Hi wrenching4fun. That's a good question because it reminded me of my EZ Motorbike Co. Q-matic motorized bicycle transmission. The builder put the maxtorque clutch on the output shaft of his jackshaft transmission because the engine will spin up faster with less weight on the crankshaft. He also said that the clutch vibrates less when placed on the output shaft. My Q-matic has a reduction ratio of 2.7 : 1. The clutch engages at 1000rpm therefore, when the engine turns at 2700rpm the clutch will spin at 1000rpm and will engage. The reduction ratio within the transmiission is easy to change from about 2.3 : 1 down to 3.5 : 1 with a change of the crankshaft pulley depending upon the size and maximum rpm of the engine you're fitting the transmission to. I have this transmission on Hausheng 49cc and HF 79cc 4 stroke engines and it works very well for many years.