to me the scooter transmission IS the belt-pully variator, like in the changzuki.
http://ecomodder.com/forum/showthrea...tml#post244431 , I believe that is the "comet" transmission there.
The appeal of the variator with a diesel motorcycle conversion is clear, they are readily available and not too expensive and there are plenty of working examples. But I have been researching suitable gearboxes as well, and personally would rather go through the effort to have a clutch and gears. I can get over 100mpg on my 250 without the conversion (and with plenty of available acceleration and top speed), I have to aim a lot higher than 104MPG to make it worth the effort for me, and I think gears would help, but it is a notably more challenging path at current and not for everyone.