A few basic rules of power-washing apply to all types of motorcycles and the most important of them all is to avoid sticking the full force of the spray nozzle at any seals, particularly those around your countershaft, wheel bearings, and electronics. Keeping the spray wand a good 2 to 3 feet away from the bike will reduce the chance of blasting off your graphics, roosting yourself in the face, or damaging valuable hardware over time. Always plug the exhaust, especially on a high-swept style commonly associated with dirt bikes. Over time you can cause rust or corrosion to form in the exhaust system if you clean it and store it right away between rides. The long-term issues of blasting around seals is that you can force particles of dirt along with water between the seal and shaft which can result in premature seal failure.