Big Bore Kits

3 replies to this topic
  • rockieman

Posted November 15, 2005 - 09:05 PM


I'm looking at going to a bigger bore for my '99 400 rebuild. The original cylinder appears to be in pretty good shape, the bike has roughly 8500 miles which leads me to believe "it's due".
Anyone have any personal experience with the following?

Others I should consider?
Thanks in advance for your input. :applause:

  • nimiz1

Posted November 15, 2005 - 10:55 PM


Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Indy_WR450

Posted November 16, 2005 - 03:37 AM


I have the Max-Power 490 kit in mine. Very happy with it. Max Power is first class but expensive. I had the engine completely rebuilt last winter and put about 4,000. miles on it since then. Still purrs! :applause:

  • Brettv

Posted November 16, 2005 - 04:27 AM


if i were you, ( i have considered doing this myself) i would upgrade to a 426 cylinder drops right on. and a 426 piston AND rod. boring a 400 bigger has been known to cause premature rod failure. the 426 rods at the piston end were bigger to increase strength. then if you want in the future you could overbore the 426 cylinder to 444cc. or go to powroll for a stroker!
if you get OEM parts from the thumpertalk store, it will work out at a decent price.
i think from memory you would need
426 jug
426 piston
426 rod
426 head gasket and base?
cheers - Brett


Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.