HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
YZR426

Old Question, new answers?

6 posts in this topic

#1.

I want to change from the original '01 426cc to a 450cc big bore kit eng. Has anybody played with this size and what did you find, reliability, quik rpm's or slower , torque range ? (if so what manufacturer)

#2.

Has anybody used race cams and larger valves with the big bore kit as well.

#3.

What about ceramic coating of the internals (pistons and valves?)

Thanks in advance for your replies.

BTW you've probably guessed that I'm chasing some more serious HP :)

Share this post


Link to post
Share on other sites

I went 3mm oversize which works out to 453cc.

The stock bike was making 45hp, the big bore brought it up to just under 50hp. Gas flow, big valves, and cam timing has got me to 52.5

It makes more power than stock everywhere, but flattens out between 7k & 10k rpm. The oversize inlet valves made a couple of hp through the mid-range.

Reliability hasn't been a problem so far, but I'm being pretty anal about rod changes (20 hours max). I'm looking at high-lift cams to help it breath above 7k..

Cheers, JonE.

Share this post


Link to post
Share on other sites

im jelous of u guys that u need more power then the stock yz426f n i hope u will use it....

Share this post


Link to post
Share on other sites

LOL! My YZF is a Supermoto(SuperTT) machine. Haven't braved a MX race on it since it was stock - I'm quicker in the dirt on my YZ125!! :)

Share this post


Link to post
Share on other sites

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
Sign in to follow this  
Followers 0