I agree with you there Ed. Just giving out some information here from what I've experienced. At first I had my engine with 0.3 mm shim. I noticed that it didn't have punch in the 1st speed but when 2nd speed kicks in, it had loads of power. It was like an off on tap ! I measured my head clearance with the 0.3 mm shim and it was 0.8 mm !

So I took out the 0.3 mm shim and ran it as is. With 0.5 mm head clearance (approx 0.02"), I had to richen the low end a little (about 1 full turn) but power was everywhere ! Engine had a stable idle and it did not overheat. Top end was also excellent.

But then again, doing that gave problems to my conrod. Found that out because the engine felt sluggish after a few tanks. I thought my main bearing was a gonna but it turned out that the conrod bushing was already giving a lot more play than it should. It's the same conrod I used for breaking in and I guess after about 1 gallon or so, it's time to change the conrod. More so after experiencing more compression...