2002 Yamaha Motorsports VK 540 lll Owners Manual - Page 45

ESU00141 TOOL KIT The owner's tool kit has the tools which are sufficient for most periodic maintenance and minor repair. A torque wrench is also necessary to properly tighten nuts and bolts. 1 Tool kit 846-006 NOTE: If you do not have a torque wrench available during a service operation requiring one, take your machine to a Yamaha dealer to check the torque settings and adjust them if necessary. ESU00144 SPARK PLUG INSPECTION The spark plug is an important engine component and is easy to inspect. The condition of the spark plug can indicate something of the condition of the engine. Check the coloration on the white porcelain insulator around the center electrode. The ideal coloration at this point is a medium to a light tan color for a machine that is being ridden normally. If a spark plug shows a distinctly different color, there could be something wrong with the engine. For example, a very white center electrode porcelain color could indicate an intake track air leak or carburetion problem for that cylinder. Do not attempt to diagnose such problems yourself. Instead, take the machine to your Yamaha dealer. You should periodically remove and inspect the spark plug because heat and deposits will cause any spark plug to slowly break down and erode. Consult your dealer before changing to a different type of spark plug. Standard spark plug: BR9ES (NGK) Spark plugs are produced in several different thread lengths. The thread length (reach) is the distance from the spark plug gasket seat to the end of the threaded portion. If the reach is too long, overheating and engine damage may result. If the reach is too short, spark plug fouling and poor performance may result. Also, if too short, carbon will form on the exposed threads resulting in combustion 8-4