Yamaha XMAX YP125R - Service manual > Checking the spark plug

1. Disconnect:

• Spark plug cap "1"

2. Remove:

• Spark plug

NOTICE

Before removing the spark plug, blow away any dirt accumulated in the spark plug well with compressed air to prevent it from falling into the cylinder.

3. Check:

• Spark plug type

Incorrect → Change.

Manufacturer/model NGK/DPR8EA-9

4. Check:

• Electrode "1"

Damage/wear → Replace the spark plug.

• Insulator "2"

Abnormal color → Replace the spark plug.

Normal color is medium-to-light tan.

5. Clean:

• Spark plug (with a spark plug cleaner or wire brush)

6. Measure:

• Spark plug gap "a" (with a wire thickness gauge) Out of specification → Regap.

Spark plug gap 0.8-0.9 mm (0.031-0.035 in)

7. Install:

• Spark plug

Spark plug 18 Nm (1.8 m*kgf, 13 ft*lbf)

TIP

Before installing the spark plug, clean the spark plug and gasket surface.

8. Connect:

• Spark plug cap

Checking the ignition timing

TIP

Prior to checking the ignition timing, check the wiring connections of the entire ignition system.

Make sure that all connections are tight and free of corrosion.

1. Stand the vehicle on a level surface.

TIP

Place the vehicle on the centerstand.

2. Remove:

• Timing mark accessing plug "1"

3. Connect:

• Timing light "1" (onto the spark plug lead)

Timing light 90890-03141

Inductive clamp timing light YU-03141

4. Check:

• Ignition timing

a. Start the engine, warm it up for several minutes, and then let it run at the specified engine idling speed.

Engine idling speed 1450-1650 r/min

b. Check that the stationary pointer "a" on the generator cover is within the firing range "b" on the generator rotor.

Incorrect firing range → Check the ignition system.

TIP

The ignition timing is not adjustable.

5. Disconnect:

• Timing light

6. Install:

• Timing mark accessing plug (along with the O-ring )

Timing mark accessing plug 8 Nm (0.8 m*kgf, 5.8 ft*lbf)

Measuring the compression pressure

TIP

Insufficient compression pressure will result in a loss of performance.

1. Remove:

• Storage box

2. Measure:

• Valve clearance

Out of specification → Adjust.

3. Start the engine, warm it up for several minutes, and then turn it off.

4. Disconnect:

• Spark plug cap

5. Remove:

• Spark plug

NOTICE

Before removing the spark plug, use compressed air to blow away any dirt accumulated in the spark plug well to prevent it from falling into the cylinder.

6. Install:

• Compression gauge "1"

Compression gauge 90890-03081

Engine compression tester YU-33223

7. Measure:

• Compression pressure

Out of specification → Refer to steps (c) and (d).

Standard compression pressure (at sea level) 1400 kPa/500 r/min (14.0 kgf/cm²/500 r/min, 199.1 psi/500 r/min)

Minimum-maximum 1120-1570 kPa (11.2-15.7 kgf/cm², 159.3-223.3 psi)

a. Set the main switch to "ON".

b. With the throttle wide open, crank the engine until the reading on the compression gauge stabilizes.

WARNING

To prevent sparking, ground the spark plug lead before cranking the engine.

c. If the compression pressure is above the maximum specification, check the cylinder head, valve surfaces and piston crown for carbon deposits.

Carbon deposits → Eliminate.

d. If the compression pressure is below the minimum specification, pour a teaspoonful of engine oil into the spark plug bore and measure again.

Refer to the following table.

8. Install:

• Spark plug

Spark plug 18 Nm (1.8 m*kgf, 13 ft*lbf)

9. Connect:

• Spark plug cap

10.Install:

• Storage box

Checking the engine oil level

1. Stand the vehicle on a level surface.

TIP

• Place the vehicle on the centerstand
• Make sure the vehicle is upright.

2. Start the engine, warm it up for several minutes, and then turn it off.

3. Remove:

• Dipstick "1"

4. Check:

• Engine oil level

The engine oil level should be between the minimum level mark "a" and maximum level mark "b".

Below the minimum level mark → Add the recommended engine oil to the proper level.

TIP

• Before checking the engine oil level, wait a few minutes until the oil has settled.
• Do not screw the dipstick in when inspecting the oil level.

Type

SAE 10W-30, SAE 10W-40, SAE 15W-40, SAE 20W-40 or SAE 20W-50

Recommended engine oil grade API service SF, SG type or higher, JASO standard MA

NOTICE

Do not allow foreign materials to enter the crankcase.

5. Start the engine, warm it up for several minutes, and then turn it off.

6. Check the engine oil level again.

TIP

Before checking the engine oil level, wait a few minutes until the oil has settled.

7. Install:

• Dipstick

See also: