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2002 YZ426F Jetting
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Posted by: JOE WHITCOMB---------------------

I need jetting help with my first 4-stroke. I ride @ Speedworld in Phoenix AZ @ 1250ft above sea level, mostly in the morning right now it is about 60 degrees. I am having trouble getting the jetting clean.

Posted by: Kramer---------------------

What jaet do you have, what have you tried?

Posted by: JOE WHITCOMB---------------------

#162 seems to lean, #168 seems to rich, I just bought a #165 and will try it this weekend. The problem is I have trouble telling if it is lean and rich. I have trouble with popping when I let off the throttle. Is there a good starting point to solve jetting problems.

Posted by: Kramer---------------------

read this article Patrick Burns Manual

It's a good intro to the Keihin.

The needle clip position will make quite a difference too.

If the popping is after the throttle is closed you can unscrew the FUEL screw a little at a time. A little bit of a pop is OK.

Read up on the "BK Mod". Sometimes the accelerator pumps are set to squirt WAAAY too much fuel. That will make it very hard to judge rich/lean conditions.

If you want a real education on 400/426 jetting check out the volumes of info put in by Taffy, and James Dean at Thumpertalk
just search for jetting. The amount of info is unreal.

Posted by: DPW---------------------

Quote:

If you want a real education on 400/426 jetting check out the volumes of info put in by Taffy, and James Dean at Thumpertalk
just search for jetting. The amount of info is unreal.

I second that thought

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2002 YZ426F Jetting

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