Although all of my Magnum and ASP engines run well a few have metallurgy issues. A couple have soft aluminum castings with cracked carb throats where the carb is inserted into the case. On another the needle valve broke off when closing it, it didn't take much, I figure the metal was too hard. The only engines with issues are a couple of old Fox's with broke mufflers, and one with a bad carb. I had an issue with an OS I used to own, bad bearings. No issues with others except from crash's or just plain worn out.