Page 9-0


really big verson

Page 9-1

SERVICE INFORMATION

GENERAL

SPECIFICATIONS

Unit: mm (in)
ITEMSTANDARDService limit
Compression pressure1,324 ± 196 kPa
(13.5 ± 2.0kg/cm², 192 ± 28 psi)
---
CamshaftCam lobe heightIN38.189 (1.5035)38.17 (1.503)
EX38.213 (1.5044)38.19 (1.504)
Journal O.D.21.959-21.980 (0.8645-0.8654)21.95 (0.864)
Runout0.030 (0.0012)0.05 (0.002)
Oil Clearance0.040-0.093 (0.0015-0.0037)0.11 (0.004)
Rocker armRocker arm I.D.IN/EX12.000-12.018 (0.4724-0.4731)12.03 (0.474)
Rocker arm shaft O.D.IN/EX11.966-11.984 (0.4711-0.4718)11.96 (0.471)
Valve and
valve guide
Valve stem O.D.IN5.475-5.490 (0.2156-0.2161)5.47 (0.215)
EX6.555-6.570 (0.2580-0.2587)6.55 (0.258)
Valve guide I.D.IN5.500-5.512 (0.2165-0.2170)5.53 (0.218)
EX6.600-6.615 (0.2598-0.2604)6.66 (0.262)
Stem-to-guide
clearance
IN0.010-0.037 (0.0004-0.0015)0.07 (0.003)
EX0.030-0.060 (0.0014-0.0024)0.11 (0.004)
Valve seat width0.9-1.1 (0.035-0.043)1.5 (0.06)
Valve guide pro-
jection height
IN19.4-19.6 (0.76-0.77)---
EX17.9-18.1 (0.70-0.71)---
Valve springFree lengthOUTERIN42.14 (1.659)40.58 (1.598)
EX42.83 (1.686)41.25 (1.624)
INNERIN38.11 (1.500)36.47 (1.436)
EX38.81 (1.765)37.51 (1.477)
Cylinder head warpage---0.10 (0.004)

Page 9-2

TORQUE VALUES

Cylinder head cover bolt10 N.m (1.0 kg-m, 7.2 ft-lb)
Camshaft holder8mm bolt23 N.m (2.3 kg-m, 17 ft-lb)
8mm nut23 N.m (2.3 kg-m, 17 ft-lb)
6mm bolt10 N.m (1.0 kg-m, 7.2 ft-lb)
Cylinder head10mm nut48 N.m (4.8 kg-m, 35 ft-lb)
8mm bolt23 N.m (2.3 kg-m, 17 ft-lb)
8mm nut23 N.m (2.3 kg-m, 17 ft-lb)
6mm bolt10 N.m (1.0 kg-m, 7.2 ft-lb)
Camshaft sprocket bolt10 N.m (1.0 kg-m, 7.2 ft-lb)
Cam chain tensioner bolt10 N.m (1.0 kg-m, 7.2 ft-lb)
Oil pass pipe7mm bolt10 N.m (1.0 kg-m, 7.2 ft-lb)
8mm bolt23 N.m (2.3 kg-m, 17 ft-lb)

TOOLS

Special
har har har... This section is not fun to look at or enter, just a bunch of numbers.
Maybe I'll put a jpg of the tool chart someday.

TROUBLESHOOTING

Engine top-end problems are usually performance-related and can usually be diagnosed by a compression test.
Engine noises can usually be traced to the top-end with a sounding rod or stethoscope.

Uneven or low compression

High compression Excessive noise Poor idling

Page 9-3

CYllNDER HEAD COVER REMOVAL

Remove the following parts: NOTE


FRONT:

Disconnect the spark plug caps.

Remove the cylinder head cover bolts and cover.

NOTE


REAR:

Disconnect the spark plug caps.
Remove the cylinder head cover bolts and cover.

CAMSHAFT REMOVAL

Remove the cylinder head covers (page 9-3) and carburetors (page 4-5).
Remove the timing hole cap and crankshaft hole cap from the left crankcase cover.
Align the FT mark (rear: RT mark) on the flywheel with the index mark on the left crankcase cover timing hole by turning the crankshaft counterclockwise.

Page 9-4


Make sure the piston is at TDC (TOP DEAD CENTER) on the compression stroke so the cam lobes are all facing down.

If the cam lobe is facing up at TDC, turn the crankshaft 360° couterclockwise, and re-align the mark and notch.
Pull wedge A straight up while holding wedge B down.
Secure wedge A with a 2 mm pin as shown.
Remove the camshaft holder on the cam sprocket side by removing the two mounting bolts.
Remove the cam sprocket bolt, rotate the crankshaft counterclockwise one turn (360°) and remove the other cam sprocket bolt.

NOTE

Remove the three camshaft holder mounting bolts and the nut, the oil plate and the holder.

Page 9-5


Remove the dowel pins.
Hang the cam chain on the camshaft behind the camshaft flange and remove the cam sprocket while lifting the camshaft out.

Attach a piece of wire to the cam chain to prevent it from being dropped into the crankcase.

INSPECTION

Cylinder head
Inspect the camshaft holder and cylinder head journal surfaces for scoring or evidence of insufficient lubrication.
Camshaft runout
Support both ends of the camshaft with V-blocks and check the camshaft runout with a dial indicator.

SERVICE LIMIT: 0.05 mm (0.002 in)


Using a micrometer, measure the height of each cam lobe.

SERVICE LIMIT:
   IN: 38.17 mm (1.503 in)
   EX: 38.19 mm (1.504 in)

Check the camshaft journals for wear or damage.
Measure the O.D. of each journal.

SERVICE LIMIT: 21.95 mm (0.864 in)

Page 9-6


Camshaft bearing oil clearance
Wipe any oil from the journals. Lay a strip of plastigauge lengthwise on top of each camshaft journal.

NOTE


Install the camshaft holders and tighten the mounting bolts in a crisscross pattern in 2 or 3 steps.

NOTE

TORQUE:
   6 mm flange bolt: 12 N.m (1.2 kg-m, 9 ft-lb)
   8 mm flange bolt: 23 N.m (2.3 kg-m, 17 ftlb)
   8 mm flange nut: 23 N.m (2.3 kg-m, 17 ft-lb)


Remove the camshaft holder and measure the width of each plastigauge. The widest thickness determines the oil clearance.

SERVICE LIMIT: 0.11 mm (0.004 in)

When the service limit is exceeded, replace the camshaft and recheck the oil clearance.

Replace the cylinder head and camshaft holder if the clearance still exceeds the service limit.


Camshaft holder/Rocker arm shaft/Rocker arm
Remove the rocker arm shafts by tapping the holder with a soft hammer.

Page 9-7


Remove the rocker arms and wave washers from the shafts.


Inspect the rocker arm shafts and rocker arms for wear or damage.

Check the rocker arms for clogged oil holes.

Measure the O.D. of each rocker arm shaft.

SERVICE LIMIT:
   IN/EX: 11.96 mm (0.471 in)

Measure the l.D. of each rocker arm.

SERVICE LIMIT: 12.03 mm (0.474 in)


CYLINDER HEAD

REMOVAL

NOTE

Drain the coolant (page 5-3) and remove the following:

California model only:
Remove the ASV pipes from the cylinder head.


Disconnect the clutch cable from the clutch lifter arm by removing the clutch cable holder bolt.
Remove the oil pipe from the engine.

NOTE

Remove the water pipes.