2004 YZ450 carb mod

3 replies to this topic
  • BBrown626

Posted December 14, 2006 - 10:59 PM


I did a lot of reading on here, thumperfaq and motoman393. It isn't clear from the reading, so I ask you all:

Is the BK mod necessary/recommended on a '04? How about the P-38?



  • Fastest1

Posted December 15, 2006 - 05:58 AM


The P38 was for 99 an older 400's and the BK/GB Mod was for the 2000-2001 models. Yamaha seemed to have worked out the overshot of the accel pump by then.

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  • grayracer513

Posted December 15, 2006 - 08:45 AM


I'll tell you for a certainty that my '03 needs no help whatever in the throttle response department, and has no mods to the accel pump.

  • BBrown626

Posted December 15, 2006 - 06:00 PM


Thanks guys. I am pretty happy with my bike, but someone advised me to get the mods done. He had an older bike though.

Grayracer, I found a pinched clamp on my crankcase vent line and bent it back. I went riding today without blowing the cheap plastic plug out. Your recomendation was spot on! I really appreciate your efforts to help us lesser experienced mechanics.

Thanks again,


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