out - this video nailed it & my bike idles , revs down & runs like before.... Slight bog at initial throttle but managable

[@HTMR]

I have vids to clear the bog.

[@xxgamingbossxx40]

Hey my 04 crf450r doesn’t wanna idle when I set the carb to it’s settings (2 an a half turns out on idle screw an fuel mixture an 2 turns out it’ll rev to the sky but it starts very easy but when I get the idle to be low but I have to give it gas so it won’t die it’ll be very hard to start

[@xxgamingbossxx40]

Andy idea what it is?

[@philibertdepange4692]

Hey, I have a kx250f from 2007, and I can't find the fuel screw and the idle adjustment, it's not the same carburator. How can I fix my fuel screw? Because I always have to throttle, otherwise the bike stops and I'd like to fix this

[@brettpiatt9676]

So I have a 2008 yz250f I rebuilt the carb and put all new stock jets back in it. it runs fine except when I crack the throttle from idle it chokes and will die. I'm not sure what the problem is. any information would be helpful. thanks

[@HTMR]

You need a smaller leak jet: kzbin.info/www/bejne/eJTdq6GfmcZ3sJo

[@Juust_jake]

Hey I have a Yamaha 2002 wr250 f the screw you are turning what is the black one above that where does that need to be set at I can't start my bike now someone messed with it and opened it all the way please reply

[@HTMR]

Idle speed.

[@happyjuppi]

Hello..your vid helps me so much to understend how carb work..thanx much.. I have question..my bike run only on the hoke pulled out..when l push it in engine stops..what you thik it coud be?another thing..it is difficult to start the engine when hot And the question..the hoke..when is pulled out it deliver more fuel and the air as well?? Or just the fuell?? l tried to regulate it few time..but newer get done.. you think it could be small pilot jet? Fcr Mx39 Mixtur screew 2.5 out Mine jet 165 ( like in manuall ) Pilot 45 ( like in manuall ) Yamaha wr 450f 2005 Carb cleen It would be great to hear your opinion and tips what to do to get it run good..

[@HTMR]

Sounds like your pilot jet is dirty and/or your fuel screw is not adjusted properly.

[@mccdub305]

Do you have to have idle low when u start to mess with screw

[@HTMR]

It helps with the procedure.

[@brendanholmes6650]

I was wondering if you maybe able to help, I have an Rmz 250 for 08, I've shimmed it to the correct clearance, new piston etc but have contradictory scenarios, I'm blowing Black smoke ( rich ) but its running on ( lean ) any suggestions? Thanks

[@HTMR]

What do you mean running on?

[@brendanholmes6650]

@@HTMR Thanks for getting back to me. It revs on after releasing the throttle, I've taken the steps you suggested on the video, and there is a slight improvement, however I'm at 2 and a half turns and it still does it, I've put in the 45 pilot jet, I've tried a lot of things to stop it, and cannot get it to stop reving after the throttle is off, it gently reduces revs after around 5-10 seconds. Any help is really appreciated.

[@HTMR]

@@brendanholmes6650 Inspect the throttle valve vacuum release plate seal. Make sure it is installed correctly also.

[@brendanholmes6650]

@@HTMR Thanks very much, il look into that straight away, appreciate your time

[@SnipingWithSkillz]

Do you have the idle revs low just for tuning and then turn it up after tuning or that low idle is how it should be?

[@HTMR]

Low just for tuning so you can easily hear changes. Then raise idle after done.

[@anthony000izt]

hello, new to riding. would this help with bogging?

[@HTMR]

Yes somewhat. You want to tune the AP timing and reduce the leak jet size; howtomotorcyclerepair.com/fcraptiming/

[@theforester_]

Mate do you have any idea about why my carb sometimes take sometime to go iddle?

[@HTMR]

You probably have a lean hanging idle

[@markboucher7699]

hey matt i have an 05 kx250f and its had trouble starting. the hot start plunger screw (plastic) stripped out, and it had a 45 pilot in it. just wondering if the leakage from the stripped screw would affect the bike so much to the point it will not start?? i have to blip the throttle to spray some fuel in the motor before hand which will sometimes turn it over, then it quickly revs and immediately bogs after to a stall even if you give it throttle. jets weren't clogged and sliding plate was installed correctly

[@HTMR]

Is the hot start plunger fully seated even though the nut is cracked?

[@markboucher7699]

MatthewMCRepair the bikes all fixed now, put too much grease around/in the tps when i did the carb rebuild. i found that running it with the tps unplugged adds some good throttle response but can affect the idle a bit. i ordered a metal nut for the hot start so that should be all set now. feel free to spread the word on that tho, many people have the same problem i did. great videos and thanks for the help!!

[@HTMR]

Glad you figured it out.

[@mxice3174]

Hey Matthew I have a problem with my 09 yz250f the idle speed screw broke and it didn’t idle at all but it started after like 3 kicks and I rode with it like that for a while then just a week ago had a new screw put in and it started first kick and idled but now it has a bad hanging idle and takes of like the throttle is sticking but it’s not it’s smooth it doesn’t bog or anything it just will go by it’s self at like 15mph and if I pull the clutch in it revs way up and it’s super hard to start it when it’s hot now when before it started up just fine. I’m not sure if you will be able to help but thanks

[@krishermanowski3599]

This was 7yrs ago so I don’t know if there will be a reply but my bike is weird. It’s a 2002 suzuki quad runner and if I turn it in all the way it just revs up and doesn’t die and idle hangs but if I turn it out to factory setting (1-3/8) the idle still hangs. I turn it out to 4 turns and it idle better but shoots some black smoke. But when I ride it at times on the 4 turns out it hangs the idle sometimes. I have no idea if it’s running too rich or too lean.

[@HTMR]

Weird. When was the last time the carb was cleaned? Check for vacuum leaks also.

[@gamtamix836]

Hi all, I have a yz250f, note I'm very new to bikes, so when I pull out chock I can start it so naturally the revs are higher but after 3 min of idol when i go to put back choke the bike stalls is it the same problem than this, hopefully it is because I just wanna ride the thing 😢

[@thebraapbros3037]

if your bike won't start and you think the fuel screw is the problem should I start at 2 turns

[@hamsandwich9311]

Hi Matthew, I have a keihin fcr carb and a tusk adjustable fuel screw. Bike runs great but does not stay idling without a little extra throttle. There is no idle screw, only a fuel screw. Is it okay to adjust the fuel screw to get the idle up, or no? It runs great so I don’t want to mess with it if it won’t help.

[@HTMR]

No, do not adjust fuel screw to adjust idle. That carb should have an idle adjust, if not, buy the part.

[@Y2daT420]

the idle adjustment is a flex screw the threaded end goes in where u connect the throttle cables the opposite end goes to the left side of the carb and attaches to the carb bowl screws