Yamaha XMAX YP125R - Service manual > Camshaft (YP125R)

Removing the rocker arms and camshaft

Removing the camshaft

1. Remove:

• Camshaft "1"

TIP

Screw an M8 bolt "2" into the threaded end of the camshaft, and then pull out the camshaft.

Checking the camshaft

1. Check:

• Camshaft lobes

Blue discoloration/pitting/scratches → Replace the camshaft.

2. Measure:

• Camshaft lobe dimensions "a" and "b" Out of specification → Replace the camshaft.

Camshaft lobe dimensions Intake A 30.225-30.325 mm (1.1900- 1.1939 in)

Limit 30.125 mm (1.1860 in)

Intake B 25.064-25.164 mm (0.9868- 0.9907 in)

Limit 24.964 mm (0.9828 in)

Exhaust A 30.261-30.361 mm (1.1914- 1.1953 in)

Limit 30.161 mm (1.1874 in)

Exhaust B 25.121-25.221 mm (0.9890- 0.9930 in)

Limit 25.021 mm (0.9851 in)

3. Check:

• Camshaft oil passage

Obstruction → Blow out with compressed air.

Checking the decompression system

1. Check:

• Decompression system

a. Check the decompression system with the camshaft sprocket and the decompression cam installed to the camshaft.

b. Check that the decompression lever "1" moves smoothly.

c. Without operating the decompression lever, check that the decompression cam "2" projects from the camshaft (exhaust cam) as shown in the illustration "A".

d. Move the decompression lever in the direction of the arrow shown and check that the decompression cam does not project from the camshaft (exhaust cam) as shown in the illustration "B".

Checking the rocker arms and rocker arm shafts

The following procedure applies to all of the rocker arms and rocker arm shafts.

1. Check:

• Rocker arm
• Rocker arm roller "1"

Damage/wear → Replace.

2. Check:

• Rocker arm shaft

Blue discoloration/excessive wear/pitting/ scratches → Replace or check the lubrication system.

3. Measure:

• Rocker arm inside diameter "a"

Out of specification → Replace.

Rocker arm inside diameter 9.985-10.000 mm (0.3931- 0.3937 in)

Limit 10.015 mm (0.3943 in)

4. Measure:

• Rocker arm shaft outside diameter "a" Out of specification → Replace.

Rocker arm shaft outside diameter 9.966-9.976 mm (0.3924-0.3928 in)

Limit 9.940 mm (0.3913 in)

5. Calculate:

• Rocker-arm-to-rocker-arm-shaft clearance

TIP

Calculate the clearance by subtracting the rocker arm shaft outside diameter from the rocker arm inside diameter.

Out of specification → Replace the defective part(s).

Rocker-arm-to-rocker-arm-shaft clearance 0.009-0.034 mm (0.0004-0.0013 in)

Limit 0.075 mm (0.0030 in)

Installing the camshaft and rocker arms

1. Lubricate:

• Camshaft

Recommended lubricant

Camshaft

Molybdenum disulfide grease

Camshaft bearing

Engine oil

2. Lubricate:

• Rocker arms
• Rocker arm shafts

Recommended lubricant

Molybdenum disulfide oil

3. Install:

• Rocker arms
• Rocker arm shafts "1"

TIP

• Make sure that the cutout "a" in each rocker arm shaft is facing downward as shown in the illustration.
• Make sure the rocker arm shafts (intake and exhaust) are completely pushed into the cylinder head.

4. Install:

• Camshaft "1"

TIP

Make sure that the camshaft projections "a" and hole "b" are positioned as shown in the illustration.

5. Install:

• Camshaft retainer

Camshaft retainer bolt 7 Nm (0.7 m*kgf, 5.1 ft*lbf) LOCTITE

See also: