PERIODIC MAINTENANCE AND MINOR REPAIR6-106EAU03329Checking the spark plugsThe spark plugs are important enginecomponents, which are easy to check.Since heat and deposits will cause anyspark plug to slowly erode, the sparkplugs should be removed and checkedin accordance with the periodic mainte-nance and lubrication chart. In addition,the condition of the spark plugs can re-veal the condition of the engine.To remove a spark plug1. Remove the spark plug cap.2. Remove the spark plug as shown,with the spark plug wrench includ-ed in the owner’s tool kit.To check the spark plugs1. Check that the porcelain insulatoraround the center electrode oneach spark plug is a medium-to-light tan (the ideal color when themotorcycle is ridden normally).2. Check that all spark plugs installedin the engine have the same color.NOTE:_If any spark plug shows a distinctly dif-ferent color, the engine could be defec-tive. Do not attempt to diagnose suchproblems yourself. Instead, have aYamaha dealer check the motorcycle._3. Check each spark plug for elec-trode erosion and excessive car-bon or other deposits, and replaceit if necessary.1. Spark plug cap 1. Spark plug wrenchSpecified spark plug:CR9E (NGK) orU27ESR-N (DENSO)U5LV12.book Page 10 Thursday, June 27, 2002 5:49 PM
