Yz400f " 0.50 " over

4 replies to this topic
  • slideways98

Posted July 06, 2013 - 06:30 AM


I bought a 1999 yz400f for flattrack racing , I was told it was 0.50 over , what would that make it displacement wise , and it has a 19x 1.85 wheel , will a 19.2.15 with a wide flattrack tire fit back there . Thanks for the help .

  • SAthump

Posted July 06, 2013 - 06:46 AM


It shouldn't be anything over its a plated cylinder ???

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Posted July 06, 2013 - 07:23 AM


It shouldn't be anything over its a plated cylinder ???

My 426 has been bored out to a 444 and replated but I have no idea what a .50 over 400 would be.

  • slideways98

Posted July 06, 2013 - 07:39 AM


I might want to get this checked out then , it runs like a raped ape though , do I dare even mess with it ? It's a pain to start I know that ,

  • grayracer513

Posted July 07, 2013 - 06:21 AM


There is no ".50 over", since the only size pistons offered are standard. When worn, the cylinder is either simply replaced, or it's honed out, any damage repaired by welding, if necessary, and then replated and honed back to standard size. The only oversizes are big bore kits that are generally 3mm oversize, not .50.

The 400 is 92x60.1, so .50mm over would be 403cc. Insignificant.

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