yz426f jetting specs advice

3 replies to this topic
  • yama02yz250f

Posted May 25, 2008 - 08:45 PM


Im not sure if this should be in the jetting forum or this forum but you guys have never let me down so I went this way. I am tearing down most of my bike for various maintenence and decided to verge into the carb for the first time. I have cleaned everything out already and just wanted to see if my jets are correct for my conditions. The bike is not starting to well cold(usually takes around 6 kicks) but starts in 1 or 2 when warm. However, the bike is popping on decel heavily....very heavily. I have an adjustable fuel screw it really hasnt fixed the problem.

I have a 42 pilot jet and a 162 main.
Its currently changing in weather from 60-85 degress and getting warmer(I realize this is a big range)
Dont know humidity but i live in the pacific northwest in western washington if that helps.
I ride from sea level to 3000 ft(I realize this is a big range too.
Everything is stock but I do have a 450 cam and pro moto endcap with sparkarrestor.
Oh and its a 2000 yz426f

Basically the bike isnt running horribly but I wanted to see if these jetting specs seem ok for my area of riding and if not what I should do.

Thanks in advance as always!

  • zuch95701

Posted May 27, 2008 - 09:08 PM


since it is starting bad cold i assume you are choking it. you might wana go one step richer on your pilot jet it sounds like you are lean on the bottom end. On my old 01 426 with a similar set up i ran the jd kit fixed all the issues.

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  • 642MX

Posted May 28, 2008 - 05:37 PM


Buy a JD jet kit and use the recommended specs in the instructions. You won't be disappointed. :thumbsup:

  • SRT426

Posted May 28, 2008 - 06:43 PM



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