Periodic maintenance and adjustment ECS00370 NOTICE EWS00710 WARNING Make sure that all cables, leads, etc., are routed properly before installing the shroud and covers. Be sure to use the specified spark plug and spark plug cap. Otherwise, the T.O.R.S. may not work properly. TIP When installing the shroud and covers, be sure to tighten all fasteners securely. Spark plugs are produced in several different thread lengths. The thread length or 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.
Al- so, if the reach is too short, carbon will form on the exposed threads resulting in combustion chamber hot spots and thread damage. Al- ways use a spark plug with the specified reach. ESU11782 Checking the spark plugs The spark plug is an important engine compo- nent and is easy to inspect. The condition of the spark plug 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 to a light tan color for a snowmobile that is being ridden normally. If a spark plug shows a dis- tinctly different color, there could be some- thing wrong with the engine.
For example, a very white center electrode porcelain color could indicate an intake track air leak or car- buretion problem for that cylinder. Do not at- tempt 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 plug because heat and deposits will cause a spark plug to slowly break down and erode. Consult a Yamaha dealer before changing to a different type of spark plug. Spark plug reach: 19.0 mm (0.75 in) 1. Spark plug gap 2. Spark plug reach Before installing any spark plug, measure the electrode gap with a wire thickness gauge and adjust to specification.
Specified spark plug: Manufacturer: NGK Model: CR9EB Spark plug gap: 0.7–0.8 mm (0.028–0.031 in) 43