Well, I got my little QT50 all cleaned up and ready to go, put a new air filter on it, and it'll crank and run like a champ...but...only if I keep my hand over the carb opening. Won't run like anything otherwise.
My first suspect was a clogged exhaust system, but once I pulled it off, it looked OK. Obligatory crud, but nothing obstructed.
Next stop: cylinder head. So I pull it off, and the inside of the cylinder has a couple of minor-looking scratches running the length of the inside cylinder wall on the bottom.
Its not terribly worn, mind you, but there are fine scratches in there.
Are a few relatively benign-looking abrasions inside the little 50cc's cylinder enough to compromise its compression? Also, if I have this thing machined, where in the world do you find over-sized piston rings for a 23 year old 2-stroke motor?