Easy midrange flatspot fix

Like the rest of you, I aspire to things that make my bikes run better: On the WR426/250. There is a flat spot after 1/2 to 3/4 throddle. To fix this w/o all the rejetting discussion that fills this site up, try this simple fix.

Under the gas tank there is a black connector with 2 wires going into it. 1-solid grey/1-black & grey.

Disconnect the solid grey wire, seal up connections with Elect.tape or silicon. This wire is for a rev limitor that Yamaha has,to pass emissions. The other wire is the kill button. This should clean up a lot of the trouble owners are having with flatspots, jetting fixes that have no effect, etc....

This fix came from a source that spends a lot of time testing/racing for big blue. Hope this helps......

Sounds great, but there's no way I'm personally unhooking the rev limiter. As fast as this beast spins to redline, I'll overrev it the first ride. The factory has big $$$ to spend, we all don't.

Also, I don't seem to have a flatspot. With YZ timing and good jetting, it revs so darn fast the midrange only lasts 1/2 second!


help me understand something -- how does toying with the rev limiter change the behaviour of the engine in the midrange (which by definition is below the engine's rev limit, some would say it's around 1/2 of the rev limit)?


the wrooster

'01 wr250f

I'm with mcarp, I would leave it alone. Get stupid, overrev the motor and float a valve just once and after having to dump at least a grand into a wasted motor you'll sit there and cry "oh why was I so stupid?!" I personally don't feel this illusive flat spot either though. Just my .02 worth :)


'00 WR 400




[This message has been edited by Russ P (edited 06-06-2001).]

Russ P there is a chance on the 1998/1999/2000 WR400 that this may not be a issue. We are still working on this....

This fix is working on 2001WR250s from the WR/YZ250 post under "Whats wrong with the WRs"

Has anyone attempted to remove/disconnect the grey wire on a 2001 WR426 yet?????What results have been found??????.

I believe that this should clean up a lot of problems people are having with "Patchy Midrange issues", that jetting does not cure.

Also, there is a reason the non-US spec WR's don't have this issue --- they do not have the emission restrictions we do. That is why this grey wire is only applicable for US spec bikes. I do not think that any damage will occur - by disconnecting this wire. Why?

Because the non-US spec bikes do not have this & they are not floating Valves or blowing up.....

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now