CYLINDER HEAD/VALVES
8-3
SERVICE INFORMATION
GENERAL
• This section covers service of the rocker arm, camshaft, cylinder head and valve.
• The cylinder head services can be done with the engine installed in the frame.
• Be careful not to damage the mating surfaces when removing the cylinder head cover and cylinder head. Do not strike
the cylinder head cover and cylinder head too hard during removal.
• When disassembling, mark and store the disassembled parts to ensure that they are reinstalled in their original loca-
tions.
• Clean all disassembled parts with cleaning solvent and dry them by blowing them off with compressed air before
inspection.
• Camshaft and rocker arm lubricating oil is fed through oil passages in the cylinder head and camshaft holder. Clean the
oil passages before assembling the cylinder head and cover.
SPECIFICATIONS
Unit: mm (in)
TORQUE VALUES
ITEM STANDARD SERVICE LIMIT
Cylinder compression at 400 min
-1
(rpm) 1,373 ± 98 kPa
(14.0 ± 1.0 k g f/cm
2
, 199 ± 14 psi)
–
Valve clearance IN 0.15 ± 0.02 (0.006 ± 0.001) –
EX 0.20 ± 0.02 (0.008 ± 0.001) –
Camshaft Cam lobe height IN 40.609 – 40.769 (1.5988 – 1.6051) 40.58 (1.598)
EX 40.695 – 40.855 (1.6022 – 1.6085) 40.67 (1.601)
Runout – 0.05 (0.002)
Journal O.D. 21.959 – 21.980 (0.8645 – 0.8654) 21.90 (0.862)
Oil clearance 0.020 – 0.062 (0.0008 – 0.0024) 0.10 (0.004)
Rocker arm,
rocker arm
shaft
Rocker arm shaft O.D. IN/EX 11.983 – 11.994 (0.4718 – 0.4722) 11.92 (0.469)
Rocker arm I.D. IN/EX 12.006 – 12.024 (0.4727 – 0.4734) 12.05 (0.474)
Rocker arm-to-shaft clearance 0.012 – 0.041 (0.0005 – 0.0016) 0.14 (0.006)
Valve,
valve guide
Valve stem O.D. IN 5.475 – 5.490 (0.2156 – 0.2161) 5.460 (0.2150)
EX 5.460 – 5.475 (0.2150 – 0.2156) 5.455 (0.2148)
Valve guide I.D. IN/EX 5.500 – 5.512 (0.2165 – 0.2170) 5.54 (0.218)
Stem-to-guide clear-
ance
IN 0.010 – 0.037 (0.0004 – 0.0015) 0.07 (0.003)
EX 0.025 – 0.052 (0.0010 – 0.0020) 0.09 (0.004)
Valve guide projection
above cylinder head
IN 12.5 – 12.7 (0.49 – 0.50) –
EX 16.7 – 16.9 (0.66 – 0.67) –
Valve seat width IN/EX 0.90 – 1.10 (0.035 – 0.043) 1.5 (0.06)
Valve spring Free length IN/EX 44.91 (1.768) 43.9 (1.73)
Cylinder head warpage – 0.10 (0.004)
Valve adjusting screw lock nut 23 N·m (2.3 kgf·m, 17 lbf·ft) Apply engine oil to the threads and seating
surface.
Cylinder head cover bolt 10 N·m (1.0 kgf·m, 7 lbf·ft)
Cylinder head bolt 23 N·m (2.3 kgf·m, 17 lbf·ft) Apply engine oil to the threads and seating
surface.
Cylinder head nut 40 N·m (4.1 kgf·m, 30 lbf·ft) Apply engine oil to the threads and seating
surface.
Cam sprocket bolt 23 N·m (2.3 kgf·m, 17 lbf·ft) Apply locking agent.
Cam chain tensioner bolt 10 N·m (1.0 kgf·m, 7 lbf·ft)
Camshaft holder bolt 23 N·m (2.3 kgf·m, 17 lbf·ft) Apply engine oil to the threads and seating
surface.
Cylinder head sealing bolt 44 N·m (4.5 kgf·m, 32 lbf·ft) ALOC bolt; replace with a new one.
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