So I've been riding around my new creation for a couple days now (mountain bike w/ 80cc). I thought I tightened the exhaust plenty, and even locktited the nuts on, but burnt black oil is leaking out. I remember I had a 2stroke dirt bike years ago and the exhaust leaked the same way, but a bike mechanic said that it was supposed to do that. Is my 80cc supposed to drip gook out between the engine and the muffler? Or do I need to put on a better seal? Also I smell like gasoline after every ride, but would rather not. Is this inevitable?