YZ timed WR426

i know how old this topic is getting, but just wanted to know how much difference it makes to the 426. They are pretty damn strong standard and was concerned that the YZ timing would give it too much of an agressive hit for the woods. Has anyone done it to their WR and what's the verdict?


The only issue seems w/ carburation. A few guys seem to have problems, but many do like it.

One thing you may want to look at is to gear down your bike, depending on your riding areas. I went down one tooth on the countershaft, while others go up two teeth on the rear sprocket. For tighter woods riding, I think it is a very good change.



'99 WZ/YR (you choose!) with ALL YZ mods, de-octopused, DSP Doug Henry airbox w/ velocity stack, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, OEM YZ tank, IMS YZ seat.

For the 400, the change was great for woods riding. Much easier to loft the front end over roots/rocks/trees. Gear down accordingly! More midrange and more top end. I'm able to wind the gear out a little longer before the next turn. Low end power does not seem to be affected, IMHO. With a good pipe, low end will increase!

Sure the 426 has a little more oomph, so I would expect a YZ timed 426 to offer greater performance than a 400. In fact, I would think it would be almost perfect for off-road. Perhaps very tight single track WR timing may be better.

Jetting is important, too. Are you running the optimal mixture now?

There's a little less engine braking, but it's not hard to get used to it. I ride 80% trails--I'll never go back to WR timing.

I would say try it-you can always change it back. Use one of James Dean's jetting recommendations for YZ timing. Total cost would be around $30 for a needle, main jet, pilot, and main air jet.

thankyou kindly for the info. i will give it a try in my friends bike, he's quite heavy so a bit more go might be good for him.

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