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rexbond007

Valves adjustment needed?

6 posts in this topic

07 450 and 12 hrs on it.

This is my first 450.

I checked my valves tonight, as i read a post of one fellow thumper had a tight exhaust valve. Well i was suprized to find all five valves on the tight spec side.

I was under the impression yamaha shims the valves in the middle from factory.

I have always shimmed my 250's on the high spec end. to max hp and as valves always tighten on 250's

both exhaust valves are currently 20 mm and the three intake @ 10.2 mm.

My question to all and Grayracer, will the valves loosen up on the 450 as the bike gets more hrs on it? and just leave it on the tight side for a few more hrs. Or put them into the middle/higher end of spec now.

Right now the bike starts fine.

thanx Rex

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I was under the impression yamaha shims the valves in the middle from factory.

Every one I've ever checked at low hours was built to the tight edge of the spec range. If it's in spec, it's in. Don't worry about it.

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Every one I've ever checked at low hours was built to the tight edge of the spec range. If it's in spec, it's in. Don't worry about it.

O.K.

They must do that for a reason.

since your Older & YZer I'll leave it alone.

thanks

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They must do that for a reason.

Less impact on the valve gear as the valves are opened, and optimized valve lift. Then, too, the whole range from tight to loose is only .002".

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Right now the bike starts fine.

You said it all right there.

My specs were pretty much the same as yours. GrayRacer knows his shtuff!Write your specs down for comparison later. You should be fine.

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My specs were pretty much the same as yours. GrayRacer knows his shtuff!Write your specs down for comparison later. You should be fine.

nice to to know other new bikes have the same valve specs from factory..

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