Neophyte questions to be sure. While flying yesterday, I noticed that the exhaust residue was darker that it had been previously. It seems that the engine has now completed the break-in phase as it can now be leaned and hold its setting. The power increase was also impressive. The question is whether this exhaust color is indicative of an over compressed engine, or if this is just about right. The engine did not sound labored.

Also, when I was attempting to remove the anodized portioned of the head (where the compression screw is located) the entire cylinder came off. No big worries there, but looking at the piston, I noticed a fair amount of carbon build up. Is this normal? Like the above question, does this indicate an over compressed engine, or is it a byproduct of burning kerosene?

Thanks - as always - for your time.