2003 WR450 Valve Inspection 3,000 Miles

I just helped my Brother check the valves on his 2003 WR450F...

I got these specs from a post on here - Are they correct?

Intake: .004" - .006"

Exhaust: .008" - .010"


Intake 1: .004 Exactly

Intake 2: .0035 (In Between .003 & .004)

Intake 3: .0035 (In Between .003 & .004)

Exhaust 1: .008 Exactly

Exhaust 2: .008 Exactly

SO - Do I need to reshim Intake 2 & Intake 3???

Is is CRUCIAL or is it OKAY?


Its Crucial to keep the valves in spec.


I would reshim if it were mine.

Yes do them all to the high side or even .001" over the max clearance. :)

Thanks - I'll tell my brother we need to reshim - are you SURE .001" OVER the specs, or just .006 and .010

Dont go over unless you cant shim it close to the upper tolerance. :)

We discussed it, and we are going to shim ALL the valves to the MIDDLE of the specs..

Intake: .005

Exhaust .009

I don't forsee them tightening up any more, and if they do, I'll just reshim it to the middle again in a year or so...

Sound Right?

I went to the high side when I first did my valves and noticed lifter tap when the motor was up to temp. I now have them at .006 on intake and .008 on exhaust with no noise. :)

Why would you put the intake at MAX spec, and Exhaust at MIN - is there ANY advantage, or just the "Tap,Tap,Tap"

In the Jan 05 issue of Dirt Bike Magazine pg. 51, there is a description of the set-up on the Glenn Helen 24-hour winning YZ450 of Ty Davis. It mentions that the valve clearances are "set a thousandth looser than normal". I assume this is done for reliability. I have no idea what "normal" means in this context. But FWIW, I always set mine to max specified clearance and have had good results over more than 5000 miles on my 03 Wr450.

That said, I think if you check your valves regularly, and run the clearances in the middle of the spec there should be no problems.

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