rotate the engine less1 shim?

[Steve]

No, but neither does any other method, except for putting in a much smaller shim and measuring all the extra clearance.

For that reason, many of us that work on several bikes or even get a "new" one occasionally, will have a "checking" shim that is several sizes smaller.

Most of the bikes left the factory with shims in the 2.70 to 2.85 range, so having a 2.50 on hand would work.
I happen to also have a 2.40, which came in handy because I recently did a valve adjustment on a bike that needed 2.45 shims.

My spreadsheet will handle up to six shim sizes of extra clearance, but since the increment in shim sizes is larger than the minimum clearance, there is no way to tell how "negative" that clearance might be.

.

[oldgsfan]

Steve's spreadsheet is awesome! I used it today, as a matter of fact.

I just measured my clearances this morning. Like you, on a couple i couldn't get my .004 mm gauge to fit in all the way through.

Since I don't have any shims smaller than what I have in there now (2.60), I ordered 2.55 and 2.50 from Z1 - I figure an extra six bucks is just insurance in case I need to go smaller than what I'm guessing.

Btw - the first time I did this valve adjustment on my bike a couple of years ago, I rotated the lobe with a shim out -- didn't know any better and hadn't read enough of the forum - Anyway, it was scary as heck and I spent a while making sure the metal shavings were all cleaned out. Won't do that again!

[JATO]

When I did my shims for the first time, I had to buy a 2.15 shim and start from there on some of my valves. I ended up going through my valves three times the first time around to get them into spec. I started with the 2.15, measured, replaced with the "correct" shim, remeasured, and adjusted from there.