1999 WR400 cylinedr head help

4 replies to this topic
  • hardrider

Posted July 26, 2005 - 04:42 PM


A friend of mine just picked up a 1999 WR400 with a damaged cylinder head. He needs a replacement. Would 1998 or 2000 cylinder head fit? I notice slightly different part numbers for all 3years. Are they just superceding part numbers? Please help! :applause:


Posted July 31, 2005 - 01:28 AM


Im lookin after my mate's 00' wr 00 at home and the head in it looks identical to my 99wr400's head. In fact the engines look so alike i could swap engines and he wouldnt know the difference (i wouldnt though cause i aint slack !) :D

I dont know the actual differences in the cylinder heads themselves, thats if there is any like porting etc.....

look round in the forums and u should find something on the two types :D

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  • MattyH

Posted August 05, 2005 - 05:51 AM


the cylinder head casting only experienced minor changes in the steps from 400-426-450, the casting only lost the fore and aft bolts and the manual decomp was plugged off (the casting for the manual decomp is still present on my 450 head).

the difference between the different year models of the 400 head i imagine as you suspect are simply superceding part numbers. the valve dimensions, and lengths are unchanged between the years to the best of my knowledge. It would still pay to compare as best you can by sight the external bolt locations between the heads of all 3 years that are in question in case there have been other changes.

  • PumpkinHumper

Posted August 05, 2005 - 10:24 AM


If you can get the head to the states www.enginedynamics.com can probaby fix it way cheeper than a new head depending on whats wrong with it. They salvaged my head on my yz400 when I thought it was junk.


Posted August 05, 2005 - 07:42 PM


I currently have a 98' YZ400F that has a 00' WR head on it. I did alot of research on this and found that 98' and 99' YZ and WR heads are identical. In 00' the only difference that I can find is that the hot start valve was eliminated. The boss where it used to be is still there. I just drilled a hole to press fit the barb that is a standard OEM part. Worked like a dream. Let me know if you need the part number. I have a spare. :D


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