Changed shims, same clearance, wtf?

[007brendan]

So I check my exhaust valve clearances, and both are around .03mm.  They have 2.70 shims, but they measure more to be 2.69. I switch the shims out with 2.60 and the clearance is the same.  WTF?!  Is it possible they're not seating correctly?  I spun the engine a few times, but still the same reading.

[Twotogo]

            either they were WAAY too tight to start with and the seats were resting on carbon, ...or one of your other assumptions is incorrect..how'd it run to start with?

[007brendan]

The bike hasn't been idling as well as it used to.  It used to warm up in a couple minutes and would idle without the choke.  The past few months it would take longer to warm up and would stall at lights.  If I set the idle high enough that it wouldn't stall, by the time it was fully warmed up it would be idling at 2500 rpm.

[Twotogo]

glad you're checking the clearances..,common to Not address the engine First. ...ever checked them before?....thinking you need to spin the motor through with the plugs out for 30 seconds to decarbon the seats and then try thinner shim...once the clearance is right your warmup and stalling probs will go away.

[tmbr_wulf]

When you say that they were around .03 mm were you actually able to get a .03 mm feeler in there or are you estimating that it was .03 mm?

[Kerry]

Good point.

I remember adjusting the valves on my old '96 after it had switched owners. In the end, we dropped one of the exhaust shims by 4 sizes! During the process, I noticed that I could "force" different-thickness feelers between the shim and the cam lobe with about the same amount of effort, and almost without noticing that I was forcing them in the first place.  The trick was to figure out the difference in how it feels to "force" a feeler into the gap versus allowing the feeler to stop when it's too thick.

For what it's worth.... 

[007brendan]

When you say that they were around .03 mm were you actually able to get a .03 mm feeler in there or are you estimating that it was .03 mm?

Smallest size i had was .0015in (.038mm).  It fit under one exhaust.  Couldnt fit it on the other bit I could spin the bucket. I dropped the one down another size to 2.60 and now its good (.004in).  Ordered some more shims since I have nothing smaller than 2.60

[gsJack]

Makes sense now, the one you couldn't get the .0015" feeler in could have been .0001" and the bucket would spin.  You probably need a 250 now but it never hurts to get several smaller ones on hand.  Exhaust valve shims only get smaller.