The China-Girl engine in my bike is very reliable with common aftermarket parts installed: Rock Solid Engines reed Valve Intake, Jaguar CDI, Dellorto carburettor jet, SickBikeParts Air Filter, SickBikeParts spark plug lead and a centrifugal clutch.
The other items are just plain nice to have: pull-start mechanism, Koso Exhaust Gas Temperature gauge, TTO Cylinder Head Temperature gauge, tacho and chain tensioners; chain guides (fixed and roller), front derailleur operated multi-sprocket-stack bottom bracket chain rings, front and rear lights, fuel bottles, gel seat and suspension seat pole, air horn, mirrors and indicators, brake light, mud guards, centre stand, and of course the Pièce de résistance: a heavy haulage trailer train comprising 6 trailers and a BoB IBEX uni-wheel trailer for expeditionary adventures...
Now where were we with your friction drive assembly: dry surfaces only,,, no water, no sand, no mud, no gravel, no creek crossings, no filthy dirty; snotty steep hill climbs, no heavy haulage, no far and away adventures with any of the above!