I was a YAMAHA dealer here in Canada. The QT50 is a great little bike. the brake shoes are very small and wear out but are the same as the MJ50 and the little PW50 that is still made the same for24 years, very easy to get . The muffler can plug up and the motor will hardly run. Also you have to take off the exhaust pipe at the cylinder head and check for carbon in the exhaust port, don't scratch the piston while using a screwdriver to scrape out the carbon. Check the plug gap, must be .018" to .025" because the ignition is weak compared to a car. If I remember the brake springs are made in the shape of a " U " or horse shoe and would never wear out.