Jetting question for WR400F

I am getting ready to add a power now valve and a FMF power bomb head pipe to my bike and I wanted to know if I need to re-jet it or if it will run good just by moving the needle position. Does anyone out there have either of these items on thier bike? If so, did you notice a difference in the low end? Mine bogs real bad and I'm trying to remedy that.

Thanks for your help!

What year 400? To help with the bog you can do the accuator mod. There is alot of different jetting suggestions, just use the search and look for your locality conditions. Good luck. :)

Read all the Jetting Q's pages at the top of subjects list, or save yourself about 100 hours of work and buy James Deans kit here at the TT store. I wish I did :)

It is a 2000 model. What is the accuator mod. I am really new to this motorcycle, and I'm not quite sure about all the lingo yet. I will check into the james dean kit. I'm gonna talk to the dealer, and see what they say. I'd like to stay away from buying an entire jetting kit. (wife already goes nuts about the money I put into the bike)!! I'd like to just go buy the specifis jets. Thanks for all you input! Also Is there anyway to tell, if a WR have been taken to YZ timing or not. I tore open the head cover, and I didn't want to fiddle with it, because I don't know if the guy who owned it before me did it or not. :)

If the index marks on the cams line up, its WR timing, if they dont, its YZ.


Go to Motomans site here on TT and read up on the tech articles. Good instructions on all the free mods. YZ timing, throttle stop. gray wire etc. Its all there.

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