Yamaha Tracer MT09TRA - Service manual > Valves and valve springs

Removing the valves

The following procedure applies to all of the valves and related components.

TIP

Before removing the internal parts of the cylinder head (e.g., valves, valve springs, valve seats), make sure the valves properly seal.

1. Remove:

• Valve lifter "1"
• Valve pad "2"

TIP

Make a note of the position of each valve lifter and valve pad so that they can be reinstalled in their original place.

2. Check:

• Valve sealing

Leakage at the valve seat → Check the valve face, valve seat, and valve seat width.

Refer to "CHECKING THE VALVE SEATS"

a. Pour a clean solvent "a" into the intake and exhaust ports.

b. Check that the valves properly seal.

TIP

There should be no leakage at the valve seat "1".

3. Remove:

• Valve cotters

TIP

Remove the valve cotters by compressing the valve spring with the valve spring compressor "1" and the valve spring compressor attachment "2".

Valve spring compressor 90890-04019

Valve spring compressor YM-04019

Valve spring compressor attachment 90890-04108

Valve spring compressor adapter 22 mm YM-04108

4. Remove:

• Valve spring retainer "1"
• Valve spring "2"
• Valve "3"
• Valve stem seal "4"
• Valve spring seat "5"

TIP

Identify the position of each part very carefully so that it can be reinstalled in its original place.

Checking the valves and valve guides

The following procedure applies to all of the valves and valve guides.

1. Measure:

• Valve-stem-to-valve-guide clearance Out of specification → Replace the valve guide.

Valve-stem-to-valve-guide clearance = Valve guide inside diameter "a" - Valve stem diameter "b"

Valve-stem-to-valve-guide clearance (intake) 0.010-0.037 mm (0.0004-0.0015 in)

Limit 0.080 mm (0.0032 in) Valve-stem-to-valve-guide clearance (exhaust) 0.025-0.052 mm (0.0010-0.0020 in)

Limit 0.100 mm (0.0039 in)

2. Replace:

• Valve guide

TIP

To ease valve guide removal and installation, and to maintain the correct fit, heat the cylinder head to 100 ºC (212 ºF) in an oven.

a. Remove the valve guide with the valve guide remover "1".

b. Install the new valve guide with the valve guide installer "2" and valve guide remover "1".

Valve guide position 13.3-13.7 mm (0.52-0.54 in)

a. Valve guide position

c. After installing the valve guide, bore the valve guide with the valve guide reamer "3" to obtain the proper valve-stem-to-valve-guide clearance.

TIP

After replacing the valve guide, reface the valve seat.

Valve guide remover (ø4.5) 90890-04116

Valve guide remover (4.5 mm) YM-04116

Valve guide installer (ø4.5) 90890-04117

Valve guide installer (4.5 mm) YM-04117

Valve guide reamer (ø4.5) 90890-04118

Valve guide reamer (4.5 mm) YM-04118

3. Eliminate:

• Carbon deposits (from the valve face and valve seat)

4. Check:

• Valve face.

  Pitting/wear → Grind the valve face.

• Valve stem end.

  Mushroom shape or diameter larger than the body of the valve stem → Replace the valve.

5. Measure:

• Valve stem runout.

  Out of specification → Replace the valve.

TIP

• When installing a new valve, always replace the valve guide.
• If the valve is removed or replaced, always replace the valve stem seal.

Valve stem runout 0.010 mm (0.0004 in)

Checking the valve seats

The following procedure applies to all of the valves and valve seats.

1. Eliminate:

• Carbon deposits (from the valve face and valve seat)

2. Check:

• Valve seat Pitting/wear → Replace the cylinder head.

3. Measure:

• Valve seat contact width "a" Out of specification → Replace the cylinder head.

Valve seat contact width (intake) 0.90-1.10 mm (0.0354-0.0433 in)

Limit 1.6 mm (0.06 in)

Valve seat contact width (exhaust) 1.10-1.30 mm (0.0433-0.0512 in)

Limit 1.8 mm (0.07 in)

a. Apply blue layout fluid "b" onto the valve face.

b. Install the valve into the cylinder head.

c. Press the valve through the valve guide and onto the valve seat to make a clear impression.

d. Measure the valve seat contact width.

TIP

Where the valve seat and valve face contacted one another, the blue layout fluid will have been removed.

4. Lap:

• Valve face
• Valve seat

TIP

After replacing the cylinder head or replacing the valve and valve guide, the valve seat and valve face should be lapped.

a. Apply a coarse lapping compound "a" to the valve face

NOTICE

Do not let the lapping compound enter the gap between the valve stem and the valve guide.

b. Apply molybdenum disulfide oil onto the valve stem.

c. Install the valve into the cylinder head.

d. Turn the valve until the valve face and valve seat are evenly polished, then clean off all of the lapping compound.

TIP

For the best lapping results, lightly tap the valve seat while rotating the valve back and forth between your hands.

e. Apply a fine lapping compound to the valve face and repeat the above steps.

f. After every lapping procedure, be sure to clean off all of the lapping compound from the valve face and valve seat.

g. Apply blue layout fluid "b" onto the valve face

h. Install the valve into the cylinder head.

i. Press the valve through the valve guide and onto the valve seat to make a clear impression.

j. Measure the valve seat contact width "c" again. If the valve seat width is out of specification, reface and lap the valve seat.

Checking the valve springs

The following procedure applies to all of the valve springs.

1. Measure:

• Valve spring free length "a".

  Out of specification → Replace the valve spring.

Free length (intake) 39.31 mm (1.55 in)

Limit 37.34 mm (1.47 in) Free length (exhaust) 37.78 mm (1.49 in)

Limit 35.89 mm (1.41 in)

2. Measure:

• Compressed valve spring force "a" Out of specification → Replace the valve spring.

b. Installed length

Installed compression spring force (intake) 192.00-220.00 N (19.58-22.43 kgf, 43.16-49.46 lbf)

Installed compression spring force (exhaust) 162.00-186.00 N (16.52-18.97 kgf, 36.42-41.81 lbf)

Installed length (intake) 32.90 mm (1.30 in)

Installed length (exhaust) 32.00 mm (1.26 in)

3. Measure:

• Valve spring tilt "a".

  Out of specification → Replace the valve spring.

Spring tilt (intake) 1.7 mm (0.07 in)

Spring tilt (exhaust) 1.6 mm (0.06 in)

Checking the valve lifters

The following procedure applies to all of the valve lifters.

1. Check:

• Valve lifter

Damage/scratches →  Replace the valve lifters and cylinder head.

Installing the valves

The following procedure applies to all of the valves and related components.

1. Deburr:

• Valve stem end (with an oil stone)

2. Lubricate:

• Valve stem "1"
• Valve stem seal "2" (with the recommended lubricant)

Recommended lubricant Molybdenum disulfide oil

3. Install:

• Valve spring seat "1"
• Valve stem seal "2"
• Valve "3"
• Valve spring "4"
• Valve spring retainer "5" (into the cylinder head)

TIP

• Make sure each valve is installed in its original place.
• Install the valve springs with the larger pitch "a" facing up.

b. Smaller pitch

4. Install:

• Valve cotters "1"

TIP

Install the valve cotters by compressing the valve spring with the valve spring compressor "2" and the valve spring compressor attachment "3".

Valve spring compressor 90890-04019

Valve spring compressor YM-04019

Valve spring compressor attachment 90890-04108

Valve spring compressor adapter 22 mm YM-04108

5. To secure the valve cotters onto the valve stem, lightly tap the valve tip with a soft-face hammer.

NOTICE

Hitting the valve tip with excessive force could damage the valve.

6. Lubricate:

• Valve pad (with the recommended lubricant)

Recommended lubricant Molybdenum disulfide oil

• Valve lifter (with the recommended lubricant)

Recommended lubricant Engine oil

7. Install:

• Valve pad
• Valve lifter

TIP

• The valve lifter must move smoothly when rotated with a finger.
• Each valve lifter and valve pad must be reinstalled in its original position.

See also: