wot sputter

after changing my pipe on my 2000 wr400 to a fmf powercore 4sa and changing the mj from a 165 to a 168 and then backing ou the pilot ait screw to 21/2 turns out per a fmf tech I spoke to, the bike ran great up my street, But after riding it all day today for the first time I noticed that at wot it sputters. Is that due to the jetting or to the fact that I have removed my throttle stop pin (not shave it down but remove it) other than the wot thing it runs great.

Any help would be appreciated



Yes, the problem is that you removed your throttle stop. File the stop down and check to make sure your slide opens up all the way

with it back in. Make sure you don't take too much off though. Erik


So Cal Erik

Visit my club's site at <A HREF="http://www.ruts.org

" TARGET=_blank>www.ruts.org


thanks eric

Eric, when I bought my bike, the throttle stop must have been gone. I haven't notice a hesitation at WOT however; I've only ridden the bike a few times. If I end up with a problem, how do I fix it if I don't have the stop? My understanding is that you cannot buy just the stop. Suggestions?

Bryan -

Check with Sudco or Carb Warehouse. . .when I bought my YZ conversion kit from Baja Designs it came with a "modified" throttle stop. $25 for the kit. Includes conversion directions, PJ, MJ and throttle stop.

www.sudco.com 323-728-5407 www.carbparts.com (216) 524-1599


'00 WR, YZ modified and MX-Tech suspension;now if I could just ride it.


in my opinion the throttle stop is there to help protect the mechanics of the carb from overstrain. it's got nothing to do with the performance of your carb. you are doing ok.

the problem is that the bike is running lean on MJ. JD & CM will clarify, but i would guess that 172-175 should do it.



you could always just order the yz426 throttle stop, part # is 5jg-14591-00.

cost for me was around $8, the dealer probably will have a hard time because I dont think it's shown on the microfiche but tell him to call Yamaha and ask them.

[This message has been edited by Rick Graham (edited 10-20-2000).]

With the pipe and jetting change, the bike may be pulling so hard through the rev range, you could be hitting the rev limiter??

I experienced this when I finally got my jetting correct. The bike just ripped to the top and felt like it wanted to keep pulling.



86TT225, 98CR80, 99WR, WR timing, throttle stop trimmed, air box lid removed, White Bros head pipe, silencer and air filter. Odometer and headlight removed. Moose hand and mud guards. YZ stock tank and IMS seat. Renthal Jimmy Button "highs" and Renthal Soft half waffle grips. AMA, SETRA.

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