Stock shim size on an 07 WR450F


New to these forums not to sure if this topic has been covered. I have just removed cams and and all other bits and pieces to change an exhaust valve spring as the clearance on it had no clear reading and a mechanic told me it would be a weak valve spring. But as i removed the valve lifter i was surprised and pissed to find NO SHIM! the rest were all good but the bike has had starting problems ever since its rebuild after it threw a bottem end. anyway does anyone have any idea of what came out standard in this model just so i have a starting point to measure from or do i just guess and work my way through the shim kit till the clearance is right?

Thanks in advance, Nick

Nick, Quite often the shim will stick to the underside of the bucket. Are you sure this isn't where your shim is? And there is no "stock" shim size, each and every valve has whatever shim size it takes to bring the clearance into spec. Hope this helps.

Can you elaborate on the need to change the spring again as well? What you're saying, and what the dealer said isn't making sense to me....not sure what clearance is marked on a valve spring and how that makes it weak.

Now, if you truly have no shim on that valve, you'll have all kinds of starting issues, I'd imagine. But if I remember my bike correctly, all shims were in the ballpark so measure one of your other ones and start there. Or just use one for your measuring.

Edited by miweber929

thanks for the replies,

First about the spring what i meant was when i was trying to measure the clearance i wasnt getting a convicing reading as the gap kept increasing with little increase in tension on the feeler gauge, So i went to my local mechanic (not a motrobike shop as the nearest one from me is 850km away) and asked him about valves and clearances and he told me sounds like a weak valve spring so i went with it. At this stage though i had not removed the cams to check the state of the spring i just ordered a new one as it was only $4. Once i recieved it i pulled the cams out and removed the valve lifter and realized there was no shim (and i checked the underside of the bucket Maniac thats about the time i got really upset). Anyway hope that clears that up and all i did was measure the other exhaust shim and used the same one and ill go from there. And just for laughs while i was starting to put it all back together i got my cam chain jammed and is now damaged so after all that now i need a new chain haha!

Thanks guys much appreciated, Nick

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