I've got one small bite from starting an engine. The real damage has happened when I have put my hand through the arc of a running engine, both times to adjust a needle valve. The first time was while breaking in a Supertiger .45 on my trainer, probably close to 20 years ago. Sliced my index finger something like 13 times from knuckle to tip. It is still not "right". A neighbor kid had come over to see what the noise was about (engine, not me yelling ). I'd been richening/leaning enough times that when I got distracted I just reached through. Second time was while performing a final adjustment on a kid's trainer .40, fortunately at fast idle. Still took months for my thumbnail to grow normally. Very easy to get distracted by others. I use a starter on small engines and a heavy leather glove for hand propping gassers. Always tie down your planes and always have bystanders away for both their safety and yours. I HATE starting big Saitos!