WR450 valve shims

3 replies to this topic
  • tweek

Posted August 14, 2004 - 02:00 PM


My intake valves were all out of spec. and required different size shims, But the exhaust valves were all in spec. Anybody else have this experience? I had a bad experence with my air filter... did I damage my intake valve seats????

  • YFZRooster

Posted August 14, 2004 - 02:53 PM


You could do some damage but it depends in you valves are too tight or too lose. Too tight will make it run horrible and maybe not at all. Valves could hit the piston. Too lose, you are losing power, especially low end.
I have an entire shim kiy for that bike if you are in the market for one. Pretty hard to come by these days I hear.

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  • twistngrip

Posted August 14, 2004 - 03:56 PM


How far out are they? Mine required one shim replacement on the intake valves after about 50 hours and none on the exhaust valves. They have remained unchanged for the last 150 hours. I would imagine there is no real problem. You probably just need to make the needed adjustments and you will be good to go for a long time. Best of luck.

  • grayracer513

Posted August 15, 2004 - 12:38 PM


Just did my son's 250f and found pretty much the same thing. 2 intakes under spec while both exhausts were at the low end of the range. In most dual overhead cam engines, it is far more likely that valves will loose clearance due to wear at the valve/valve seat than gain clearance due to wear at the cam/cam follower (tappet)/valve stem. Since the exhaust seats are usually harder than the intakes, I don't see that this wear condition is that unexpected.

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