I bought my RX 100 in 1986 - sixteen years of Unbelievable performance. Clocked over three lakh km without opening up the engine. Can you believe it - still on original headlamp and tail-lamp bulbs and original brake, clutch and throttle cables. The only things replaced were the ones that wear out - six sets of chain and sprockets, about six front tyres and nine rear tyres. Built like a tank, the rear foot-rests still do not droop (look at old Hondas and Kawasaki and Suzukis).
Mileage - 35 Kmpl, but then you are riding a Yamaha for the torque.
Maintenance - Keep the air filter clean and wet with oil. Change your crank case oil frequently when new till the deposits reduce and battery water level topped - all this you can do yourself and the bike never needs a visit to the dealer - really never.
The six volt electricals is the only thing I am not happy about. At six volts you cannot draw much power for the lights and the horn (the Japs over estimated our public lighting and traffic sense)