I bought my 1st cycle a 1979 suzuki 750, but when I ride it oil leaks onto the exhaust pipes and it smokes. It appears that the oil is coming from the exhaust port or around the port. When I take off the exhaust pipe and run the bike, I hear a popping noise and little blue flames come out of the exhaust port every once in awhile. I get good cyllinder compression and the plugs fire. Any ideas on how to stop the oil leak?