Cylinder uppgrade

2 replies to this topic
  • Oxen

Posted September 25, 2004 - 07:49 AM


I want uppgrade my YZ400F 1998 to 450cc or 500cc.
Does anyone knows if thats possible?
Which company sells the cylinder?
Can i fit a 426 cylinder on my bike?


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  • hontrx265r

Posted September 27, 2004 - 02:53 AM


Its alot of work and a fair amount of cash but you can use a 426 cylinder with a 2mm overbore and a 2mm stroker I recommend powroll, this will bump you up to a 467 some where in there I forget, but its killer not all that reliable though.
You could probably get a 426 cylinder that is overbored for cheap from one of the quad guys makes it a 440 I bought mine for 100.00 bucks put a post on

  • Rich_Rohrich

Posted September 27, 2004 - 09:34 AM


I want uppgrade my YZ400F 1998 to 450cc or 500cc.
Does anyone knows if thats possible?

You can use a 2mm overbored 426 barrel and 97mm piston (Wiseco or JE) to get 444cc. You will need to rebuild the crank with a 426 rod to accomplish this due to the larger wrist pin on the 444cc piston. Rebuilding the crank with the 426 is a good idea in general on these old 400 motors. The rod was the biggest weakness in an otherwise fantastic motor.

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