Just bought an 82 CM450 Custom on an impulse. It has about 9k miles and looks great but it misses and lurches, especially at low RMP. When totally cold it starts and runs great while the choke is out. As I push the choke in, it starts to miss a lot. I took it to a Honda Dealership and they cleaned the carburetors but it made very little difference. Anybody seen anything like this?