I am writing this to help others who are new to the world of motorized bikes. I had problems with my bike slowly losing power and tried all kinds of things to correct the problem. It just kept getting worse. THe problem was with the muffler. The catalytic converter was so clogged the engine couldn't run correctly. With the muffler removed the engine had all kinds of power. So now I think I will take the muffler apart and remove the catalytic converter (sorry Al Gore) because the motor really ran great with the muffler removed. I guess I wanted people to know that a loss of power over time, with nothing seeming to help, indicates that the problem is not in the fuel intake (carb settings, air leaks, etc) but rather with the exhaust. Also, even though the literature that comes with the bike instructs one to use a 16:1 gas to oil mixture, in my opinion this is way too rich and ended up killing my power and causing all kinds of unneeded tinkering. I hope this is a help to someone