2000 wr 400 acceleration pump

4 replies to this topic
  • metallicarebal

Posted February 04, 2007 - 01:22 PM


i just got my first yamaha and im kind of stumped, i have read the threads on fine tuning the acceleration pump but they seemingly pertain to only the 426 and up carbs. i have had my carb off and see no way to adjust the acceleration pump in any way unless the tension from the spring that actuates it can be changed. it is also possible that i need only to play with my jetting because i have noticed that when the bike gets hot the header glows cherry red, if im not mistaken that is a sign of jetting problems? any and all help and opinions would be greatly appreciated. thanx

  • SXP

Posted February 04, 2007 - 02:16 PM


The Taffy Mod is the only adjustment you can make to the Accl Pump circuit on this generation FCR carb. Link follows:


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  • Team_Oatmeal_Pie

Posted February 04, 2007 - 07:37 PM


The Taffy Mod is easy. A Boyesen quick shot also will do the job.
As for the header, all the WR are jetted lean and the header will glow when the bike is not moving, more noticeable at night, even when you ride then stop for a minute or two. I would focus on the getting rid of the bog and not so much about the header getting cherry red when stopped.

  • Oasis_Flame

Posted February 06, 2007 - 12:19 PM


I never had a use for the Taffy mod, I cured the bog by using the pump adjusting screw, right side of carb. I ended up turning the screw clockwise a full turn an a half from factory setting when job was done. I have zero bog at all times.

01 WR 426

  • metallicarebal

Posted February 06, 2007 - 03:36 PM


Thank you for the replys i will definately try the taffy mod, i need to address several other issues with the bike and check the valve clearance as it seems that the dope that had it before me beat it and did no routine maintanance whatsoever :censored:. The air filter is a ball of grease, there was barely any oil in it, brake fluid was very low, and there are all kinds of miscilanious nuts and bolts missing. So, im going to check her over good before i take her for a good long ride. any other suggestions would be greatly appreciated. thanx again for the replys


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