Yamaha 2C Owner's Manual

Maintenance37EMU28956Cleaning and adjusting spark plugThe spark plug is an important engine compo-nent and is easy to inspect. The condition ofthe spark plug can indicate something aboutthe condition of the engine. For example, if thecenter electrode porcelain is very white, thiscould indicate an intake air leak or carburetionproblem in that cylinder. Do not attempt to di-agnose any problems yourself. Instead, takethe outboard motor to a Yamaha dealer. Youshould periodically remove and inspect thespark plug because heat and deposits willcause the spark plug to slowly break downand erode.1. Remove the spark plug caps from thespark plugs.2. Remove the spark plug. If electrode ero-sion becomes excessive, or if carbon andother deposits are excessive, you shouldreplace the spark plug with another of thecorrect type. WARNING! When remov-ing or installing a spark plug, be care-ful not to damage the insulator. Adamaged insulator could allow exter-nal sparks, which could lead to explo-sion or fire. [EWM00561]3. Be sure to use the specified spark plug,otherwise the engine may not operateproperly. Before fitting the spark plug,measure the electrode gap with a wirethickness gauge; replace it if out of spec-ification.4. When fitting the plug, wipe off any dirtfrom the threads, and then screw it in tothe correct torque.TIP:If a torque-wrench is not available when youare fitting a spark plug, a good estimate of thecorrect torque is 1/4 to 1/2 a turn past finger-tight. Have the spark plug adjusted to the cor-rect torque as soon as possible with a torque-wrench.EMU30811Inspecting idling speedWARNINGEWM01440 Do not touch or remove electrical partswhen starting or during operation. Keep hands, hair, and clothes away fromthe flywheel and other rotating partswhile the engine is running. The propeller rotates whenever the en-gine is running. Do not move the throttlecontrol lever from the start position dur-Standard spark plug:BR7HS1. Spark plug gap2. Spark plug part number3. Spark plug I.D. mark (NGK)Spark plug gap:0.6–0.7 mm (0.024–0.028 in)Spark plug torque:25.0 Nm (2.55 kgf-m, 18.4 ft-lb)