Hi,I bought my wife an 83 Maxim. Its about the right size for her and she enjoys riding it. I took it to work the other day and noticed though that at 50 MPH the motor is screaming at 5000 RPM and I was worried it was gonna blow up! The bike is a 5 speed. Is this the top speed on this bike due to the gearing or is there some carb problem? Any ideas?