2006 Yamaha Motorsports Grizzly 660 Auto. 4x4 SE Owners Manual - Page 147
2006 Yamaha Motorsports Grizzly 660 Auto. 4x4 SE Manual
Page 147 highlights
Inspection The spark plug is an important engine component and is easy to inspect. The condition of the spark plug can indicate the condition of the engine. The ideal color on the white insulator around the center electrode is a mediumto-light tan color for a ATV that is being ridden normally. Do not attempt to diagnose such problems yourself. Instead, take the ATV to a Yamaha dealer. You should periodically remove and inspect the spark plug because heat and deposits will cause the spark plug to slowly break down and erode. If electrode erosion becomes excessive, or if carbon and other deposits are excessive, you should replace the spark plug with the specified plug. Specified spark plug: DPR8EA-9 (NGK) Installation 1. Measure the electrode gap with a wire thickness gauge and, if necessary, adjust the gap to specification. Spark plug gap: 0.8-0.9 mm (0.031-0.035 in) a. Spark plug gap 2. Clean the gasket surface. Wipe off any grime from the threads. 3. Install the spark plug and tighten it to the specified torque. 8-33