the engine is stock 49cc, the only modds are the muffler and carb/jet, and i had the ports drilled out. i broke it in with all stock pipe, carb, and ports for all of last summer and this spring.
i was running 50:1 using Valvoline 2-stroke motorcycle oil. but like i said, it looked like i had an air leak from the exhaust port, and also ive had some fuel flow issues, so maybe that affected it too.
anyways, im going to put it back together tonight and put new gas with more oil in it, check for air leaks and cross my fingers.