06 yz450f backfire Help!

[IamRooster151]

my 06 450f backfires quite a bit (more than usual) carb was clean and the valves are clean and has fresh gas, dont know what the problem is. help me identify this problem and ho to fix it

[curtis515s]

my 06 450f backfires quite a bit (more than usual) carb was clean and the valves are clean and has fresh gas, dont know what the problem is. help me identify this problem and ho to fix it

Your stock pilot jet is a 42. Replace it with a 45 and almost all of the popping will go away. Some run them even richer than that but a little decel popping is normal. The 45 pilot made my 06' much better. It's the best $ 5.00 you'll spend on your bike.

Edited January 6, 2011 by curtis515s

[rasta]

did you check the valve clearance? maybe adjust the mixture screw as well, none of my yz's would back fire on decell unless valves were off or mixture screw was off setting

[Mike Martel]

jd jet kit did the trick on my yz450f.

[ForsheeMS]

I think Curtis hit it. The pilot is a little lean, especially with the colder temps now. Make sure you don't have an exhaust leak anywhere as that will cause the popping too but the pilot is most likely your problem.

[hillclimbguy]

Some good advice. I did the same thing on mine. Richen the pilot!

[alliance52]

I had a truck with a straight 6 motor on LPG it use to backfire really bad if the timing was retarded. Just a thought hope this helps.

[racertodd]

I had some backfire issues with my 06 yz250f as it ended up the hotstart cable didnt have enought slack in it. It wouldnt close all the way. Maybe this is the problem could be not enought slack or possibly not moving free and maybe the hot start is opened a little. Just a thought hope you get it figure out

[03cr125r]

im wondering if a lean pilot would cause it to not idle