One System I Have Been Thinking Of; The 98 Or 99cc Eng, Sbp 4 Stroke Motor Mount And Their 4 Stroke Jackshaft Bracket. Use A Primary And Secondary Belt. Use A Whizzer Type Rear Sheave. Think How Long A Fan Belt Gives Trouble Free Service.
I Would Prefer Using A Solid Small Pulley On The Crankshaft. Use A Spring Loaded Front Belt Tensioner Pushing Up On The Bottom Of Belt. Use A Latchable Clutch Lever And A Cable To Pull Against The Spring Tensioner, To Loosen Belt For A Clutch. Not Much To Go Wrong In This Type Of System. I Like The Thumb Throttle With The Dual Brake Lever, $12.95 On Ebay Free Shipping. Have That On My Shifter Bike And Would Not Consider Any Twist Throttle Junk!! Imho Lol.
PS I would use 98cc rather than 79cc greyhound, easier to mount with the upright cyclinder. A spring loaded belt tensioner on the rear would be excellent also, never have to adjust belts and you don`t have the tite/loose spots from things not being perfect.
I have two cvt builds. With the 98cc i don`t think a multi speed would be needed. you can change ratio`s by changing one or both jackshaft pulleys
Thats my story and i`m sticking to it!!