Maintenance

EMU28956

Cleaning and adjusting spark plug

The spark plug is an important engine component and is easy to inspect. The condition of the spark plug can indicate something about the condition of the engine. For example, if the center electrode porcelain is very white, this could indicate an intake air leak or carburetion problem in that cylinder. Do not attempt to diagnose any problems yourself. Instead, take the outboard motor to a Yamaha dealer. You should periodically remove and inspect the spark plug because heat and deposits will cause the spark plug to slowly break down and erode.

1.Remove the spark plug caps from the spark plugs.

2.Remove the spark plug. If electrode ero- sion becomes excessive, or if carbon and other deposits are excessive, you should replace the spark plug with another of the correct type. WARNING! When remov- ing or installing a spark plug, be care- ful not to damage the insulator. A damaged insulator could allow exter- nal sparks, which could lead to explo- sion or fire. [EWM00561]

Standard spark plug:

B7HS-10

3.Be sure to use the specified spark plug, otherwise the engine may not operate properly. Before fitting the spark plug, measure the electrode gap with a wire thickness gauge; replace it if out of spec- ification.

1.Spark plug gap

2.Spark plug part number

3.Spark plug I.D. mark (NGK)

Spark plug gap:

0.9–1.0 mm (0.035–0.039 in)

4.When fitting the plug, wipe off any dirt from the threads, and then screw it in to the correct torque.

Spark plug torque:

25.0 Nm (2.55 kgf-m, 18.4 ft-lb)

TIP:

If a torque-wrench is not available when you are fitting a spark plug, a good estimate of the correct torque is 1/4 to 1/2 a turn past finger- tight. Have the spark plug adjusted to the correct torque as soon as possible with a torque- wrench.

EMU37450

Checking fuel filter

Check the fuel filter periodically. If any water or foreign matter is found in the filter, clean or replace it. For cleaning or replacement of the fuel filter, consult your Yamaha dealer.

EMU29043

Inspecting idling speed

EWM00451

WARNING

●Do not touch or remove electrical parts when starting or during operation.

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