I own a hero puch since Oct 96 and rode more than one lakh kilometers on original engine and did not touch the engine till date except that being two gear vehicles now and then the gear wires brake and can be replaced very easily.
People may not believe if I say that even today the vehicle is running on clutch plates came with new vehicle except that one part in clutch is breaking very often as the original hero puch parts are not available in Hyderabad Andhra Pradesh. Though I have four more two wheelers Hero hond SS, LML. Rajdoot 68 and 72. I prefer heropuch in city traffic as the moped is very light and comfortable for one and can easily go upto 40.