Gear Box

Description

Dimensions

Maximum Wear

Low gear wheel bushes internal diameter

0.625" + 0.0007" -0.0005"

 

Wear - maximum clearance between bush and shaft

- maximum wear on shaft

 

0.006”


0.003”

Lay shaft bush internal diameter

0.8125 +0.0007" -0.0005"

 

Wear- maximum clearance between bush and shaft

- maximum wear on shaft

 

 0.006”


0.003”

Lay shaft end float

0.005 (optimum) – 0.015"

 

Main shaft end float

0.005” (optimum) – 0.010”

 

Selector fork thickness

0.245"

 

Selector fork grove width

0.257”

 

Maximum clearance selector fork to grove

-

0.020”

Measurement between selector fork prongs

1.213”

 

Selector Fork peg diameter

0.270”

 

Selector rod diameter

0.375”

0.004”

K191 Kick Start Thrust Pins

0.5625” X 0.1875”

-

C6/3 Back Plate Clutch Thrust Pins

0.453” X 0.1875”

-

C30 Clutch Operating Thrust Pin Length

1.343” or 1.328”

 

B22/2 & B23 bearing wear

- radial

- axial

  

 

0.004”

0.006”

B22

- radial

- axial

 

 

0.004”

0.005”

Shaft to bearing interference fit

0.001”

 

 Cam Plates

 

 

 

 

 

 

 

 

 

 

 

 

Gear Box Pinions 

Viewed from kick starter to clutch end of gearbox

Prefix 11 and 14

Gear

1st

3rd

  2nd

4th

Gearshaft pinion teeth

26

19

22

16

Layshaft pinion teeth

18

25

22

28

 Prefix 12

Gear

1st

3rd

  2nd

4th

Gearshaft pinion teeth

26

19

22

17

Layshaft pinion teeth

18

25

22

27

 Prefix 12R

Gear

1st

3rd  

2nd

4th

Gearshaft pinion teeth

25

19

22

18

Layshaft pinion teeth

19

25

22

26

 

 Gear Ratios

Gearbox Prefix 11

Sprocket

First Gear

Second Gear

Third Gear

Fourth Gear

MAC

21T

14.1

9.6

7.3

5.5

  

Gearbox Prefix 12

Sprocket

First Gear

Second Gear

Third Gear

Fourth Gear

12 (MSS to 55, VM

18T

11.24

7.78

5.91

4.9

 

20T

10.1

6.97

5.3

4.4

 

19T

10.65

7.36

5.6

4.63

 

17T

11.91

8.23

5.27

5.18

 

16T

12.62

8.73

6.64

5.5

 

Gearbox Prefix 14

Sprocket

First Gear

Second Gear

Third Gear

Fourth Gear

MSS

18T

12.4

8.57

6.52

4.9

 

20T

11.18

7.74

5.98

4.4

 

19T

11.76

8.15

6.30

4.63

 

17T

13.16

9.17

7.05

5.18

 

16T

13.91

9.68

7.32

5.5

  

Gearbox Prefix 12

Sprocket

First Gear

Second Gear

Third Gear

Fourth Gear

Viper

21T

12.62

8.73

6.64

5.5

 

20T

13.25

9.16

6.97

5.76

 

19T

 13.94

9.64

7.33

6.06

 

18T

 14.72

10.18

7.74

6.40

   

Gearbox Prefix 12R

Sprocket

First Gear

Second Gear

Third Gear

Fourth Gear

Venom Clubman

18T

9.25

7.03

5.35

4.9

 

20T

8.36

6.34

4.84

4.4

 

19T

8.80

6.67

5.09

4.63

 

17T

 9.84

9.64

7.33

6.06

 

16T

 10.45

10.18

7.74

6.40

 

Gearbox Prefix 12R

Sprocket

First Gear

Second Gear

Third Gear

Fourth Gear

Viper Clubman

21T

10.45

7.94

6.03

5.5

 

20T

10.94

8.29

6.34

5.76

 

19T

11.54

8.73

6.67

6.06

 

18T

12.16

9.22

7.04

6.40

 

Gearbox Prefix 12

Sprocket

First Gear

Second Gear

Third Gear

Fourth Gear

Thruxton

20T

10.1

6.97

5.3

4.4

 

21T

9.66

6.68

5.08

4.2

 

19T

10.65

7.36

5.6

4.63

 

18T

11.24

7.78

5.91

4.9

 

17T

11.91

8.23

5.27

5.18

  

Gearbox Prefix 12R

Sprocket

First Gear

Second Gear

Third Gear

Fourth Gear

Thruxton

20T

8.4

6.3

4.83

4.4

 

19T

8.80

6.67

5.09

4.63

 

18T

9.25

7.03

5.35

4.9

 

17T

 9.84

9.64

7.33

6.06

 

16T

 10.45

10.18

7.74

6.40

  

Chains and Sprockets 

Model

MAC

Viper

C/man

Viper

MSS

Venom

Venom

C/man

Thruxton

Primary chain pitches

0.5-in. pitch; .305-in. wide; 335-in. roller dia. 

67

67

67

68

68

68

68

Rear chain pitches

.625 –in pitch; .380-in wide; .335-in. roller dia.

 

 

 

101

101

101

101

Rear chain pitches

.5-in. pitch; .305-in. wide;

 

124

124

 

 

 

 

Engine sprocket

 

21

21

23

23

23

23

Clutch chainwheel

44

44

44

44

44

44

44

Gearbox Std.

 

21

21

18

18

18

20

Rear wheel

 

55T

55T

46T

46T

46T

46T

Engine Shock absorber spring length, new

1.665"

1.665"

1.665"

1.665"

1.665"

1.665"

1.665"

Engine shock absorber spring, min length

1.56"

1.56"

1.56"

1.56"

1.56"

1.56"

1.56"