2007 Yamaha Motorsports Grizzly 660 Auto. 4x4 Owners Manual - Page 109
2007 Yamaha Motorsports Grizzly 660 Auto. 4x4 Manual
Page 109 highlights
EBU23221 Checking the spark plug The spark plug is an important engine component, which is easy to check. Since heat and deposits will cause any spark plug to slowly erode, the spark plug should be removed and checked in accordance with the periodic maintenance and lubrication chart. In addition, the condition of the spark plug can reveal the condition of the engine. To remove the spark plug 1. Remove panel A. (See page 8-9.) 2. Remove the spark plug cap. 3. Remove the spark plug as shown, with the spark plug wrench included in the owner's tool kit. 1. Spark plug wrench To check the spark plug 1. Check that the porcelain insulator around the center electrode of the spark plug is a medium-to-light tan (the ideal color when the ATV is ridden normally). NOTE: If the spark plug shows a distinctly different color, the engine could be operating improperly. Do not attempt to diagnose such problems yourself. Instead, have a Yamaha dealer check the ATV. 8-16 8 1. Spark plug cap