On my 40 pound bike I weigh 140 pounds and for top speed with level ground I can hit 30 MPH. With all the original parts that came from the motor kit I bought from Dax. Which is on my 26 Raleigh bike. My torque is good to but not strong enough for a wheele.
I'll just say that I'm heavy enough that I should be riding my bike that does not have an engine and sell the one that does. Don't worry about weight, Sherry, these little engines seem to be able to handle it with relative ease.....I had a guy stop by my shop the other day who musta scaled around 350 and he really seemed interested in my bike. I let him go for a spin and he came back beaming saying that he had the speedo showing over 30mph while climbing a very slight grade.
the motor & bike I bought it in phoenix from a guy that couldn't get it to run ...it was new I thinl he got it from spookie tooth not 100% on that.
the motor was a "80" but when i did the rebuild it mic at 68cc
around 250 miles on the motor I rebuilt it with some honda 70 parts and that was a long time ago .....btw...I'm just about to turn 9000 miles.
and yes I do notice some small loss on the lower end now but its time to get a new jug sized up to fit her ...maybe a new head too