Hi Jack,
The early edition 2008 Ambassador had the 70 MM automatic clutch, and I didn't like the motor reving to over 7000 RPMs to travel 40 MPH [the speed limit in my small town is 35 MPH]. So after I encountered a couple of minor "teething" problem with the original clutch, I replaced it with one with different ratios. My Ambassador will now cruise at 40 MPH with the motor turning 5000 RPMs, but it is even slower leaving the stop sign. I was willing to degrade the take off speed in favor of a smooth cruising speed. The stock Ambassador struggles to reach 40 MPH with both the stock clutch or the modified version, it is a matter of torque verses weight. If the load on the motor is stock it will reach 40 MPH at high RPMs, or geared higher [or lower, depending on your outlook on ratios] is will reach 40 MPH at the peak of the torque range. I don't think the Ambassador motor will pull a heavier rider to 40 MPH with the taller gearing I am using, because I only weigh about 165 to 170 lbs. I was hoping the CVT version would have a slightly larger output pulley to take advantage of running the motor at a lower RPM, but guess it didn't happen.

Have fun,
Quenton