WR450 Engine Differences Throughout the Years

7 replies to this topic
  • jmkybf

Posted June 25, 2009 - 12:33 PM


I have searched on the year to year differences on the WR450, and I have not found much engine wise. I know of the starter key shearing issue in '03 that was resovled in '04. Also I think the head casting may have changed at one point to get rid of the manual decompression hook up. Aside from these small changes, has there been anything that would cause major interchangability issues throughout the years? I know that the YZ's have gone under changes speciffically with the transmission that doesn't make parts interchangable. Thanks in advance for the help.


Posted June 25, 2009 - 12:41 PM


oil storage moved from the frame to the att'd basin in 06'...

  • jmkybf

Posted June 25, 2009 - 04:17 PM


But the +06 is still a complete dry sump, unlike the CRFs that have separated oiling systems?


Posted June 25, 2009 - 06:55 PM


But the +06 is still a complete dry sump, unlike the CRFs that have separated oiling systems?

Yes but there will likely be an "interchangeability issue" if you try to put a 06' or prior motor into a 07' or newer chassis and vice versa to a certain degree...

There's differences in the left side case cover to on the 07' and newer... I think it's quite bit different than earlier models.????

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  • jmkybf

Posted June 26, 2009 - 07:08 AM


The project is a college Formula SAE Race Car. For more info on our team you can go to http://fsae.mst.edu/

What I am trying to do now is gather some information on changablility issues purely related to engine internals and cases through out the years. We have been running a Yamaha R6 engine in the years past, but the series requires us to be restricted to a 20mm air inlet, so we are looking to change over to a smaller engine for the simplicity and lighter weight. We do all of our own custom fuel injection and exhaust, and in this case, oil resivoir. I am more familar with Wr's since I have a WR400, but we have to have electric start, so we are looking at WR450, CRF450X, and possible KTM450 or 525.

  • screamingjimmy

Posted June 26, 2009 - 08:14 AM


i believe compression dropped from 12.5 to 12.3 in 2005 or 2006.

  • Icelandic_amateur

Posted July 16, 2009 - 03:06 AM


2003 and 2004 has compression ratio of 12.5 / 1
but the 2005 (and I think onwards) had it 12.3 / 1 to try to smooth out the power.

A friend of mine has a 2003 WR 450, I have 2005. We haven't tried each others bikes yet, but I can confirm that he complains a lot that his bike is lacking torque (compared to his Honda XR 600 1997 model), but I find mine just perfect.

  • Icelandic_amateur

Posted July 16, 2009 - 03:07 AM


One more thing: You can read about the changes they made on the 2005 bike here:


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