Help In Texas

3 replies to this topic
  • Bob Pearson

Posted June 15, 2005 - 05:45 PM


Hey Guys I really need help. I have a 1998 WR400F thumper that has a rich fuel condition from part throttle to wide open. The bike cranks and idles very good. As the engine warms us it starts to run rich at part throttle. I have overhauled the carburetor and checked and rechecked every circuit. I have a manual. I have tested every electrical circuit and every electrical part.
I have even cut the gray and the blue wire on the cdi unit. It did not make a difference. I have replaced the cdi unit still no change. I have changed the needle jet to the leaness setting. I have also changed main jet from 168 to 150. Plug was leaner but condition was still the same. Also I have checked
valve adjustment and for vaccum leaks and everything was good. I would appeciate any help. Bob

  • slotracer577

Posted June 15, 2005 - 05:52 PM


Have you done the mod to the accelerator pump, so it doesnt shoot too long. BK mod I think it was called. My YZ was used to flame out due to too much acc pump.


Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Bob Pearson

Posted June 15, 2005 - 05:56 PM


No I haven't. What is a BK mod? Thanks, John


  • Dirt_rebel

Posted June 15, 2005 - 08:02 PM


1998 wr400 runs wif the first generation of fcr.. u cannot do a bk mod on those carb..u mite wanna do a search on taffy mod for those carb..cheers


Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.