2012 Yamaha Motorsports Apex SE Owners Manual - Page 59
2012 Yamaha Motorsports Apex SE Manual
Page 59 highlights
Periodic maintenance and adjustment G When installing the shroud and covers, be sure to tighten the fasteners securely. ESU11784 Checking the spark plugs The spark plugs are important engine components and are easy to inspect. The condition of the spark plugs can indicate 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-tolight tan color for a snowmobile that is being ridden normally. If any 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 snowmobile to a Yamaha dealer for inspection and possible repairs. You should periodically remove and inspect the spark plugs because heat and deposits will cause any spark plug to slowly break down and erode. Consult a Yamaha dealer before changing to a different type of spark plug. Specified spark plug: Manufacturer: NGK Model: CR9EB EWS00710 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 the reach is too short, carbon will form on the exposed threads resulting in combustion chamber hot spots and thread damage. Always use a spark plug with the specified reach. Spark plug reach: 19.0 mm (0.75 in) 1. Spark plug gap 2. Spark plug reach Before installing any spark plug, measure the spark plug gap with a wire thickness gauge and adjust to specification. Spark plug gap: 0.7-0.8 mm (0.028-0.031 in) When installing the spark plug, always clean the gasket surface. Wipe off any grime from the threads and tighten the spark plug to the specified torque. Spark plug tightening torque: 13 Nm (1.3 m·kgf, 9.4 ft·lbf) WARNING Be sure to use the specified spark plug and spark plug cap. Otherwise, the T.O.R.S. may not work properly. Spark plugs are produced in several different thread lengths. The thread length or reach is the distance from the spark plug gasket seat 53