Hi Terry,
I wonder if the primary drive ratios are the 4 X 1 instead of the 5 X 1. If it is 4 X 1 then it would be possible to reach the speeds without putting the motor into orbit. I know when Don first contacted me he had the numbers all wrong and was adding the primary & secondary ratios instead of multiplying them. I guess they do math differently in China ["NCM" new Chinese math LOL].
If you are using a 50 rear divided by 11 then the ratio is 4.54 X 1 and if using American math and multiplying the final would be 18.18 X 1 [if the front is 4 X 1]. At 30 MPH on a 24" the motor would be turning 7650.
One of the reasons we elected to offer different ratios on our drive was to stop from running the motor at such high RPMs at normal cruising speeds.
The majority of our customers only want to cruise at 30 MPH to 35 MPH, get good mileage and have plently of power to avoid pedal assist at take off. If the drives are made with very high ratios [22.7 X 1], the take off is great, but the motor is wound tight at crusing speeds and the gas mileage drops like a rock. Not to mention constant high RPM speeds isn't good for motor life.
Looks like the ratios needed on the 2-stroke motors was carried over to the 4-stroke motors and noone made the needed changes to work correctly. 2-stroke motors have very little torque at low RPMs and need wild ratios to work, whereas 4-stroke motors have lots more torque at lower RPMs and don't need the same ratios to get the bike in motion.
We spent a lot of time, money & research in arriving at good basic ratios for the 49 CC 4-stroke motors and understood the need for different ratios for different conditions. Some want to fly, some want to cruise, some need to climb hills, and some gained a little weight, and those are the reasons we made the drives easily "tuneable".
Have fun,
