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Jetting ?
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Posted by: wagsracing

I have a 2003 KFX 400 with a yoshimura comp full-system, K&N Filter and stock air box. I purchased the full power pack which came with DJ main jets. Im currently running 3 down on the needle, 146 main and 3.5 turns out. Sounds great in idle and low end but when I get on the gas it starts to spurt and sputter. I think it is to lean. It sounds like it wants more gas? Can anyone put me a little closer to where my settings should be? Its seems like several people are running a 160 main jet. Feed back would be appreciated.

Posted by: nemesis

not sure exactly but you should go up in jet size. Go to yoshimura's web site and the have a jetting chart. Albaaction.com has a chart also.

Posted by: quad

Lid on or off?I assume its on.You are too rich!!Go down 1 size until the cutting out goes away.160 is waaaaaaaaay too rich for your mods too.

Posted by: Mobile Dyno

Do not go down!! 155-160 should do it. Those are the sizes that I have gotten with the bike on the A/F meter

Posted by: quad

AHHHHH i see now,yeah u may be lean,because DJ uses different numbers than mikuni.Therefore,you are runnin about a 136 mikuni.A 160 DJ may get ya on.But a mikuni 150 will be close too.

Posted by: wagsracing

Thanks guys, I will try that

Posted by: wagsracing

I went with the dj 160 main and 3 turns out and I am right on. Runs great and my spark plug was a nice golden brown. Thanks guys