Valve clearances too big - what's the worst that can happen

ChasF

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I've just been doing the valves on my 530. It's a long story but my local (2hr round trip) KTM dealer supplied the wrong diameter shims. It turns out he'll have to order the correct ones (which are the same for all current KTMs).

As it has taken 2 weeks to get to this stage and it will take another week for the right ones to arrive I tried 'adjusting' the existing shims. I made a simple jig to hold the shim and removed a little material with a belt sander from the valve side of the shim. Trouble is they are not as hard as I thought and even one second in contact with the belt has removed too much. The exhaust ones worked out fine and they are both on the top limit (0.17 mm) but the inlets are both about 0.05/6 mm above the top limit (0.2 instead of 0.15mm).

I've put it all back together and it is running fine. What are the potential problems of having too large a clearance?
 
I don't know what problems it would cause but there's no way in hell I'd run the bike after 'adjusting' the shims like that. Waiting a week for the correct shims is better than a ruined engine in my book.
 
Just got back from a 100km trail ride and the bike is running fine (as it was with slightly tight valve clearances).

I accept that the belt sander was a bit viscious for a first attempt but I wrongly assumed that the shims were very hard. The practice of facing off the shims is common but next time I'll probably use a diamond sharpening stone.

Sunday afternoons are the only time I have for my weekly fix of off road and the bike has been sitting in the workshop for 2 weeks now I wasn't going to miss out this weekend as well
 


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