Engine Specifications

1.

a. b.

Cylinder

Head Volume
Warp Limit

31.5 - 32.3 cm³ (1.92 - 1.97 cu.in)
<0.03 mm (0.0012 in)>
Lines indicate straightedge measurement

2. a. b. c. d.

Cylinder
Material
Bore Size
Taper Limit
Out-of-round Limit

Aluminum alloy with cast iron sleeve
67.0 mm (2.638 in)
<0.05 mm (0.0020 in)>
<0.01 mm (0.0004 in)>

3.
a.

b. c. d.

Camshaft
Drive Method

Cam Cap Inside Diameter
Camshaft Outside Diameter
Shaft-to-cap Clearance

e.

Cam Dimensions

Intake

"A"
"B"
"C"

36.75 - 36.85 mm (1.447 - 1.451 in)
28.05 - 28.15 mm (1.104 - 1.108 in)
8.75 — 8.85 mm (0.344 — 0.348 in)

Exhaust

"A"
"B"
"C"

36.25 — 36.35 mm (1.427 — 1.431 in)
28.55 - 28.65 mm (1.124 - 1.128 in)
8.25 — 8.35 mm (0.325 - 0.329 in)

f.

Open
Close

Open
Close

B.T.D.C. 38°
A.B.C.D. 58°

B.B.D.C. 66°
A.T.D.C. 26°

Overlap

a = 64°

g.

h. i.

Cam Chain Type/Number of Links
Cam Chain Adjustment Method

BUSH-CHAIN/120
Automatic

4.
a.

b.

Valve, Valve Seat, Valve Guide
Valve Clearance (Cold)                        INTAKE.
                                                        EXHAUST.

Valve Dimensions

0.11 — 0.15 mm (0.0043 - 0.0059 in)
0.16 — 0.20 mm (0.0063 — 0.0079 in)

"A" Head Dia.               IN.
                                  EX.
"B" Face Width              IN.
                                  EX.
"C" Seat Limit Width      IN.
                                  EX.

36.1 ± 0.1 mm (1.42 ± 0.004 in)
30 ± 0.1 mm (1.18 ± 0.004 in)
2.3 mm (0.091 in)
2.3 mm (0.091 in)
1 ± 0.1 mm (0.039 ± 0.004 in)
1 ± 0.1 mm (0.039 ± 0.004 in)

"D" Margin Thickness Limit IN.
                                      EX.

0.7 mm (0.028 in)
0.7 mm (0.028 in)

c.

Stem Outside Diameter IN.

7^-0.10_-0.025mm (0.2756 ^-0.0004_-0.0010 in)

                                  EX.

7^-0.25_-0.040 mm (0.2756 ^-0.0010_-0.0016 in),

d

Guide Inside Diameter   IN.

7^+0.12_-0. mm (0.2756 ^-0.0005_-0.in)

                                   EX.

7^+0.12_-0. mm (0.2756 ^-0.0005_-0. in)

e.

Stem-to-guide Clearance IN.

0.010 — 0.037 mm (0.0004 - 0.0015 in)

                                    EX.

0.025 — 0.052 mm (0.0010 - 0.0020 in)

f.

Stem Runout Limit

<0.03 mm (0.0012 in)>

g-

Valve Seat Width Standard <Limit>

0.9 - 1.1 mm (0.035 - 0.043 in)
<2.0 mm (0.080 in)>

5.

a.

Valve Spring Free Length
Inner Spring              IN.
                               EX.
Outer Spring              IN.
                               EX.

35.9 mm (1.413 in)
35.9 mm (1.413 in)
39.5 mm (1.555 in)
39.5 mm (1.555 in)

b.

Spring rate
Inner Spring              IN.

                               EX.

K, : 2.36 kg/mm (132 lb/in)
K₂ : 1.84 kg/mm (103 lb/in)
K, : 2.36 kg/mm (132 lb/in)
K₂ : 1.84 kg/mm (103 lb/in)

Outer Spring              IN.
                               EX.

K, : 4.58 kg/mm (256 lb/in)
K₂ : 3.464 kg/mm (194 lb/in)
K, : 4.58 kg/mm (256 lb/in)
K₂ : 3.464 kg/mm (194 lb/in)

c.

Compression Length (Valve Closed)
Inner Spring              IN.
                               EX.
Outer Spring              IN.
                               EX.

31.0 mm (1.220 in) 3
31.0 mm (1.220 in)
34.0 mm (1.339 in)
34.0 mm (1.339 in)

d.

Compression Force (Valve Closed) Inner Spring                      IN.
                               EX.
Outer Spring              IN.
                               EX.

8.1 - 9.9 kg (17.9 - 21.8 lb)
8.1 - 9.9 kg (17.9 - 21.8 lb)
17.6 — 20.6 kg (38.8 — 45.4 lb)
17.6 — 20.6 kg (38.8 — 45.4 lb)

e.

Tilt Limit


Inner Spring IN. & EX.
Outer Spring IN. & EX.

2.5°  1.7 mm (0.067 in)
2.5°  1.7 mm (0.067 in)

f.

Direction of Winding (Top View)

Intake

Exhaust

6.

a.

Piston Piston Size/Measuring Point (A)

67.0 mm (2.638 in)/7.8 mm (0.307 in)
(From bottom line of piston skirt)

b.

c.

d.

Clearance between Piston & Cylinder
Limit
Oversize                   1 st
                               2nd
                               3rd
                               4th
Piston Pin Hole Off-Set

0.03 - 0.05 mm (0.0012 - 0.0020 in)
<0.1 mm (0.0039 in)>
 -
67.50 mm (2.667 in)
-
68.00 mm (2.677 in)
0.5 mm (0.02 in) Inside

7.
a.

Piston Ring
Sectional Sketch

Top Ring

B = 1.2^-0.01_-0.03 mm (0.47^-0.0004_-0.0012in)
T = 2.7 ± 0.1 mm (0.106 ± 0.004 in)

2nd Ring

B = 1.2^-0.01_-0.03 mm (0.472^-0.0004_{-0.0012 in})
T = 2.7 ± 0.1 mm (0.106 ± 0.004 in),

Oil Ring

B = 2.5 mm (0.098 in)

T = 2.8 ± 0.15 mm (0.110 ± 0.0059 in)

b.

End Gap (Installed) Limit

Top Ring

2nd Ring

Oil Ring

0.15 - 0.35 mm (0.0059 - 0.0138 in)
<1.0 mm (0.039 in)>
0.15 - 0.35 mm (0.0059 - 0.0138 in)
< 1.0 mm (0.039 in)>
0.3 - 0.9 mm (0.012 - 0.035 in)
< 1.5 mm (0.059 in)>

c

Side Clearance
Limit

Top Ring

2nd Ring

0.03 - 0.07 mm (0.0012 - 0.0028 in)
<0.15 mm (0.0059 in)>
0.02 — 0.06 mm (0.0008 — 0.0024 in)
<0.15 mm (0.0059 in)>

d.

Plating or Coating

Top Ring
2nd Ring
Oil Ring

Chrome plated, Ferox coating
Parkerizing
Chrome plated, Ferox coating

8.
a.
b.

Connecting Rod
Oil Clearance
Color Code

0.016 - 0.040 mm (0.0006 - 0.0016 in)
1. Blue, 2. Black, 3. Brown, 4. Green

9. a.

b. c. d. e.

Crankshaft
Crank Width "A"

Assembly Width "B"

Deflection Limit "C"
Big End Side Clearance "D"

Journal Oil Clearance

A, = 56.15 mm (2.211 in)
A₂ = 59.20 mm (2.331 in)
A₃ = 60.45 mm (2.380 in)
A₄ = 56.45 mm (2.222 in)
341.4 ± 0.6 mm
(13.44 ± 0.024 in)
<0.03 mm (0.0012 in)>
0.16 - 0.26 mm
(0.0063 - 0.0102 in)
0.020 - 0.044 mm (0.0008 - 0.0017 in)

f.

Color Code - Corresponding Size                                Blue

1.5^+0.006_+0.002mm(0.0591^+0.00024_+0.00008in

Black

1.5^+0.002_-0.002mm(0.0591^+0.00008_-0.00008in)

Brown

1.5^-0.002_-0.006mm(0.0591^-0.00008_-0.00024in)

Green

1.5^-0.006_-0.010mm(0.0591^-0.00024_-0.00039in)

Yellow

1.5^-0.010_-0.014mm(0.0591^-0.00039_-0.00055in)

10. a. b.

c. d.

e.
f.

g
h.

i.

j-

Clutch
Friction Plate Thickness/Quantity
Wear Limit

Clutch Plate Thickness/Quantity
Warp Limit

Clutch Spring Free Length/Quantity
Minimum Length

Primary Reduction Gear Backlash Tolerance
Primary Drive Gear
Backlash Number
Primary Driven Gear
Backlash Number
Clutch Release Method

3.0 ± 0.1 mm (0.12 ± 0.004 in)/8
<2.8 mm (0.11 in)>

2.0 ± 0.1 mm (0.080 ± 0.004 in)/7
<0.05 mm (0.002 in)>

44.0 mm (1.73 in)/5
43.0 mm (1.69 in)

116

87 - 93

25 — 31
Rack & Pinion pull, Outer pull

11. a.

Transmission
Main Axle Run-out Limit

<0.08 mm (0.0031 in)>

12
a.

Shifter
Shifter Type

Guide bar

13. a. b. c. d.

Carburetor
Type/Manufacturer/Quantity
I.D. Mark
Throttle Valve Size
Venturi Size

BS35/MIKUNI/4
31A 00
ø35 mm (01.38 in)
ø31 mm (01.22 in)

e.

f.

g

h.

i.

j-

k.

I.

m.

n.

o.

P-

q-

Main Jet

Main Air Jet

Jet Needle

Needle Jet

Throttle Valve

Pilot Jet

Pilot Air Jet

Pilot Screw (turns out)

Pilot Outlet Size

Starter Jet

Valve Seat Size

Fuel Level

Float Height

(MJ.)

(M.A.J.)

(J.N.)

(N.J.)

(Th.V.)

(P.J.)

(P.A.J.)

(P.S.)

(P.O.)

(G.S.)

(V.S.)

(F.L)

(F.H.)

#102.5

#45

4HZ26-3

Y-0 (#318)

135

#40

#160

Pre-set 2 turns

00.8

#32.5

Φ2.0

5 ± 1 mm (0.20 ± 0.04 in)

22.3 ± 0.5 mm (0.9 ± 0.02 in)

r.

s.

Engine Idling Speed

Vacuum Pressure at Idling Speed

1,100 ± 50 r/min

225 - 235 mmHg (8.85 — 9.25 inHg)

14.
a.
b.
c.
d.
e.
f.

g-

Lubrication System:
Oil Filter Type
Oil Pump Type
Tip Clearance
Side Clearance
Bypass Valve Setting Pressure
Relief Valve Operating Pressure

Lubrication Diagram

Paper filter
Trochoid pump
0.03 — 0.09 mm (0.0012 — 0.0035 in)
0.03 — 0.08 mm (0.0012 — 0.0031 in)
98 ± 20 kPa (1.0 ± 0.2 kg/cm². 14.2 ± 2.8 psi)
490 ± 50 kPa (5.0 ± 0.5 kg/cm². 71.1 ± 7.1 psi)

15.

Middle Gear Backlash

0.1 - 0.2 mm (0.004 ~~ 0-008 in)

16.

Final Gear Backlash

0.1 — 0.2 mm (0.004 - 0.008 in)

17.

Crankcase Tightening Sequence

LOWER CASE

UPPER CASE

Tightening Torque:

 8 mm bolt: 24 Nm (2.4 mkg. 1 7 ft-lb)  6 mm bolt: 12 Nm (1.2 mkg, 8.7 ft-lb)

18.

Tightening Torque

Part to be tightened

Part name

Thread size

Q'ty

Tightening torque

Remarks

Nm

mkg

ft lb

ENGINE:

Camshaft cap

Bolt

M6x1.0

24

10     1.0    7.2

Tighten in stages

Cam chain (Front) (Rear)

Stud bolt Nut

Stud bolt Nut

M6x1.0
M6x1.0
M6x1.0
M6x1.0

2
2
2 2

5 0.    5         3.6

10      1.0      7.2
5       0.5       3.6
10      1.0      7.2

Apply oil Apply oil

Exhaust pipe

Stud bolt

M6x1.0

8

8       0.8       5.8

Apply oil

Oil passage blind plug

Screw

M6x1.0

1

7       0.7       5.1

YICS passage

Stud bolt
Nut
Blind plug

M8x1.25
M8x1.25
M12x1.25

2

2 2

15      1.5       11
20      2.0       14
22      2.2       16

Apply oil

Spark plug

—

M14X1.25

4

20      2.0       14

Cylinder head

Nut

M10x1.25

12

32      3.2       23

Apply oil

Cylinder head cover

Bolt

M6x1.0

8

10      1.0      7.2

Cam chain (Cylinder-Front)

Stud bolt

Nut

M8x1.25
M8x1.25

1

1

8        0.8      5.8
20      2.0       14

Apply oil

Connecting rod

Nut

M8x0.75

8

38      3.8       27

Cam sprocket

Bolt

M7x1.0

4

20      2.0       14

Cam chain tensioner

Bolt

M6x1.0

2

10      1.0      7.2

Cam chain tensioner guide

Bolt

M8x1.25

1

3        0.3     2.2

Oil Pump cover

Screw

M6x1.0

4

7        0.7      5.1

Strainer housing

Screw

M6x1.0

3

7        0.7      5.1

Oil pump

Bolt

M6x1.0

3

12      1.2      8.7

Oil filter

Union bolt

M20x1.5

1

15      1.5      11

Engine drain bolt

Bolt

M14x1.5

1

43      4.3      31

Strainer cover

Bolt

M6x1.0

13

12      1.2      8.7

Oil pump sprocket

Bolt

M6x1.0

1

12      1.2      8.7

Buffle plate

Screw

M6x1.0

3

7        0.7      5.1

Oil cooler adapter plate

Union bolt

M20x1.5

1

50      5.0       36

Part to be tightened

Part name

Thread size

Q'ty

Tightening torque

Remarks

Nm

mkg

ft-lb

Oil cooler hose and adapter

Bolt

M6x1.0

4

12

1.2

8.7

Oil hose

Bolt

M6x1.0

1

12

1.2

8.7

Oil cooler

Bolt

M6x1.0

3

10

1.0

7.2

Oil cooler hose clamp

Nut

M8x1.25

1

10

1.0

7.2

Carburetor joint

Bolt

M6x1.0

8

12

1.2

8.7

Air filter case cover

Screw

M6xt.O

4

5

0.5

3.6

Air filter case and frame

Bolt

M6x1.0

3

5

0.5

3.6

Exhaust pipe joint band

Bolt

M8x1.25

6

20

2.0

14

Exhaust pipe ring nut

Nut

M6x1.0

8

10

1.0

7.2

Exhaust pipe and frame

Bolt

M1 0x1.25

2

25

2.5

18

Cylinder

Stud bolt Bolt

M10x1.25 M10X1.25

8

4

20 20

2.0 2.0

14

14

Crankcase

Bolt Bolt

M8x1.25 M6x1-0

19

19

24

12

2.4 1.2

17 8.7

Bearing plate stopper

Screw

M8x1.25

4

25

2.5

18

Breaker cover

Screw

M6x1.0

8

8

0.8

5.8

Generator cover .

Bolt

M6x1.0

3

12

1.2

8.7

Generator housing bearing

Screw

M6x1.0

3

10

1.0

7.2

Change cover

Bolt

M6x1.0

10

12

1.2

8.7

Drive shaft housing bearing

Bolt

M6x1.0

3

12

1.2

8.7

Clutch cover

Bolt

M6x1.0

10

12

1.2

8.7

Clutch cable holder

Bolt

M6x1.0

2

12

1.2

8.7

Middle drain bolt

Bolt

M8x1.25

1

16

1.6

11

Breather pipe 1

Screw

M6x1.0

3

7

0.7

5.1

Breather pipe 2

Screw

M6x1.0

4

7

0.7

5.1

Main gallary blind plug

Plug

M20X1.5

2

12

1.2

8.7

Apply oil

Stopper plate

Bolt

M6x1.0

1

10

1.0

7.2

Clutch starter outer

Bolt

M8x1.25

3

25

2.5

18

Upper guide

Bolt

M6x1.0

3

10

1.0

7.2

Clutch pressure plate

Bolt

M6x1.0

5

8

0.8

5.8

Clutch boss

Nut

M20X1.0

1

70

7.0

50

Drive shaft bearing

Nut

M34x1.0

1

110

11.0

80

Part to be tightened

Part name

Thread size

Q'ty

Tightening torque

Remarks

Nm

mkg

ft ib

Driven shaft bearing

Nut

M65x1.5

1

110

11.0

80

Middle gear flange

Nut

M14x1.5

1

90

9.0

65

Housing bearing

Bolt

M8x1.25

4

25

2.5

18

Stopper plate

Screw Bolt

M6x1.0 M6x1.0

1

1

7 8

0.7 0.8

5.1 5.8

Change pedal

Bolt

M6x1.0

1

10

1.0

7.2

Change pedal link

Nut

M6x1.0

2

10

1.0

7.2

A.C. Generator

Bolt

M10x1.25

1

55

5.5

40

Pick-up coil base

Screw

M6x1.0

2

8

0.8

5.8

Rotor

Bolt

M8x1.25

1

24

2.4

17

Brush

Screw

M6x1.0

2

8

0.8

5.8

Timing plate

Screw

M6x1.0

1

8

0.8

5.8

Starter motor

Bolt

M6x1.0

2

7

0.7

5.1

Oil level switch

Bolt

M6x1.0

2

7

0.7

5.1

Drive shaft

U Nut

M14x1.5

1

110

11.0

80

Bearing cap

Bolt Nut

M10x1.25 M8x1.25

2

6

23 23

2.3 2.3

17

17

Oil mount screw

Plug

M14x1.5

1

23

2.3

17

Oil drain screw

Plug

M14x1.5

1

23

2.3

17

Bearing retainer

—

M65x1.5

1

110

11.0

80

Final gear case

Stud bolt Stud bolt

M10x1.25 M8x1.25

4

6

17 9

1.7

0.9

12 6.5