Removing the throttle stop?

I just bought a new WR426F today. Could someone tell about the "free" power upgrades? I know about removing the airbox lid. How do you remove the throttle stop? And what about the exhaust? What can I do with the stock exhaust to make it better?


You don't want to remove the throttle stop, just grind it down about 18mm. As for the exhaust, pull out the innards "uncorking" it, and then buy a promoto billet endcap and spark arrestor so your are legal and less noisy. I think you can search this site for the other free mods including the gray wire and such.

Good Luck :)

Go to MotoMan393's page on the home page of TT, there you will find instructions on the BK/GB mod', YZ timing mod' etc. Most important mod's initially will involve getting it to breathe by removing the airbox lid and opening up the exhaust which you have already mentioned. A YZ muffler bolts straight on, though may be too noisy for where you ride? Re-jetting will probably be necessary after the mod's. HTH :)


head over to the WR/YZ250F FAQ, there are a lot of hints and tips there that are also applicable to your WR426F as well.

at the least you can use the pictures there to figure out where the throttle stop is.

also see my page here:

note that the 250F and 426F probably have different throttle stop lengths -- but you can figure out how long yours needs to be by looking at the slide open through the carb intake.

jim aka the wrooster

'01 wr250f

Or just buy the YZ stop from dealer, it's cheap, and it's the right length.

Thanks guys, you have been a lot of help!

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