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General
This section covers service of the cylinder head, valves, camshafts and rocker arms. To service these parts, the engine must be removed from the frame.
When disassembling, mark and store the disassembled parts to ensure that they are reinstalled in their original locations. Clean all disassemble parts with cleaning solvent and dry them with compressed air before inspection.
Camshaft and rocker arm lubricating oil is fed through oil passages in the cylinder head and head cover. Clean the oil passages before assembling the cylinder head and head cover.
Pour clean engine oil into the oil pockets in the cylinder head during assembly to lubricate the camshaft.
Be careful not to damage the mating surfaces when removing the head cover and cylinder head.
Specification
ITEM | STANDARD | SERVICE LIMIT Unit: mm (in) | ||
Cylinder compression | 657 kPa (6.7 kgf/cm2, 95 psi) at 320 rpm | — | ||
Valve clearance | IN | 0.13±0.02 (0.005±0.001) | — | |
EX | 0.32±0.02 (0.013±0.001) | — | ||
Camshaft | Cam lobe height | IN | 39.953 - 40.033 (1.5729 - 1.5761) | 39.92 (1.572) |
EX | 39.423 - 39.503 (1.5521 - 1.5552) | 39.40 (1.551) | ||
Runout | — | 0.05 (0.002) | ||
Oil clearance | 0.040 - 0.101 (0.0016 - 0.0040) | 0.12 (0.005) | ||
Rocker arm, rocker arm shaft | Rocker arm shaft O.D. | IN/EX | 13.976 - 13.994 (0.5502 - 0.5509) | 13.92 (0.548) |
Rocker arm I.D. | IN/EX | 14.006 - 14.024 (0.5514 - 0.5521) | 14.05 (0.553) | |
Rocker arm-to-rocker arm shaft clearance | 0.012 - 0.048 (0.0005 - 0.0019) | 0.14 (0.006) | ||
Valve, valve guide | Valve stem O.D. | IN | 6.575 - 6.590 (0.2589 - 0.2594) | 6.57 (0.259) |
EX | 7.955 - 7.970 (0.3132 - 0.3138) | 7.94 (0.313) | ||
Valve guide I.D. | IN | 6.600 - 6.615 (0.2598 - 0.2604) | 6.635 (0.2612) | |
EX | 8.000 - 8.015 (0.3150 - 0.3156) | 8.055 (0.3171) | ||
Stem-to-guide clearance | IN | 0.010 - 0.040 (0.0039 - 0.0016) | 0.08 (0.003) | |
EX | 0.030 - 0.060 (0.0012 - 0.0024) | 0.12 (0.005) | ||
Valve guide projection above cylinder head | IN | 16.4 - 16.6 (0.646 - 0.654) | — | |
EX | 17.7- 17.9 (0.697-0.705) | — | ||
Valve seat width | IN | 1.10- 1.30 (0.043-0.051) | 1.70 (0.669) | |
EX | 1.40- 1.60 (0.055-0.063) | 2.00 (0.079) | ||
Valve spring free length | IN | 43.5 (1.71) | 41.9 (1.65 ) | |
EX | 44.2 (1.74) | 42.4 (1.67) | ||
Cylinder head warpage | — | 0.10 (0.004) |
Torque values
Spark plug | 18 N·m (1.8 kgf·m, 13 lbf·ft) | |
Spark plug sleeve | 18 N·m (1.8 kgf·m, 13 lbf·ft) | Apply oil to the threads and flange surface. |
Reed valve cover bolt | 5.1 N·m (0.52 kgf·m, 3.8 lbf·ft) | |
Cylinder head cover bolt (8 mm) | 26 N·m (2.7 kgf·m, 20 lbf·ft) | |
- (6 mm) | 12 N·m (1.2 kgf·m, 9 lbf·ft) | |
Cylinder head nut (10 mm) | 49 N·m (5.0 kgf·m, 39 lbf·ft) | Apply oil to the threads and flange surface. |
- (8 mm) | 26 N·m (2.7 kgf·m, 20 lbf·ft) | Apply oil to the threads and flange surface. |
Camshaft holder bolt | 26 N·m (2.7 kgf·m, 20 lbf·ft) | Apply oil to the threads and flange surface. |
Cam sprocket bolt | 23 N·m (2.3 kgf·m, 17 lbf·ft) | |
Valve adjusting screw lock nut | 22 N·m (2.2 kgf·m, 16 lbf·ft) | |
Cam chain tensioner bolt | 12 N·m (1.2 kgf·m, 9 lbf·ft) |
Tools
Valve guide driver, 6.6 mm | 07942-6570100 | |
Valve spring compressor | 07757-0010000 | |
Valve seat cutters | Equivalent commercially available in U.S.A. | |
Seat cutter, 40 mm (45° IN) | 07780-0010500 | |
Seat cutter, 46 mm (45° EX) | 07780-0011200 | |
Flat cutter, 38.5 mm (32° IN) | 07780-0012400 | |
Flat cutter, 50 mm (32° EX) | 07780-0013600 | |
Interior cutter, 34 mm (60° IN) | 07780-0014700 | |
Interior cutter, 45 mm (60° EX) | 07780-0014800 | |
Cutter holder, 6.6 mm | 07781-0010202 or 07942-ZE2000D (U.S.A, only) | |
Holder attachment | 07930-KA50100 | |
Valve guide reamer, 6.6 mm | 07984-657010D | |
Valve guide driver, 8 mm | 07ZMD-MCHA100 | |
Cutter holder, 8 mm | 07ZMH-MCH0100 | Equivalent commercially available in U.S.A. |
Valve guide reamer, 8 mm | 07ZMH-MCHA200 |