My boyfriend spent a week trying to fix his bike and I watched this video and ended up fixing it in 5 minutes. Cheers mate.

This is one of the most useful videos i have seen about this problem, ive had my carby fed yz for nearly a year now and no video ive ever watched could fix it like this it was so simple to follow thanks man youve earned a sub

Thanks for the video! I have been fighting my carb issues for a while - cleaned it like 4 times. I tested the intake as you showed and it appears to have a leak so no wonder I can't tune my air/gas intake and probably the reason for all the backfires. I took the intake off and it looks warn so ordered a new one so will see if this fixes the problem. You are the only one that has shown this method - and I have watched what seems like a million videos now! Great work and thanks for posting this!

My drz400 is doing the same thing but I think it's the slow jet on the carburetor. Thanks for the video I'll check what u did as well.

tnx for posting this video i have the same problem wid my 4stroke bike now i can fix it becoz of ur video...

Great video very helpful thanks Vegas Romaniac

nice.. ive pretty much done everything i can if my bike still dont run right after i install the carb im gonna try that carb cleaner vaccum leak trick

Great job!! Thanks for useful information!!

I’ve had the same problem before and it ended up being a cracked carb boot. Was letting air in and leaning the mixture out. Pretty common problem with after market air filters because when you remove the air box it lets the carb flop around and ends up cracking the boot.

Thats helped me with my kx250f. Thanks!!!

People commenting below are so uncertain as far as which is "lean" or "rich" on these bikes. When it pops and is hard to start - it is definitely lean or sucking air (or not getting enough fuel inside the carb). Same with all of these 4-strokes. There could be air leaks in seals and gaskets - but also the Pilot jet is possibly clogged. You have to remove the pilot jet, inspect the jet for blockage. Because if a pilot jet is blocked the bike will sound just like this one did. Some people just blow compressed air through the jets in hopes of clearing blockage - you likely have to simply replace the pilot jet. Funny how people think popping out the exhaust means rich. No no and no. It means Lean Lean Lean. Difficult to crank also means lean lean lean. Simple as that.Air can also come thought the hot-start plunger. Another common area that few people inspect for issues. That area inside the hot-start needs to be cleaned, and the o-ring needs replacing periodically. Any extra air coming in will cause these bikes to pop and hard to start and stall. This also comes from blocked jets as well as many possible reasons.

Absolute legend!! Saved me so much time

Very helpful video. Cheers

Thanks man... very helpful :)

Nice work!!

Great Video. Thanks. 1974 XL250. Almost there. Cheers!

Awesome Video thanks

Thanks for video man !!

Very informative thank you

I think this is my yz450 problem . Nice vid👍

it is the little things that make a big difference. valves adjusted, no air leaks, carb functioning as it should, good spark. amazing how the little things make all the difference. a little TLC goes a long way.

Great information Thank You so much. God Bless.

I'm like.... that baby is lean..... then you went to the carb and found the air leak.... well done!!!

Thanks Mate!

thanks dude

thanks!

Thanks, great video 👍

sir how can i adjust my 4 stroke gd110 same as ur problem.. thanks for ur answer...

Gotta check the timing chain on my 04 it’s doing similar still. Doesn’t like to idle except occasionally. Keep the rpms up it’s good but has this tendency to surge itself. Ordered carb rebuild kit and when it comes then it’s getting valve and timing chain check and if I can find someone with shims so I don’t have to spend another $70 then it’ll get adjusted too!

Good info man!

I didn't know to test for this. Thanks!

great work sir, i really appreciate your help, i prob have same problem

Thanks. You helped me out. Had same problem 👍🍺

hello great video! did you solve the engine noise? i have exactly the same model and the same chain/bearing noise on gas, should it be any bearing?

Good work bro😎

Ok my pitbike has a brand new carb it won't stop leaking through the overflow and spits gas into the the airfilter on my ssr 110 and as soon as I give it gas it dies I tried adjusting the mixture and it did nothing plz help oh and it backfires and shoots glame when I rev it at full throttle

Hey man... sorry to bother you. Just bought a 2008 KTM 250 cx-f. She stalls until warm without tiny throttle blips. Would it just be the throttle screw on the carb do you think or wrong mixture? It runs mint when warm

good job my bike do the same

i made an gasket for my bike from steel im gonna test it tmmr

you're a wizard Harry!

Awesome stuff I think this was my problem

i think i have the same problem with my yz250f09.. i was just riding my bike and all of a sudden it wouldnt idle and started backfiring like crazy.. it would only run on choke. so i cleaned my carburetor thoroughly assuming it was just one of the jets put it back and still same problems. wont idle and only runs on choke. And i stumbled on this video and checked my intake boot.. there it was.. so many massive cracks. do you have any tips on fixing the intake boot? how did you fix yours with silicone? is it still holding up to now? parts for my yz250f are just so damn hard to order here in the Philippines.

Fair play for fixing timing issue and finding the air leak but that engine doesn't sound health, with all the dust getting sucked into the engine i'd be tacking the engine out and stripping it down... It sounds like its nocking, maybe bottom end bearings... And check for piston slap. Give it an oil change and check theres no metal paste in there lol

The "pilot screw" under the carby plays a pivotal role with initial idle. The Leak Jet (plastic idle screw on side of carby to be adjusted after. Exhaust popping / backfire with these machines means and in particular in this case - too much fuel is entering the carby and excess fuel exits via the same passage and it is then combustive by the heat of the exhaust and pops. Meaning your mixture is too rich and yr air duct system is choking and drowning and not enough air is entering the system to get the mechanics right. The best way to get yr bike back to its norm, is to kick start (compression) cold-start or choke (side pull out plug), let it run for 2min (this basically bypasses the correct air fuel mixture system and is basically the best way to start your bike), give yr accelerator a few hard twists, listen to the amount of popping and how yr engine revs after giving it a few full twists (more backfire and free run of the revs means more tightening of the pilot jet). The bike will then choke out in the above case. NOW - Turn yr pilot jet clockwise a turn for now. Restart the bike without the choke. If it conks out again, turn it again the same amount. This piloting gives you the first indication of your carbys nature. If you get it going, then play with the leak-jet or idle screw (without choke). I've seen 5-10min videos on loosening yr carby, turning it to the side draining my megabytes. But kudos to the video maker for effort. The best way to turn your pilot jet is to use a flathead socket piece that fits in the barrel (if stock), mark the side of the screw facing you and turn with socket with yr hand until the marker returns to same position. Literally a 30 second job plus adjusting the clutch so the bike doesnt jump too much or at all and enough air and fuel is defined for take off. Thankyou. *This is only my own opinion*

Hey Man I have backfiring issues when starts & dies out first 30 seconds it's a 250 yz fuel injected 4 stroke any ideas?

Was this a 2002? Mine seems easy to stsrt and I got 2001 to that's got something wrong with it and even that has shit load more compression then this other one I got that starts first second kick but it's stop lately and will start easy but won't stay idling and won't start on any off the chokes but I think it may. Be a valve ajustment hopefully it's not new cam chains and shims lol that art me back 580 on last bike I got done 😬 rather kusg get the bike rebuilt for an extra 1500 lol the bike ones people but had very low compression and its a 02 yzf

Good job ! Man im stuck on this project bike i bought to do a cafe racer build. Its an xl600r and i cleaned the carb. tried different jets etc adjusting the af needle. Thing pops bad at idle. You can rev it to the moon and back but idle it just struggles. I can turn the idle knob up to where its a high idle but its just too much. Some people i've talked to think its the stator because its old. but i have no clue !

Dude thankyou that's like a video of what I've been reading haha I've bought a crf 450 r cheap and now need it to run. It bumps fine but is harder than shit to start of a kick and doesn't without throttle :(

golden*

I need help wit my 2012 yz450f please anybody that can help me get my bike crunk scine new top end and head i think my timing off or values need adjusting

Yesterday I was riding and held it pinned in 5th gear for a little too long. Now my bike backfires, it won’t idle but it starts and it only runs or stays on at high rpms so I was able to bump start and ride it back. Does anyone have any idea where I should start? I don’t think the carb is dirty I just rebuilt that a month or 2 ago

shim valves or clean carb

Good job 👍🏽

What should the cams look like when the chain is aligned properly? I think this is the problem with mine. I’ve rebuilt/cleaned carb three times and it stays running rough. Backfiring, bogging off zero throttle etc. I plan to pull the head and check valves and want to make sure the cam chain is aligned properly.

Thanks man this video was really helpful my bike had the exact same problem

This ironic. This is an old video. I just bought a 2006 yz250. I think its this bike!!! I just got the bike cleaned, rebuilt the carb, serviced linkage bearings, it was all nasty and rusty bearings. Other than that bike runs and starts good. I have to use the hot start lever. The only thing that bothers me, smokes leaking out of pipe joint.

Clean your carb. My brothers KX250F had the same problem. Carb clean, and it should be fine. Put in the carb clean with every fill up

I've cleaned the carb entirely, put in a new carb kit, put in a new carb boot, adjusted the valves, new throttle cable, hot start cable, and my 2005 WR250f still won't idle properly. The bike will climb RPMs all by its self out of nowhere. I think it could possibly be a computer issue but I really don't know much about engines so any help would be appreciated.

Got a 2005 yz250f won’t idle and keeps stalling when I try to take off

I need help I have a 02 yz426f starts first time every time and idles great but when you give it gas it pops and backfires really bad

Hey man I don’t know if you will see this but just got a 2009 crf250r. It’s backfiring really bad, I cleaned the carb and cleaned out the Jets. It backfires while idling sometimes and on the decel. I don’t know what to do.

hey, ive got the exact same problem with the high revving, no idle and backfiring. theres definitely a vacuum leak however did you actually adjust the timing or did that not need adjusting? cheers

Hello I live out in Pahrump and having problems jetting my crf450r I got it to run but my bike is jetted way too much and shouldn’t be running

I have a 140 pitbike and mine is doing same can anyone help please

POV: You finally find the perfect video to help you with all of your problems.

i damnsure cant rabbit kick my 99 yz400f and for damn sure anit kicking it wuth that kind of shoe either i got a leg for kick starting a bike been kick starting my old shovelhead 96 c.i i dont know how there doin it why dont my yz400f have this hot start all i got is the compression release

how come my bike runs sweet on choke and when u switch chock off it dies

Mine doesn’t pop whole it’s idle but backfires when you let off of gas a little and it won’t kick start only push and has a rough idle if it idles at all

my rmz 450 2007 (carb) works fine only with choke on... why????

I have a 2008 yz450f its popping when running really hard to get to start and when its hot almost impossible to start I've check for air leak at the same place but no leaks fuel screw 2turns out but it dosent seem to male a difference

Hey I have done everything from putting the valves in specs to timing to cleaning carb checking for leaks and still can’t figure out why my bike keeps backfiring. It happens every time I release the throttle 3 pops every time. I’ve played with the fuel screw I’ve played with the idle screw and the acc pump which has brand new diagram and gaskets in it. Any suggestions???

I bought an 09’ yzf250. I have the same problem. Did a carburettor rebuild and it won’t even start. It was running before it, but popping and banging a ton. And now the rebuild is done, it doesn’t start. Please help

I need help I have a 04crf80 that I can't get to idle or stay on with out giving it throttle it's starts write up first kick carburetor has been cleaned and tuned but still can't get it to stay running with out giving throttle but what I notice is when I ride it I get alot of popping sound coming out the exhaust like in your video

my bike wont idle but as long as I have a little throttle it purs like a kitten; I dont think it's the jets because just did a rebuild kit; as soon as I let off the throttle it dies; yours had a fast idle mine starts fine with a twist of the throttle & dies as soon as I let off the throttle; what do u think

I have the same issue but I have fuel injection

Did you end up adjusting the valves, or was it just an air leak?

What about when i rev it and then let go and it goes pop in the exhaust is that the same?

If I drive my bike and get on the throttle once I get full throttle my choke comes on and then my bike bogs down and dies how do I fix that?

I have a 2005 yamaha yz250f, bought it 4 days ago. The problem is that its really hard to start if the engine is cold. When engine is hot, it starts at first kick. And my bike won't idle, when im driving and pull the glutch and stop, rev stays good for a moment and then rev drops. Sry my english, im from finland and I cant focus properly

Is the back fire bad?? Because mine does it too but it sounds fire af

Adjust the valves

how come my dirt bike won't idle without the choke on do u think there is a leak of air because my idle flathead screw does not fully work like I need it too idle more and it does not like he does nothing for like 6 turns to the left like wtf plz help

I have a Honda crf 250r 2004 doesn’t start it just backfires when I try kick starting it. Can anyone help me figure out this problem please I would appreciate

Or carb needs cleaned

My bike is doing the exactly the same thing

Running rough, dry black plug. Backfire out the exhaust every so often.

I was having this problem turns out I forgot to tighten down the clamp

This is exactly whats happening to my 06 RMZ250 it starts up fine and once i turn the choke off its bogs out , and when i rev it or ride it backfires , and my bike never backfired

Just like new

My RMZ250 EXHAUST KEEP GOING RED , any advice ?

I cleaned my carburetor like 7 times. Didn't work so I just bought a whole new carburetor.

AYE im in vegas can you fix my bike?

My bike runs perfectly fine but it does make a crackling noises often any help?

I have a 2008 Yz450f and people say that they have the most reliable engine.

it damn sure dont have no compression cant rapid kick my 99 yz400f like that

My buddy has the same bike and the same thing happens where it backfires a lot

Wait so my dirt bike isnt supposed to backfire? Edit: it is not hard to start only backfires when i let go of the throttle.

my kx 250F is way way way harder to kick over than that bike !!

Sounds like mine

mine backfires instantly then cuts out instantly urs stay on way longer