How-To: 4 Stroke MX Fuel Screw Adjustment YZF CRF KXF RMZ FCR Part 2 of 2
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- เผยแพร่เมื่อ 30 ก.ค. 2015
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Products used in this video:
Tusk adjustable fuel screw
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40 pilot jet
amzn.to/1S94FND
42 pilot jet
amzn.to/1MSrRcj
45 pilot jet
amzn.to/1JqtJKi
48 pilot jet
amzn.to/1JqtM9b - แนวปฏิบัติและการใช้ชีวิต
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
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!
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.
Did it work after u adjusted the screw ?
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 🙂🙂🙂
Best explanation to this 4 stroke carb tuning. Great video thank you.
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!!
Thanks for the help brother from Sacramento, Ca.
You are the man !! Very well explained thanks
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.
Great video just bought a bike an it wouldn’t start , did this and she fired right up easy an to the point 🤟
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
Cool. Keep me posted on outcome.
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
Yeah, it takes some effort to get to these carbs.
Great clip huge help . Detailed and clear thanks
Great job on the video.
Thank you so much this fixed my hot start issue
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.
Mein, this is the perfect explanation. Best ever 💥💥💥💥💥💥💥💥
Awesome video very good info!
I will try this out on my crf, good video
Thanks, Exactly what I needed to solve my throttle hanging up on my freshly rebuild 250F
Same
did u just turn the fuel screw and it fixed it ?
@@rileyduff6604 yes. I bought an aftermarket fuel screw, installed it and followed his instructions. problem solved and I learned something.
Brian Rose cheers bro yeah i fixed mine but i still have stock fuel screw was so hard but i got it
Sweeeet video!! Thanks very helpful 👍🏾
Great info thanks!
I'm gonna try it when i get home today...hopefully it will help with the bike not wanting to idle
Awesome and to the point, thanks! I found out my hot start was corroded in the open position and causing a similar popping..
What is a hot start? My rmz 250 pops a little But when i start it the pipe gets red
This was very useful thank you 😁
Great vid bro, thanks!
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
great tutorial, thank you!
Your welcome.
Thanks for the help
Nice! Most of the recent carbs, especially the ones with a plug over the set screw, come set too lean for emissions reasons.
Thanks helped a lot
Awesome thanks!!
If in doubt rule it out.
Runs better but still popping on decel.
I care not as the power is smooth.
Great info, thanks !
Perfect thank you!
Thanks this will help I hope. If not I have another problem.
i was adjusting the fuel screw thinking it was the idle air valve hahah,thank you for the info
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
125cc what? Best thing to do is get a service manual and read the maintenance section. It will explain what you need to do.
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
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
I have vids to clear the bog.
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
Nice video. How many turns does the pilot jet get?
Thanks for the vid, One question, if the screw Is all screw in, (leaning) the bike must stop?
Great video, could you do a Honda Navi is a 4 stroke engine too!
Thanks fixed my throttle cutting out
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
Otimo serviço
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.
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
BOA noite meu ktm sxf450 quando está mais quente fica a afogar tem alguma ideia da solução ?
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 :)
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??
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
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
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
On my '05 WR 450 i have it running perfect but alot of popping on Decel, what can I adjust.. Ty..
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!
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?
You have a lean hanging idle. Adjust fuel screw richer.
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.
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
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.
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 .
Yes, this applies for all FCR carbs.
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 ?
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
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?
Nice
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 :(
On which carb must i start if have 2 carbs? Suzuki intruder vs 800 1994
Thanks
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
Do you do it with choke in or out?
Matt, great video. how would I go about draining the fuel on my 06 kx250f?
Why drain it?? Loosen the 17mm bowl nut.
Thank You for the video. I just got a full yoshimura exhaust for my yz450f . Do i need to change jets size or any other carb adjustments?
+Gennaro Scotti Yes. Visit their site to see if they have recommendations on where to start.
My 2010 kx250f is backfiring so much when i release the gas so is it running too lean?
What’s the exhaust you got on that?
got a kawa 2011 250f there comming fuel to the karburator but not feeding it to the engine whys that?
hey man, my bike will bump start but not kick start. any suggestions? 04 kx250f
Need help, I think I
have a 49cc 4 stroke Motor. How do I connect and idle the carburator?
Can this cause ticking noise ? Other then valve or tensioner
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
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?
Year make model? Stock pilot jet? Any mods?
@@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)
2021 Rmz 450 revs too high during cold start when choked?
Hey bud, i have a 2007 KTM 450exc, i recently bought it from someone and the bike had a lot of popping during deceleration, so i thought it was running lean.. so i bought a adjustable fuel screw and cleaned the carb the best i could with the carb spray.. the bike was set at 1 1/4 turn on the stock screw, but when i do the adjustments it will shut off at 1/4-closed, if i turn it open it will rise in rpms around 2 1/2 turns, then by 3 turns the rpms dropped some already.. i tried to run it at 2 1/2 turns and it gets boggy occasionally when you crack the throttle and during decel im seeing flames occasionally.. so i turned it leaner to 2 and thats where ive had it since, but it just has a ton of popping during deceleration...
+storxusmc How old is the muffler packing? Any exhaust leaks?
is the carburetor Same as pz30b carburetor with acceleration pump and slide
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?
Sa.e problem on my 07 rmz 250 throttle hanging up too long
Hello in need of anyone’s help, I have a 2003 yz250f my problem is number 1 it’s hard to get it started unless it’s rolling and number 2 it will not idle for 1 second unless you are constantly giving it throttle, once you start the bike on the roll it will run through all the gears like a champ but will not idle, the idle screw appears to be faulty but not sure I haven’t found any information on what your bike does if the idle screw is not working. Thanks In advance
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 ?
How many turns out are you?
My kx450f 07 won’t start there’s Fuel in and the choke is on can you please fix this adjustment
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..
Sounds like your pilot jet is dirty and/or your fuel screw is not adjusted properly.
Hey does anyone have any idea on why my 2004 rmz250 is having problems with high rpms fine in low rpms but in high rpms it is allmost like it’s anti lagging and not letting me past about 4.5 thousand rpms sometimes it will get more sometimes it will get less any ideas on what could be causing the issue
I was thinking it’s not getting enough fuel?
It back fires and splutters when I’m in high rpms I can even get up a hill climb in 2nd gear it just wants to die and splutter and backfire ect
Any info and clues would be so appreciated cheers team
if your bike won't start and you think the fuel screw is the problem should I start at 2 turns
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.
Use light finger torque and seat it until it stops. Use very little force and you will be OK.
Would this fix a bike that feels like it’s sputtering and backfiring?
Is it the same for the twin air
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
That happens when fuel screw and/or pilot jet is too rich.
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?
Remember the fuel screw is upside down. Lefty loosey is richer.
I recently bought a 2004 KX250F and I bought it as a project and it needed a new cylinder head and all new valves so I replaced all that and it starts after like 40 kicks maybe with the choke and I cleaned out the carb and jets and the valves are in spec. It’s also has stage 2 hot cams in it so idk if that makes a difference on what the fuel mixture screw should be set at but it’s hard to start and has trouble running nicely so any other idea on what it may be besides the fuel mixture screw cause I’m stuck
I feel it’s most likely a carb issue but u really don’t want to spend anymore money on a new carb
@@kevinriess Did you adjust the fuel screw per this video?
MatthewMCRepair yeah I adjusted it to 2 turns out and it did start but after warming up for a little I turned off the choke and died a couple seconds later. Now would you need different jetting to accommodate for aftermarket cams or can you use the stock jetting?
@@kevinriess You need to adjust it while running. Engine warm choke off. What pilot jet size are you running?
MatthewMCRepair I just took the jets out and I running a 42 pilot and 175 main. Is that ok?
Hey bud, i just had a major malfunction in the top end. We got it repaired with new cylinder and valves we redone, timing was put to spec, new rings and everything. Before this, we also replaced wire harness and a few other ignition parts. It starts cold and runs perfect with no bog, pop, and hesitation. Rides fine, power hits hard. After riding it for 10 min getting up to temp. We stopped, turned it off, and see if it cranks again. And does not. Will crank cold, but no hot even after all those parts. What do you think??? Thanks!
So... What did you do to fix it??
So if my rpm drops slowly it's rich?
great video, helped me a lot. regrats from brazil
After a blip of throttle yes.
@@HTMR 1:35 but you said if rpms hang you gotta richen it up. So is it rich or lean if the rpms hang?
@@dantsy6397 hanging rpm is lean
How about the air idle mix how many turns min. And max?
Hello.
Sometimes when i ride at the track, and i come to a turn and i pull in the clutch - the engine stops, because the idle speed is not high enough. Do I just turn the idle screw? Or do i have to mess with the fuel screw?
Also it struggles to stay idle when its cold.
The bike is a 2016 and its pretty much brand new.
Perform the fuel screw adjustment and let me know if things improve.
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?
Start by tuning the fuel screw.