73.374  73.384 mm (2.8887  2.8891 in.)
0.010  0.032 mm (0.0004  0.0013 in.)

73.49 mm (2.893 in.)
73.22 mm (2.883 in.)
– – –

0.035  0.070 mm (0.00138  0.00276 in.)
0.020  0.055 mm (0.00079  0.00217 in.)

0.17 mm (0.0067 in.)
0.16 mm (0.0063 in.)

0.82  0.84 mm (0.0323  0.0331 in.)
0.81  0.83 mm (0.0319  0.0327 in.)

0.92 mm (0.0362 in.)
0.91 mm (0.0358 in.)

0.770  0.785 mm (0.0303  0.0309 in.)
0.775  0.790 mm (0.0305  0.0311 in.)

0.70 mm (0.028 in.)
0.71 mm (0.028 in.)

0.15  0.25 mm (0.0059  0.0098 in.)
0.30  0.40 mm (0.0118  0.0157 in.)

0.6 mm (0.02 in.)
0.7 mm (0.03 in.)

5-10 ENGINE TOP END
Special Tools and Sealants
Compression Gauge, 20 kgf/cm²:
57001-221

Valve Seat Cutter, 32° 57001-1118

25:

Valve Spring Compressor Assembly:
57001-241

Valve Seat Cutter, 32° 57001-1119

28:

Piston Pin Puller Assembly:
57001-910

Valve Seat Cutter Holder Bar:
57001-1128

Valve Seat Cutter, 45° 57001-1114

27.5:

Valve Spring Compressor Adapter,
57001-1202

Valve Seat Cutter, 45° 57001-1115

32:

Valve Seat Cutter Holder,
57001-1330

4.5:

22:

ENGINE TOP END 5-11
Special Tools and Sealants
Valve Guide Arbor,
57001-1331

4.5:

Valve Guide Reamer,
57001-1333

Valve Guide Driver:
57001-1564

4.5:

Valve Spring Compressor Adapter,
57001-1586

Valve Seat Cutter, 60° 57001-1334

33:

Washer:
57001-1612

Valve Seat Cutter, 60° 57001-1409

27:

Liquid Gasket, TB1211F:
92104-0004

Compression Gauge Adapter, M10 × 1.0:
57001-1486

Liquid Gasket, TB1216B:
92104-1064

24:

5-12 ENGINE TOP END
Clean Air System
Air Suction Valve Removal

• Remove:
Air Switching Valve (see Air Switching Valve Removal)
Air Suction Valve Cover Bolts [A] (Both Sides)
Bracket
Air Suction Valve Cover [B] (Both Sides)

• Remove the air suction valve [A] on both sides.

Air Suction Valve Installation

the air suction valve so that opening [A] of the reed
• Install
faces the front and downward.

the bracket [A] as shown.
• Install
the air suction valve covers.
• Install
Apply
a
non-permanent locking agent to the threads of
• the air suction
valve cover bolts [B], and tighten them.
Torque - Air Suction Valve Cover Bolts: 9.8 N·m (1.0 kgf·m,
87 in·lb)

• Install the removed parts (see appropriate chapters).

ENGINE TOP END 5-13
Clean Air System
Air Suction Valve Inspection

the air suction valve (see Air Suction Valve Re• Remove
moval).
inspect the reeds [A] for cracks, folds, warps,
• Visually
heat damage or other damage.

•

If there is any doubt as to the condition of the reeds, replace the air suction valve as an assembly.
Check the reed contact areas [B] of the valve holder for
grooves, scratches, any signs of separation from the
holder or heat damage.
If there is any doubt as to the condition of the reed contact
areas, replace the air suction valve as an assembly.
If any carbon or other foreign particles have accumulated
between the reed and the reed contact area, wash the
valve assembly clean with a high flash-point solvent.

NOTICE
Do not scrape off the deposits with a scraper as this
could damage the rubber, requiring replacement of
the suction valve assembly.

Air Switching Valve Removal
NOTICE
Never drop the air switching valve especially on a
hard surface. Such a shock to the air switching
valve can damaged it.
the air cleaner housing (see Air Cleaner Housing
• Remove
Removal in the Fuel System (DFI) chapter).
the connector [A].
• Disconnect
Disconnect
the hoses [B] from the air suction valve cov• ers, and remove
the air switching valve [C].

Air Switching Valve Installation

the air switching valve [A] with hoses as shown.
• Install
Left Side View [B]

•

About 40° [C]
Install the removed parts (see appropriate chapters).

Air Switching Valve Operation Test

to the Air Suction System Damage Inspection in the
• Refer
Periodic Maintenance chapter.

Air Switching Valve Unit Test

to the Air Switching Valve Unit Test in the Electrical
• Refer
System chapter.

5-14 ENGINE TOP END
Clean Air System
Clean Air System Hose Inspection

certain that all the hoses are routed without being flat• Be
tened or kinked, and are connected correctly to the air
cleaner housing, air switching valve and air suction valve
covers.
If they are not, correct them. Replace them if they are
damaged.

ENGINE TOP END 5-15
Cylinder Head Cover
Cylinder Head Cover Removal

• Remove:
Air Suction Valves (see Air Suction Valve Removal)
•

Stick Coils (see Stick Coil Removal in the Electrical System chapter)
Radiator (see Radiator and Radiator Fan Removal in the
Cooling System)
Remove the clamp [A] from heat insulation plate.

• Remove:
Quick Rivet [A] (Both Side)
Heat Insulation Rubber Plate [B]

• Remove:
Cylinder Head Cover Bolts [A] with Washers
Cylinder Head Cover [B]
Heat Insulation Plate
Gasket

Cylinder Head Cover Installation

the plug hole gaskets [A] with new ones.
• Replace
Install:
• Dowel Pins [B]
Plug Hole Gaskets

a high flash-point solvent, clean off any oil or dirt
• Using
that may be on the liquid gasket coating area. Dry them

•

with a clean cloth.
Apply liquid gasket [A] to the cylinder head as shown.
Sealant - Liquid Gasket, TB1216B: 92104-1064

NOTE

○Make the application finish within 20 minutes with the
liquid gasket (TB1216B) to the mating surface of the
cylinder head cover is applied.

5-16 ENGINE TOP END
Cylinder Head Cover
the head cover gasket with a new one.
• Replace
Using
a
high
solvent, clean off any oil or dirt
• that may be onflash-point
the liquid gasket coating area. Dry them

•

with a clean cloth.
Apply liquid gasket around the groove [A] on the sealing
surface to retain the gasket in the cylinder head cover.
Sealant - Liquid Gasket, TB1211F: 92104-0004

• Install the gasket to the cylinder head cover.
the washers with new ones.
• Replace
Install
the
washers with the metal side [A] faces upward.
•

the cylinder head cover bolts following the speci• Tighten
fied tightening sequence [1  6].
Torque - Cylinder Head Cover Bolts: 10 N·m (1.0 kgf·m, 89
in·lb)

• Install the removed parts (see appropriate chapters).

ENGINE TOP END 5-17
Camshaft Chain Tensioner
Camshaft Chain Tensioner Removal
NOTICE
This is a non-return type camshaft chain tensioner.
The push rod does not return to its original position
once it moves out to take up camshaft chain slack.
Observe all the rules listed below.
When removing the tensioner, do not take out the
mounting bolts only halfway. Retightening the
mounting bolts from this position could damage
the tensioner and the camshaft chain. Once the
bolts are loosened, the tensioner must be removed
and reset as described in “Camshaft Chain Tensioner Installation.”
Do not turn over the crankshaft while the tensioner
is removed. This could upset the camshaft chain
timing, and damage the valves.

• Remove:
Camshaft Chain Tensioner Cap Bolt [A]
Washer [B]
Spring [C]
Rod [D]
Camshaft Chain Tensioner Mounting Bolts [E]
Camshaft Chain Tensioner Body [F]

Camshaft Chain Tensioner Installation

the O-ring [A] with a new one.
• Replace
Apply
grease
to the new O-ring.
• Release the stopper
[B] and push the push rod [C] into
• the interior of the tensioner
body [D].
Install
the
tensioner
body
so
that the stopper faces up• ward.

• Tighten:
Torque - Camshaft Chain Tensioner Mounting Bolts [A]: 11
N·m (1.1 kgf·m, 97 in·lb)

the rod, spring and washer.
• Install
Tighten:
•
Torque - Camshaft Chain Tensioner Cap Bolt [B]: 20 N·m
(2.0 kgf·m, 15 ft·lb)

the crankshaft 2 turns clockwise to allow the ten• Turn
sioner to expand and recheck the camshaft chain timing.

5-18 ENGINE TOP END
Camshaft, Camshaft Chain
Camshaft Removal

• Remove:
Cylinder Head Cover (see Cylinder Head Cover Re•

moval)
Crankshaft Sensor Cover (see Crankshaft Sensor Removal in the Electrical System chapter)
Using a wrench on the timing rotor bolt [A], turn the crankshaft clockwise until the line [B] (TDC mark for #1, 4 pistons) on the timing rotor is aligned with the mating surface
[C] of the crankcase.

the camshaft chain tensioner (see Camshaft
• Remove
Chain Tensioner Removal).
the upper camshaft chain guide bolts and
• Loosen
camshaft cap bolts gradually and evenly as shown se-

•
•

quence [1  20], and remove them.
Remove:
Upper Camshaft Chain Guide [A]
Camshaft Caps [B]
Camshafts [C]
Stuff a clean cloth into the chain tunnel to keep any parts
from dropping into the crankcase.

• Remove:
Camshaft Sprocket Mounting Bolts [A]
Camshaft Sprockets [B]

NOTICE
The crankshaft may be turned while the camshafts
are removed. Always pull the chain taut while turning the crankshaft. This avoids kinking the chain
on the lower (crankshaft) sprocket. A kinked chain
could damage both the chain and the sprocket.

ENGINE TOP END 5-19
Camshaft, Camshaft Chain
Camshaft Installation

sure to install the following parts.
• BePlug
Hole Gaskets [A]
Dowel Pins [B]

NOTE

○The exhaust camshaft has a 8943 EX mark [A] and the
intake camshaft has a 8943 IN mark [B]. Be careful not
to mix up these shafts.

the camshaft sprockets so that position the timing
• Install
marks [A] outside.

○The

•

intake camshaft sprocket and exhaust camshaft
sprocket are identical.
Apply a non-permanent locking agent to the threads of
the camshaft sprocket bolts and tighten them.
Torque - Camshaft Sprocket Bolts: 15 N·m (1.5 kgf·m, 11
ft·lb)

molybdenum disulfide oil solution to all cam parts
• Apply
and journals.
a wrench on the timing rotor bolt [A], turn the crank• Using
shaft clockwise until the line [B] (TDC mark for #1,4 pistons) on the timing rotor is aligned with the mating surface
[C] of the crankcase.

NOTICE
The crankshaft may be turned while the camshafts
are removed. Always pull the chain taut while turning the crankshaft. This avoids kinking the chain
on the lower (crankshaft) sprocket. A kinked chain
could damage both the chain and the sprocket.

5-20 ENGINE TOP END
Camshaft, Camshaft Chain
the tension side (exhaust side) [A] of the chain taut
• Pull
to install the chain.
the camshaft chain with the sprockets so that tim• Engage
ing marks on the sprockets are positioned as shown.

○The timing marks must be aligned with the cylinder head
upper surface [B].
EX mark [C]
IN mark [D]
#1 pin [E]
#2 pin [F]
#30 pin [G]
#31 pin [H]

ENGINE TOP END 5-21
Camshaft, Camshaft Chain
installing the camshaft caps and upper chain
• Before
guide, install the camshaft chain tensioner body tem-

•
•

porarily (see Camshaft Chain Tensioner Installation).
Install the camshaft caps and upper camshaft chain guide
[A] as shown.
Identification No. 1  4 (Camshaft Cap) [B]
First tighten the all camshaft cap bolts and upper
camshaft chain guide bolts evenly to seat the camshaft
in place, then tighten all bolts following the specified
tightening sequence.
Torque - Camshaft Cap Bolts [1  18]: 12 N·m (1.2 kgf·m,
106 in·lb)
Upper Camshaft Chain Guide Bolts [19, 20]: 12
N·m (1.2 kgf·m, 106 in·lb)

the camshaft chain tensioner (see Camshaft Chain
• Install
Tensioner Installation).
the crankshaft 2 turns clockwise to allow the ten• Turn
sioner to expand and recheck the camshaft chain timing.
• Install the removed parts (see appropriate chapters).

5-22 ENGINE TOP END
Camshaft, Camshaft Chain
Camshaft, Camshaft Cap Wear Inspection

• Remove:
Camshaft Caps (see Camshaft Removal)
Cut
of plastigage (press gauge) to journal width.
• Placetheastrips
strip on each journal parallel to the camshaft in•

stalled in the correct position.
Tighten the camshaft cap bolts and upper camshaft chain
guide bolts to the specified torque (see Camshaft Installation).

NOTE

○Do not turn the camshaft when the plastigage is between the journal and camshaft cap.
the camshaft cap again, measure each clear• Remove
ance between the camshaft journal and the camshaft cap
using plastigage [A].
Camshaft Journal, Camshaft Cap Clearance
Standard:
0.038  0.081 mm (0.0015  0.0032 in.)
Service Limit: 0.17 mm (0.0067 in.)

If any clearance exceeds the service limit, measure the
diameter of each camshaft journal with a micrometer.
Camshaft Journal Diameter
Standard:
23.940  23.962 mm (0.94252  0.94338
in.)
Service Limit: 23.91 mm (0.9413 in.)

If the camshaft journal diameter is less than the service
limit, replace the camshaft with a new one and measure
the clearance again.
If the clearance still remains out of the service limit, replace the cylinder head unit.

Camshaft Runout Inspection

the camshafts (see Camshaft Removal).
• Remove
Set
the
camshaft
in a camshaft alignment jig or on V
• blocks.
the runout with a dial gauge [A] at the specified
• Measure
place as shown.
If the runout exceeds the service limit, replace the
camshaft.
Camshaft Runout
Standard:
TIR 0.02 mm (0.0008 in.) or less
Service Limit: TIR 0.1 mm (0.004 in.)

ENGINE TOP END 5-23
Camshaft, Camshaft Chain
Cam Wear Inspection

the camshafts (see Camshaft Removal).
• Remove
the height [A] of each cam with a micrometer.
• Measure
If the cams are worn down past the service limit, replace
the camshaft.
Cam Height
Standard:
Exhaust

33.743  33.857 mm (1.3285  1.3330 in.)

Intake

34.443  34.557 mm (1.3560  1.3605 in.)

Service Limit:
Exhaust

33.64 mm (1.324 in.)

Intake

34.34 mm (1.352 in.)

Camshaft Chain Removal

the crankcase (see Crankcase Splitting in the Crank• Split
shaft/Transmission chapter).
the camshaft chain [A] from the crankshaft
• Remove
sprocket.

Camshaft Chain Installation

the camshaft chain to the crankshaft sprocket.
• Install
the crankcase (see Crankcase Assembly in the
• Assemble
Crankshaft/Transmission chapter).

5-24 ENGINE TOP END
Cylinder Head
Cylinder Compression Measurement
NOTE