2003 Yamaha Motorsports Road Star Owners Manual - Page 65
2003 Yamaha Motorsports Road Star Manual
Page 65 highlights
PERIODIC MAINTENANCE AND MINOR REPAIR The porcelain insulator around the center electrode of each spark plug should be a medium-to-light tan (the ideal color when the motorcycle is ridden normally), and all spark plugs installed in the engine should have the same color. If any spark plug shows a distinctly different color, the engine could be defective. Do not attempt to diagnose such problems yourself. Instead, have a Yamaha dealer check the motorcycle. If a spark plug shows signs of electrode erosion and excessive carbon or other deposits, it should be replaced. Specified spark plug: DPR7EA-9/NGK or X22EPR-U9/DENSO Before installing a spark plug, the spark plug gap should be measured with a wire thickness gauge and, if necessary, adjusted to specification. Spark plug gap: 0.03-0.04 in (0.8-0.9 mm) 6-8 Clean the surface of the spark plug gasket and its mating surface, and then wipe off any grime from the spark plug threads. Tightening torque: Spark plug: 12.5 ft·lbf (1.75 m·kgf, 17.5 Nm) NOTE: If a torque wrench is not available when installing a spark plug, a good estimate of the correct torque is 1/4-1/2 turn past finger tight. However, the spark plug should be tightened to the specified torque as soon as possible. @ @ a. Spark plug gap EAU01639 Checking the spark plugs The spark plugs are important engine components, which should be checked periodically, preferably by a Yamaha dealer. Since heat and deposits will cause any spark plug to slowly erode, they should be removed and checked in accordance with the periodic maintenance and lubrication chart. In addition, the condition of the spark plugs can reveal the condition of the engine. 6