Re: 45mph at ~7600rpms
I haven't ever bothered to run a tach. I have always run an accurate electronic speedo though. I always mathematically calculate my speed to rpm, and after that I know my rpm by what speed I'm going. That's easy to do when you only have 1 gear.
Sometimes I run my motor over 7000 rpm, but I like to keep it a little under 7000. I've found that if you cruise over 7000 very much it really shortens the life of your motor. Above 7500 really is pushing it. At 8500 it could blow at any time.