The 40mm carburetor can get cranky over time, making the engine hard to start when hot. It makes the engine more conducive to hot-rodding, but only by a well-informed wrench. Any bike with an aftermarket exhaust and jet kit deserves an even closer look. A good detergent gasoline and/or fuel additive-Yamaha Ring Free or Chevron Techron Fuel System Cleaner, for example-can keep carbon from building up on the valves, especially in an '04. If you'd rather not deal with a carburetor at all, find a nice clean fuel-injected '08 model.