High Comp piston, Big bore or both?????

2 replies to this topic
  • ca412686

Posted June 15, 2005 - 11:30 AM


Hey guys. I got a 02 YZ426 in SM trim. Im racing at a road race track and I seen to need a bit more power. I can pull away from the guys in the turns and even have a better drive off the corners only to have them catch me on every straight. The other bikes are 450's with motor work done as well. All i really have done to my bike is the standard free mods and a full exhaust system. Im planning on doing the motor after the next round and trying to figure out what would be a better way to go. High comp piston, Big bore, or maybe even both? Im wondering if anyone has done this before and if it would be at all reliable for running on a road course at higher RPM's most of the time. Any help would be great. thanks guys!

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  • djbiker

Posted June 15, 2005 - 11:44 AM


it depends how far you bore out, you'd be find for realibility and durability with just a hi comp piston and maby a 440 bore kit (but you still run the risk of over heating you may want larger ratiotors too.
http://www.powroll.c...A_YZFWR426F.htm :) :)

  • 642MX

Posted June 15, 2005 - 12:44 PM


I've got the Wiseco 13.5:1 piston in my 426. It adds a nice punch right off idle and through the mid range. I don't notice much more power on topend, but I've been pleased with the added compression.

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