Jetting a must after other free mods?

5 replies to this topic
  • Usedup

Posted January 30, 2009 - 07:33 PM


I'm in process of going through a 2000 WR400 bike that has not run in a year. I have carb. off for cleaning and going over. How do I know if throttle stop has already been done? Original length vs. mod? If I do airbox,throttle stop, and grey wire, and pull end plug out of silencer is re-jetting automatically required? I know you riders hate these same questions repeatedly, but read through about 20 pages of postings and did not see definitive answer. I'm in N.C. where elevation is not a real concern. I'm new to this bike and still learning. Thanks for input.


Posted January 30, 2009 - 09:13 PM


I don't know if the 2000 even had a throttle stop or grey wire... my 99' didn't but it was a Canadian model.

Jetting will not necessarily be required after those mods... no guarantee but you'll know once you get out and ride it, the good thing is that those carbs are relatively easy to access and work on.

Do your free mods and try it out... I don't think removing the pea shooter and opening up the airbox will account for more than anything that can't be compensated with the fuel screw.

  • William1

Posted January 31, 2009 - 02:23 AM


If you open up the air box, then the main jet will have to be changed to a larger one. This may be a good time to invest in a James Dean jet kit and a Merge Racing extended fuel screw.

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  • flyer05

Posted January 31, 2009 - 06:15 AM


I have a 2000. Yes on the gray wire. (not on Canadian model) Yes on the throttle stop.
Good luck

  • spunalot

Posted February 02, 2009 - 09:48 AM


I did all mods plus a titanium DSP pipe on my 99. I am at sea level and run a 180 Main Jet. I also run my idle jet at 48. It runs great. 180 was the recommended jet from the pipe manufacturer.

  • Usedup

Posted February 02, 2009 - 10:10 AM


As I was de-gunking the carb. I made note the main jet was 158. With the stock exhaust with end cap removed, what is your best swag for main jet vs. yours with aftermarket exhaust?


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