question on ap mod on an 08 450f

3 replies to this topic
  • thmlrmg

Posted June 25, 2009 - 06:11 AM


I have a pretty good low end bog and I was looking at doing the ap mod on the 08 450f. When I checked the throttle closed and wide open the ap lever is against the set screw the whole time. I took the ap diaphram out and the rivit is pretty short already. What can I do to help take the low end bog out then. I am running a 55 leak jet now.

  • r1usn

Posted June 25, 2009 - 06:26 AM


I had the same issue when i got my 450. A fast easy fix, is to wire ap linkage together. I replaced the AP spring itself to a much stiffer merge AP spring. I have done that on both my drz and yz450 now, and for $15 it is very worth it. The new spring can be a bit difficult to get on though.
You may also want to check the timing of the ap squirt. A gap of 0.100" between the ap linkage and the screw holder plate worked for me. If you decide to do it by measurement, make sure that you measure the gap on the throttle wheel side. The other way to do it is to remove the airbox and watch the squirt. You want it to just miss the slide when you quickly twist the throttle. Also do a quick search on ap timing and you will get some more detailed posts on how to do it. Hope this helps. Its a different bike afterword.

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  • grayracer513

Posted June 25, 2009 - 06:28 AM


Jet it right and learn not to snap the throttle open.

  • hyperflow

Posted June 27, 2009 - 05:56 PM


i put a scary fast AP cover, O-ring mod and jetted my bike with a 45 pilote and 168 main, runs like a champ now. Can;t make it bog if i tryed.

Also 08 yz450f

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