What engines are the same?

2 replies to this topic
  • DrBeardface

Posted February 17, 2012 - 07:26 AM


What year WR450 engines are the same? From component part numbers it looks like it's split up between 03, 04-06, and 07-09 or something thereabouts. Can anybody shed some light on this for me? Thanks.

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  • grayracer513

Posted February 17, 2012 - 08:21 AM


'03-'06 WR's are the same basic Gen1 WR/YZ450. A lot of changes were made in '04-'05, but they were all refinements of the same engine, and everything pretty much interchanges.

The '07-'11 WR is the Gen2 engine used in the '06-'09 YZ450's and the bikes had aluminum frames.

The new '12 model is the same Gen2 basic engine with an all new chassis and EFI.

  • BoiseBee

Posted February 17, 2012 - 05:47 PM


The new '12 model is the same Gen2 basic engine with an all new chassis and EFI.

I've got the March issue of Transmoto magazine, and Yamaha's Peter Payne reports that "Contrary to initial response, the engine is considerably different than previous generations of WR-450F's". So this 2012 may indeed be a 3rd generation to the 5 valve motor. He specifically mentions new modified conrod, new bottom end dimensions, new piston assembly, modified crankcase to fit the 250 chassis, relocated oil drain plug, re-designed gear shift forks, modified intake manifold, etc. etc.


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