yz400f kicks through stroke

I recently discovered i can start my bike w/o the decomp lever, its not easy, but if i jump on it i can get it to go through the stroke. I had the head off 3 rides ago and i did the solvent test on all the valves, and i had to lap one of them a little bit. Once i had the head on and the cams in i checked all the tolerences and they were all on the upper end of the scale.

It runs great, starts first kick, i havent noticed a loss in power or anything, the cylinder, rings and piston were fine. I never tried to start it w/o the decomp until yesterday though.

I can get the front end up sitting down in 5th gear, running 14/49 gearing.

but it scares me that i can kick it through the stroke...

what should i do!?!?

I wouldn't worry about it myself. I had a 99 YZ400 and now have an 02 WR426 and both of them would kick through the stroke if you stood on the lever and bounced a little. I would not advise kicking it this way however, you could create enough pressure to crack the case around the kick shaft. Hope this helps.


Yeah i dont think its anything to worry about, both my dad and my brother have 426's and they can both kick through the stroke if jumping on it hard enough. My dad found this out breaking the decomp lever off in the middle of no where. :ride:

thanks guys,

I love this forum

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