I am curious about thing regarding the shimming of cylinders, and that is the fact none of the experts have even mentioned the effect it has on port timing. I know from my experience racing dirt squirts and mini hydro's how little change it takes in the timing to make a noticable difference. Port size and shape also have an impact on performance characteristics too, yet again, through this whole thread and others I have read, not one of these points have been raised. This reminds me of the dys when all us 'hoons' were souping up our V8's, everyone was worried about what cam and which holley carby the were running, with little attention to the rest of the motor. As with any motor, you build ait up from the bottom, good crank, topline bearings, and go from there.
Whhat brought me back here ( I have had health issues stoppin me flying my planes) was a good mate ploughed his extra in last weekend, and we took the motor out (DLA 112), and stripped it, and checked it right out. What surprised us both was the crank only got bent about .018", and the carby got a gutful of mud. This motor has had approx 30L fuel thru it and ran like a swiss clock and a new crank has been ordered. The internals all looked good, bearing were clean, well lubed, no slop or play anywhere, so it ill be getting a new airframe in the very near future. As far as quality of castings go, they were definately not inferior. All up, whn I get back into flying I will seriously be looking at a few DLA motors for various projects