Check this site out. It has bore and stroke kits for many makes and models of ATV.

I knew about a few for Honda and Yamaha but did not know Polaris had any available stroker kits.

Look under "Engine Products" They just list Sportsman,I think the 425,455 and 500 are all the same motor with just a different bore and stroke ,so these kits may work for all of them.

 

Hey TLC,

Yea I remember that huge write up in Dirt Wheels mag, I think that Mudzilla machine
is like valued at 30k. It is running on a Kaw Brute Force 750 with re-engineered parts
and mods, many after market parts.

I didn't see anywhere on the Big Bore thing for the Sportmans if it was a 400,450, or 500 engine?
And a little unclear what you get for that price? Is that to say they take your stock engine of
one of the above listed cc's and border it out to a 600/628cc stroke?

Regards,

R'