Disassembly and Reassembly
DISASSEMBLY
1. Using special tools (A), (B) & (C), compress valve springs and then remove valve cotters by using special tool (D).
Special Tool
(A): 09916-14510
(B): 09916-14910
(C): 09919-28610
(D): 09916-84511
2. Release special tool, and remove spring retainer and valve spring.
3. Remove valve from combustion chamber side.
4. Remove valve stem seal from valve guide, and then valve spring seat.
NOTE: Do not reuse seal once disassembled. Be sure to use new seal when assembling.
5. Using special tool (E) (Valve guide remover), drive valve guide out from combustion chamber side to valve spring side.
Special Tool
(E): 09916-44910
NOTE: Do not reuse valve guide once disassembled. Be sure to use new valve guide (Oversize) when assembling.
6. Place disassembled parts except valve stem seal and valve guide in order so that they can be installed in their original positions.
INSPECTION
Valve Guides
Using a micrometer and bore gauge, take diameter readings on valve stems and guides to check stem-to-guide clearance. Be sure to take reading at more than one place along the length of each stem and guide.
If clearance exceeds limit, replace valve and valve guide.
Valves
^ Remove all carbon from valves.
^ Inspect each valve for wear, burn or distortion at its face and stem and, as necessary, replace it.
^ Measure thickness of valve head. If measured thickness exceeds limit, replace valve.
^ Inspect valve stem end face for pitting and wear. If pitting or wear is found there, valve stem end may be resurfaced, but not too much to grind off its chamber. When it is worn out too much that its chamber is gone, replace valve.
^ Check each valve for radial runout with a dial gauge and "V" block. To check runout, rotate valve slowly. If runout exceeds its limit, replace valve.
Limit on valve head radial runout: 0.08 mm (0.003 inch)
^ Seating contact width:
Create contact pattern one each valve in the usual manner, i.e., by giving uniform coat of marking compound to valve seat and by rotatingly tapping seat with valve head. Valve lapper (tool used in valve lapping) must be used.
Pattern produced on seating face of valve must be a continuous ring without any break, and the width of pattern must be within specified range.
^ Valve seat repair:
A valve seat not producing a uniform contact with its valve or showing width of seating contact that is out of specified range must be repaired by regrinding or by cutting and regrinding and finished by lapping.
1. VALVE SEAT: Use valve seat cutters to make two cuts as illustrated in figure. Two cutters must be used: the first for making 15° angle, and the second for making 45° angle. The second cut must be made to produce desired seat width.
Seat width for valve seat: 1.1 - 1.3 mm (0.0433 - 0.0512 inch)
2. INTAKE VALVE SEAT: Use valve seat cutters to make three cuts as illustrated in figure. Three cutters must be used: the 1st for making 15° angle, the 2nd for making 60° angle, and 3rd for making 45° angle. The 3rd cut (45°) must be made to produce desired seat width.
Seat width for intake valve seat: 1.1 - 1.3 mm (0.0433 - 0.0512 inch)
3. VALVE LAPPING: Lap valve on seat in two steps, first with coarse size lapping compound applied to face and the second with fine-size compound, each time using valve lapper according to usual lapping method.
Cylinder Head
^ Remove all carbon from combustion chambers.
NOTE: Do not use any sharp-edged tool to scrape off carbon. Be careful not to scuff or nick metal surfaces when decarboning. The same applies to valves and valve seats, too.
^ Check cylinder head for cracks on intake and exhaust ports, combustion chambers, and head surface.
Using straightedge and thickness gauge, check flatness of gasketed surface at a total of 6 locations. If distortion limit, given below, is exceeded, correct gasketed surface with a surface plate and abrasive paper of about #400 (Waterproof silicon carbide abrasive paper): Place abrasive paper on and over surface plate, and rub gasketed surface against paper to grind off high spots. Should this fail to reduce thickness gauge readings to within limit, replace cylinder head.
Leakage of combustion gases from this gasketed joint is often due to warped gasketed surface: such leakage results in reduced power output.
Limit of distortion: 0.05 mm (0.002 inch)
^ Distortion of manifold seating faces:
Check seating faces of cylinder head for manifolds, using a straightedge and thickness gauge, in order to determine whether these faces should be corrected or cylinder head replaced.
Limit of distortion: 0.10 mm (0.004 inch)
Valve Springs
^ Referring to data given, check to be sure that each spring is in sound condition, free of any evidence of breakage or weakening. Remember, weakened valve springs can cause chatter, not to mention possibility of reducing power output due to gas leakage caused by decreased seating pressure.
^ Spring squareness:
Use a square and surface plate to check each spring for squareness in terms of clearance between end of valve spring and square. Valve springs found to exhibit larger clearance than limit given below must be replaced.
Valve spring squareness limit:
Inner spring 1.6 mm (0.063 inch)
Outer spring 1.8 mm (0.070 inch)
ASSEMBLY
1. Before installing valve guide into cylinder head, ream guide hole with special tool (11 mm reamer) so as to remove burrs and make it truly round.
Special Tool
(E): 09916-34542
(F): 09916-38210
2. Install valve guide to cylinder head.
Heat cylinder head uniformly at a temperature of 80 to 100°C (176 to 212°F) so that head will not be distorted, and drive new valve guide into hole with special tools. Drive in new valve guide until special tool (Valve guide installer) contacts cylinder head. After installing, make sure that valve guide protrudes by 13.5 mm (0.53 inch) from cylinder head.
Special Tool
(G): 09916-58210
(H): 09917-87810
NOTE:
^ Do not reuse valve guide once disassembled. Install new valve guide (Oversize).
^ Intake and exhaust valve guides are identical.
Valve guide oversize: 0.03 mm (0.0012 inch)
Valve guide protrusion (In and Ex): 13.5 mm (0.53 inch)
3. Ream valve guide bore with special tool (6.0 mm reamer). After reaming, clean bore.
Special Tool
(E): 09916-34542
(I): 09916-37810
4. Install valve spring seat to cylinder head.
5. Install new valve stem seal to valve guide. After applying engine oil to seal and spindle of special tool (Valve guide installer handle), fit oil seal to spindle, and then install seal to valve guide by pushing special tool by hand. After installing, check to be sure that seal is properly fixed to valve guide.
Special Tool
(J): 09917-98221
(K): 09916-58210
NOTE:
^ Do not reuse seal once disassembled. Be sure to install new seal.
^ When installing, never tap or hit special tool with a hammer or else. Install seal to guide only by pushing special tool by hand. Tapping or hitting special tool may cause damage to seal.
6. Install valve to valve guide. Before installing valve to valve guide, apply engine oil to stem seal, valve guide bore, and valve stem.
7. Install valve springs (inner and outer) and spring retainer. Each valve spring has top end (large-pitch end) and bottom end (small-pitch end). Be sure to position spring in place with its bottom end (small-pitch end) facing the bottom (valve spring seat side).
8. Using special tool (Valve lifter), compress valve spring and fit two valve cotters into groove in valve stem.
Special Tool
(A): 09916-14510
(B): 09916-14910
(C): 09916-84511
(D): 09919-28610