○Especially, apply a liquid gasket so that it shall be filled
up on the grooves [B].

○Do not apply liquid gasket to the inside of the groove
[C].

NOTICE
Do not apply liquid gasket around the crankshaft
main bearing inserts and oil passage holes.

CRANKSHAFT/TRANSMISSION 9-13
Crankcase Splitting

• Fit the lower crankcase to the upper crankcase.
○Make

NOTE

the application finish within 20 minutes when
the liquid gasket to the mating surface of the lower
crankcase half is applied.
○Moreover fit the case and tighten the bolts just after
application of the liquid gasket.
M9 bolts [A] have copper plated washers [B], replace
• The
them with new ones.
molybdenum disulfide oil solution to both sides [C]
• Apply
of the copper plated washer and threads [D] of the M9
bolts.

the lower crankcase bolts using the following
• Tighten
steps.

○Following the sequence numbers on the lower crankcase

half, tighten the M9 bolts [1  10] with copper plated washers.
Torque - Crankcase Bolts (M9): 44 N·m (4.5 kgf·m, 32 ft·lb)

○Replace the washer [A] with a new one.
○Tighten the M7 bolts.

Torque - Crankcase Bolts (M7): 20 N·m (2.0 kgf·m, 15 ft·lb)

L = 60 mm (2.36 in.) [B]
L = 50 mm (1.97 in.) [C]
L = 45 mm (1.77 in.) [D]

9-14 CRANKSHAFT/TRANSMISSION
Crankcase Splitting
the upper crankcase bolts using the following
• Tighten
steps.

○Tighten the M8 bolts [A].

Torque - Crankcase Bolts (M8): 27 N·m (2.8 kgf·m, 20 ft·lb)

○Replace the washer [B] with a new one.
○Tighten the M7 bolts.
L = 85 mm (3.35 in.) [C]
L = 50 mm (1.97 in.) [D]

Torque - Crankcase Bolts (M7): 20 N·m (2.0 kgf·m, 15 ft·lb)

○Tighten the M6 bolts.

L = 68 mm (2.69 in.) [E]
L = 40 mm (1.57 in.) [F]
Torque - Crankcase Bolts (M6): 12 N·m (1.2 kgf·m, 106 in·lb)

tightening all crankcase bolts, check the following
• After
items.

○Wipe

up the liquid gasket that seeps out around the
crankcase mating surface.
○Crankshaft and transmission shafts turn freely.
○While spinning the output shaft, gears shift smoothly from
the 1st to 6th gear, and 6th to 1st.
○When the output shaft stays still, the gear can not be
shifted to 2nd gear or other higher gear positions.
Install the removed parts (see appropriate chapters).

•

CRANKSHAFT/TRANSMISSION 9-15
Crankshaft and Connecting Rods
Crankshaft Removal

the crankcase (see Crankcase Splitting).
• Split
• Remove:
Connecting Rods (see Connecting Rod Removal)
Balancer [A] (see Balancer Removal)
Crankshaft [B]

Crankshaft Installation
NOTICE
If the crankshaft, bearing inserts, or crankcase
halves are replaced with new ones, select the bearing inserts and check clearance with a plastigage
(press gauge) before assembling engine to be sure
the correct bearing inserts are installed.
molybdenum disulfide oil solution to the crankshaft
• Apply
main bearing inserts.
the crankshaft with the camshaft chain [A] hanging
• Install
on it.
• Install the removed parts (see appropriate chapters).

Connecting Rod Removal

the crankcase (see Crankcase Splitting).
• Split
Remove:
• Connecting Rod Big End Nuts [A]
Connecting Rod Big End Caps [B]

NOTE

○Mark and record the locations of the connecting rods
and their big end caps so that they can be reassembled
in their original positions.

• Remove the connecting rods from the crankshaft.
NOTICE
Discard the connecting rod bolts. To prevent damage to the crankpin surfaces, do not allow the connecting rod bolts to bump against the crankpins.

9-16 CRANKSHAFT/TRANSMISSION
Crankshaft and Connecting Rods
Connecting Rod Installation
NOTICE
To minimize vibration, the connecting rods should
have the same weight mark.
Big End Cap [A]
Connecting Rod [B]
Weight Mark, Alphabet [C]
Diameter Mark [D]: “○” or no mark

NOTICE
If the connecting rods, big end bearing inserts, or
crankshaft are replaced with new ones, select the
bearing insert and check clearance with a plastigage (press gauge) before assembling engine to be
sure the correct bearing inserts are installed.
molybdenum disulfide oil solution [A] to the inner
• Apply
surfaces of upper and lower bearing inserts.
molybdenum disulfide grease to the connecting rod
• Apply
big end inside surface [B].
not apply any grease or oil to the cap inside and cap
• Do
insert outside [C].
the inserts so that their nails [D] are on the same
• Install
side and fit them into the recess of the connecting rod and
cap.

NOTICE
Wrong application of oil and grease could cause
bearing damage.

○When installing the inserts [A], be careful not to damage

•
•
•

the insert surface with the edge of the connecting rod [B]
or the cap [C]. One way to install inserts is as follows.
Installation [D] to Cap
Installation [E] to Connecting Rod
Push [F]
Spare Dowel Pin [G]
Connecting Rod Bolts [H]
Remove debris and clean the surface of inserts.
Install the cap on the connecting rod, aligning the weight
and diameter marks.
Apply molybdenum disulfide oil solution [MO] to the
threads and seating surfaces of the big end nuts and
bolts.

CRANKSHAFT/TRANSMISSION 9-17
Crankshaft and Connecting Rods
each connecting rod on its original crankpin.
•○Install
The connecting rod big end is bolted using the “plastic
region fastening method.”
method precisely achieves the needed clamping
force without exceeding it unnecessarily, allowing the
use of thinner, lighter bolts further decreasing connecting
rod weight.
○There are two types of the plastic region fastening. One is
a bolt length measurement method and other is a rotation
angle method. Observe one of the following two, but the
bolt length measurement method is preferable because
this is a more reliable way to tighten the big end nuts.

○This

NOTICE
The connecting rod bolts are designed to stretch
when tightened. Never reuse the connecting rod
bolts. See the table below for correct bolt and nut
usage.

NOTICE
Be careful not to overtighten the nuts.
The bolts must be positioned on the seating surface
correctly to prevent the bolt heads from hitting the
crankcase.
(1) Bolt Length Measurement Method
Be sure to clean the bolts, nuts, and connecting rods
thoroughly with a high flash-point solvent, because the
new connecting rods, bolts, and nuts are treated with an
anti-rust solution.

•

WARNING
Gasoline and low flash-point solvents can be
flammable and/or explosive and cause severe
burns. Clean the bolts, nuts, and connecting rods
in a well-ventilated area, and take care that there
are no sparks or flame anywhere near the working
area; this includes any appliance with a pilot light.
Do not use gasoline or a low flash-point solvent to
clean them.

NOTICE
Immediately dry the bolts and nuts with compressed air after cleaning.
Clean and dry the bolts and nuts completely.

9-18 CRANKSHAFT/TRANSMISSION
Crankshaft and Connecting Rods
new bolts and nuts in reused connecting rod.
• Install
If the connecting rod assy was replaced, use the bolts and

•

nuts attached to the new connecting rod assy.
Apply a small amount of molybdenum disulfide oil solution
to the following portions.
Threads [A] of Bolts and Nuts
Seating Surfaces [B] of Nuts and Connecting Rod Caps

both bolt head and bolt tip with a punch as shown.
• Dent
Before
use a point micrometer to measure the
• length oftightening,
new connecting rod bolts and record the values

•

to find the bolt stretch.
Connecting Rod [A]
Dent here with a punch [B].
Nuts [C]
Fit micrometer pins into dents [D].
Tighten the big end nuts until the bolt elongation reaches
the length specified in the table.
Bolt Length after
tightening

–

Connecting Rod
Assy

Bolt

New

Use the bolts
attached to
new con-rod.

Used

Replace the
bolts with new
ones.

Bolt Length before
=
tightening
Nut

Bolt Stretch

Usable Range of
Connecting Rod
Bolt Stretch

Attached to
new con-rod 0.20  0.32 mm
(0.0079  0.0126 in.)
New
Used
New

0.24  0.36 mm
(0.0094  0.0142 in.)

the length of the connecting rod bolts.
• Check
If the stretch is more than the usable range, the bolt has
stretched too much. An overelongated bolt may break in
use.

CRANKSHAFT/TRANSMISSION 9-19
Crankshaft and Connecting Rods
(2) Rotation Angle Method
If you do not have a point micrometer, you may tighten
the nuts using the “Rotation Angle Method.”
Be sure to clean the bolts, nuts and connecting rods thoroughly with a high flash-point solvent, because the new
connecting rods, bolts and nuts are treated with an anti
-rust solution.

•

WARNING
Gasoline and low flash-point solvents can be
flammable and/or explosive and cause severe
burns. Clean the bolts, nuts, and connecting rods
in a well-ventilated area, and take care that there
are no sparks or flame anywhere near the working
area; this includes any appliance with a pilot light.
Do not use gasoline or a low flash-point solvent to
clean them.

NOTICE
Immediately dry the bolts and nuts with compressed air after cleaning.
Clean and dry the bolts and nuts completely.
new bolts and nuts in reused connecting rods.
• Install
If the connecting rod assy was replaced, use the bolts and

•

nuts attached to the new connecting rod assy.
Apply a small amount of molybdenum disulfide oil solution
to the following portions.
Threads [A] of Bolts and Nuts
Seating Surfaces [B] of Nuts and Connecting Rod Caps

tighten the nuts to the specified torque. See the
• First,
table below.
tighten the nuts 120° ±5° .
•○Next,
Mark [A] the connecting rod big end caps and nuts so that
nuts can be turned 120° [B] properly.
○Tighten the hexagon nut by 2 corners.
Connecting
Rod Assy

Bolt

New

Use the bolts
attached to
new con-rod.

Nut
Attached to

Used

Replace the
bolts with new
ones.

Torque + Angle
N·m (kgf·m, ft·lb)
22 (2.2, 16)

new con-rod + 120°
New
Used
New

20 (2.0, 15)
+ 120°
26 (2.7, 19)
+ 120°
26 (2.7, 19)
+ 120°

9-20 CRANKSHAFT/TRANSMISSION
Crankshaft and Connecting Rods

○The nuts can be tightened by using a torque angle gauge
[A].

Crankshaft/Connecting Rod Cleaning

removing the connecting rods from the crankshaft,
• After
clean them with a high flash-point solvent.
the crankshaft oil passages with compressed air to
• Blow
remove any foreign particles or residue that may have
accumulated in the passages.

Connecting Rod Bend Inspection

the connecting rod big end bearing inserts, and
• Remove
reinstall the connecting rod big end cap.
an arbor [A] of the same diameter as the connect• Select
ing rod big end, and insert the arbor through the connect-

•
•
•

ing rod big end.
Select an arbor of the same diameter as the piston pin
and at least 100 mm (3.94 in.) long, and insert the arbor
[B] through the connecting rod small end.
On a surface plate, set the big-end arbor on V block [C].
With the connecting rod held vertically, use a height
gauge to measure the difference in the height of the
arbor above the surface plate over a 100 mm (3.94 in.)
length to determine the amount of connecting rod bend.
If the connecting rod bend exceeds the service limit, the
connecting rod must be replaced.
Connecting Rod Bend
Service Limit: TIR 0.2/100 mm (0.008/3.94 in.)

Connecting Rod Twist Inspection

the big-end arbor [A] still on V block [B], hold the
• With
connecting rod horizontally and measure the amount that
the arbor [C] varies from being paralleled with the surface
plate over a 100 mm (3.94 in.) length of the arbor to determine the amount of connecting rod twist.
If the connecting rod twist exceeds the service limit, the
connecting rod must be replaced.
Connecting Rod Twist
Service Limit: TIR 0.2/100 mm (0.008/3.94 in.)

CRANKSHAFT/TRANSMISSION 9-21
Crankshaft and Connecting Rods
Connecting Rod Big End Side Clearance
Inspection

connecting rod big end side clearance.
•○Measure
Insert a thickness gauge [A] between the big end and either crank web to determine clearance.
Connecting Rod Big End Side Clearance
Standard:
0.13  0.38 mm (0.0051  0.0150 in.)
Service Limit: 0.6 mm (0.02 in.)

If the clearance exceeds the service limit, replace the connecting rod with new one and then check clearance again.
If the clearance is too large after connecting rod replacement, the crankshaft also must be replaced.

Connecting Rod Big End Bearing Insert/Crankpin
Wear Inspection

the connecting rod big end (see Connecting Rod
• Remove
Removal).
strips of plastigage (press gauge) to crankpin width.
• Cut
Place a strip on the crankpin parallel to the crankshaft

•

installed in the correct position.
Tighten the connecting rod big end nuts to the specified
torque (see Connecting Rod Installation).

NOTE

○Do not move the connecting rod and crankshaft during
clearance measurement.
the connecting rod big end again, measure each
• Remove
clearance between the bearing insert and crankpin [A] using plastigage (press gauge) [B].

NOTICE
After measurement, replace the connecting rod
bolts.
Connecting Rod Big End Bearing Insert/Crankpin Clearance
Standard:
0.030  0.060 mm (0.0012  0.0024 in.)
Service Limit: 0.10 mm (0.0039 in.)

If the clearance is within the standard, no bearing replacement is required.
If the clearance is between 0.061 mm (0.0024 in.) and
the service limit (0.10 mm, 0.0039 in.), replace the bearing inserts [A] with inserts painted blue [B]. Check insert/crankpin clearance with the plastigage. The clearance may exceed the standard slightly, but it must not be
less than the minimum in order to avoid bearing seizure.
If the clearance exceeds the service limit, measure the
diameter of the crankpins.
Crankpin Diameter
Standard:
34.484  34.500 mm (1.3576  1.3583 in.)
Service Limit: 34.47 mm (1.357 in.)

9-22 CRANKSHAFT/TRANSMISSION
Crankshaft and Connecting Rods
If any crankpin has worn past the service limit, replace the
crankshaft with a new one.
If the measured crankpin diameters [A] are not less than
the service limit, but do not coincide with the original diameter markings [B] on the crankshaft, make new marks
on it.
Crankpin Diameter Marks
None
34.484  34.492 mm (1.3576  1.35795 in.)

○

34.493  34.500 mm (1.35799  1.3583 in.)

: Crankpin Diameter Marks, “○” or no mark.

CRANKSHAFT/TRANSMISSION 9-23
Crankshaft and Connecting Rods
the connecting rod big end inside diameter, and
• Measure
mark each connecting rod big end in accordance with the

•

inside diameter.
Tighten the connecting rod big end nuts to the specified
torque (see Connecting Rod Installation).

NOTE

○The mark already on the big end should almost coincide
with the measurement.
Connecting Rod Big End Inside Diameter Marks
None
37.500  37.508 mm (1.4764  1.47669 in.)

○

37.509  37.516 mm (1.47673  1.4770 in.)

Big End Cap [A]
Connecting Rod [B]
Weight Mark, Alphabet [C]
Diameter Mark (Around Weight Mark) [D]: “○” or no
mark
the proper bearing insert [A] in accordance with the
• Select
combination of the connecting rod and crankshaft coding.
Size Color [B]
Con-rod Big End
Inside Diameter
Marking

Crankpin
Diameter
Marking

Size Color

Part Number

None

○

Brown

92139-0124

None

None

○
○

○

Black

92139-0123

None