Valve seat inspection/refacing

 

INSPECTION
Clean the intake and exhaust valves thoroughly to
[1]
remove carbon deposits.

Apply a light coat of Prussian Blue to the valve seats. Tap the valve against the valve seat several times using a hand-lapping tool [1], without rotating the valve to make a clear pattern.

 

Remove the valve and inspect the valve seat face width.

 

Inspect the valve seat face for:

 

• Damaged face:

– Replace the valve and reface the valve seat

• Uneven seat width:

– Bent or collapsed valve stem; Replace the valve and reface the valve seat

 

• Contact area (too low or too high area):

– Reface the valve seat

 

REFACING

 

Reface the valve seat using the following tools.

TOOLS:
Cutter holder, 4.5 mm	07781-0010600
Seat cutter, 27.5 mm (45° EX)	07780-0010200
Seat cutter, 33 mm (45° IN)	07780-0010800
Flat cutter, 27 mm (32° EX)	07780-0013300
Flat cutter, 30 mm (32° IN)	07780-0012200
Interior cutter, 30 mm (60° EX)	07780-0014000
Interior cutter, 37.5 mm (60° IN)	07780-0014100

 

VALVE SEAT WIDTH:

 

0.90 – 0.10 mm (0.035 – 0.043 in)

• Follow the refacer manufacturer’s operating instructions.

• Be careful not to grind the seat more than necessary.

1. Use a 45° seat cutter, remove any roughness or irregularities from the seat.

2. Use a 32° flat cutter, remove the top 1/4 of the existing valve seat material.

 

3. Use a 60° interior cutter, remove the bottom 1/4 of the existing valve seat material.

 

4. Using a 45° seat cutter, cut the seat to the proper width.

5. After cutting the seat, apply lapping compound to the valve face, and lap the valve using light pressure.

• Excessive lapping pressure may deform or damage
[1]
the seat.

• Change the angle of lapping tool [1] frequently to prevent uneven seat wear.

• Do not allow lapping compound to enter the guides.

 

After lapping, wash any residual compound off the cylinder head and valve and recheck the seat contact.

 

Old seat width

 

32°

 

 

Old seat width

 

60°

 

10-15

CYLINDER HEAD/VALVES

ASSEMBLY

 

INNER SPRING

 

STEM SEAL

 

SPRING SEAT

 

VALVE

 

GUIDE

 

 

			INTAKE VALVE
	Clean the cylinder head assembly with solvent and
	blow through all oil passages with compressed air.
	Install the spring seats [1] and new valve stem seals [2].
	Apply molybdenum oil solution to each valve stem
	sliding surface.
To avoid damage to	Insert the intake and exhaust valves [3] into the valve
the seal, turn the	guides.
valve slowly when
inserting.

 

 

Install the inner valve spring [1] and outer valve spring [2] with the tightly wound coils should facing the combustion chamber [3].

 

SHIM

 

COTTERS

 

 

RETAINER

 

 

OUTER SPRING

 

EXHAUST VALVE

[1] [2]

 

[3]

 

 

[2] [1]

 

 

[3]

 

10-16

CYLINDER HEAD/VALVES

 

Grease the cotters to ease installation.

To prevent loss of tension, do not compress the valve spring more than necessary.

 

 

Support the cylinder head above the work bench surface to prevent valve damage.

 

Do not allow dust and dirt to enter the crankcase.

 

Install the spring retainer [1].

 

Compress the valve spring using the special tools and install the valve cotters [2].

 

TOOLS:
[3] Valve spring compressor	07757-0010000
[4] Valve spring compressor
attachment	07959-KM30101

 

Tap the valve stems gently with two plastic hammer to firmly seat the cotters firmly.

 

Install the following:

 

– Spark plug (page 3-5)

– O2 sensor (page 4-47)

– Rocker arm (page 10-11)

 

 

INSTALLATION

 

Clean any gasket material from the cylinder mating surfaces.

 

Install the following:

 

– Dowel pins [1]

– New gasket [2]

– Cam chain guide A [3]

 

 

[4]

[1]/[2]

 

[3]

 

[3]		[2]

 

[1]

 

Be careful not to let the cylinder head bolts, washers and nuts fall into the crankcase.

 

Route the cam chain through the cylinder head and install the cylinder head [1] onto the cylinder.

 

Apply engine oil to the new cylinder head mounting nut [2] threads and seating surface.

 

Install and tighten the new cylinder head mounting nuts with new washers [3] in a crisscross pattern in two or three steps to the specified torque.

 

TORQUE:45 N·m (4.6 kgf·m, 33 lbf·ft)

 

Install and tighten the cylinder head bolts [4] securely. Install the following:

– Camshaft (page 10-9)

– Engine (page 15-7)

[2]/[3]

[4]			[1]

 

 

10-17

MEMO

CYLINDER/PISTON

 

 

SERVICE INFORMATION···························11-2 CYLINDER/PISTON ····································11-3

 

TROUBLESHOOTING·································11-2 CAM CHAIN TENSIONER ··························11-7

 

COMPONENT LOCATION··························11-2

 

11-1

CYLINDER/PISTON

SERVICE INFORMATION

 

GENERAL

 

• This section covers maintenance of the cylinder and piston. To service these parts, the engine must be removed from the frame.

 

• Take care not to damage the cylinder wall and piston.

• Be careful not to damage the mating surfaces when removing the cylinder. Do not tap the cylinder too hard during removal.

• Camshaft and rocker arm lubricating oil is fed through an oil passage in the cylinder. Clean the oil passage before installing cylinder.

• Clean all disassembled parts with cleaning solvent before inspection, use compressed air to dry the parts.

 

TROUBLESHOOTING