Yamaha XMax YP400RA - Owner's Manual > Checking the spark plug

The spark plug is an important engine component, which is easy to check.

Since heat and deposits will cause any spark plug to slowly erode, the spark plug should be removed and checked in accordance with the periodic maintenance and lubrication chart. In addition, the condition of the spark plug can reveal the condition of the engine.

To remove the spark plug

  1. Place the vehicle on the centerstand
  2. Open the seat.
  3. Remove the rear storage compartment by removing the bolts.

To remove the spark plug

  1. Storage compartment
  2. Bolt

4. Remove the spark plug cap.

To remove the spark plug

  1. Spark plug cap

5. Remove the spark plug as shown, with the spark plug wrench included in the owner's tool kit.

To remove the spark plug

  1. Spark plug wrench

To check the spark plug

1. Check that the porcelain insulator around the center electrode of the spark plug is a medium-to-light tan (the ideal color when the vehicle is ridden normally).


If the spark plug shows a distinctly different color, the engine could be operating improperly. Do not attempt to diagnose such problems yourself. Instead, have a Yamaha dealer check the vehicle.

2. Check the spark plug for electrode erosion and excessive carbon or other deposits, and replace it if necessary.

Specified spark plug:


3. Measure the spark plug gap with a wire thickness gauge and, if necessary, adjust the gap to specification.

To check the spark plug

  1. Spark plug gap

Spark plug gap:

0.7-0.8 mm (0.028-0.031 in)

To install the spark plug

1. Clean the surface of the spark plug gasket and its mating surface, and then wipe off any grime from the spark plug threads.

2. Install the spark plug with the spark plug wrench, and then tighten it to the specified torque.

Tightening torque:

Spark plug: 12.5 Nm (1.25 m*kgf, 9.04 ft*lbf)


If a torque wrench is not available when installing a spark plug, a good estimate of the correct torque is 1/4- 1/2 turn past finger tight. However, the spark plug should be tightened to the specified torque as soon as possible.

3. Install the spark plug cap.


Make sure the spark plug wire is fastened in the clamp as shown.

To install the spark plug

  1. Spark plug cap
  2. Spark plug lead clamp
  3. Spark plug lead

4. Place the rear storage compartment in the original position and install the bolts.

5. Close the seat.

See also:

 Yamaha XMax YP400RA - Owner's Manual > Removing and installing panels

The panels shown need to be removed to perform some of the maintenance jobs described in this chapter. Refer to this section each time a panel needs to be removed and installed. Panel A Panel B Panel C Panel D

 Yamaha XMax YP400RA - Owner's Manual > Engine oil and oil filter element

The engine oil level should be checked before each ride. In addition, the oil must be changed and the oil filter element replaced at the intervals specified in the periodic maintenance and lubrication chart and when the oil change indicator comes on.

Maxi Scooters: