J.A.P.

The range of J.A.P. engines is vast and only the most popular models are listed below. All J.A.P. big ends are available and many more are listed in the bearing configuration tables. These tables are only available to the public upon request from the factory.

80cc

Year

Model

Con rod casting No.

Big end Part No.

Cage Part No

Small end Part No.

MAIN BEARINGS

Drive Side

Timing Side

––

Numerous power tools

––

JAP80

-

-

-

-

250cc

Year

Model

Con rod casting No.

Big end Part No.

Cage Part No

Small end Part No.

MAIN BEARINGS

Drive Side

Timing Side

––

O.H.V. models

––

––

––

––

––

––

1934 PO-Z

7464/1

JAP1/A

K17

SE41

––

––

1934 PO-Z

7464/1

JAP1/A

K17

SE41

––

––

1935-37 PO-Z

7464/2

JAP1/B

K18

SE41

––

––

1936-39 PO-O, PO-F, OK Supreme

7464/4

JAP1/C

K19

SE41

––

––

350cc

Year

Model

Con rod casting No.

Big end Part No.

Cage Part No

Small end Part No.

MAIN BEARINGS

Drive Side

Timing Side

––

O.H.V. models

––

––

––

––

––

––

1937 GH & OK Supreme

9314

JAP2/A

K20

SE41

––

––

All Years Speedway

Alloy

JAP4

K22

SE44

––

––

500cc

Year

Model

Con rod casting No.

Big end Part No.

Cage Part No

Small end Part No.

MAIN BEARINGS

Drive Side

Timing Side

––

O.H.V. models

––

––

––

––

––

––

1932-37 KO-Z

8522

JAP3/A

K20

SE42

––

––

1938-39 KO-Z

S378M

JAP3/A

K20

SE42

––

––

1936 KO-Z

8522/1

JAP3/B

K21

SE42

––

––

All Years Speedway (Alloy Rod)

Alloy

JAP4

K22

SE44

––

––

All Years Speedway (Steel Rod)

Steel

JAP4

K22

w

––

––

 

600cc

Year

Model

Con rod casting No.

Big end Part No.

Cage Part No

Small end Part No.

MAIN BEARINGS

Drive Side

Timing Side

All years Industrial  

JAP3/A

K20

SE42

 

1000 & 1100cc

Year

Model

Con rod casting No.

Big end Part No.

Cage Part No

Small end Part No.

MAIN BEARINGS

Drive Side

Timing Side

1936-40 980cc & 1100cc Twin

––

JAP5

––

1945-61 1100cc Racing Twin

Polished

JAP11

K76

SE188

LS12

RLS12

 

 

The table below shows some of the piston data and perhaps more interestingly gudgeon pin sizes for most of the JAP machines. In keeping with JAP machines there are many choices between similar models.

 

Model Material

Bore

Ref. No.

Height

Length

Head Form

Pin

288cc Model 4/3  

70mm

13105

19/32"

215/32"

Flat

15.58mm

500 Speedway  

80mm

18547/HR

147/64"

37/64"

Radius

13/16"

500 OHV Heplex

33/8"

7160

113/16"

3"

Radius

13/16"

Model 6 588 SV  

33/8"

9860

127/32"

315/32"

Flat – Bevel

13/16"

600 SV Heplex

33/8"

S5891

1"

3"

Flat

13/16"

680 SV Heplex

2"

929

15/8"

227/32"

Flat

15.62mm

680 OHV Alloy

70mm

3409

15/16"

231/64"

Flat

15.62mm

980 SV Alloy

33/8"

S7306

121/32"

33/16"

Flat

13/16"

980 SV Heplex

33/8"

3332

15/8"

3"

Flat

15.62mm

980 SV Sports Heplex

33/8"

1939

15/8"

3"

Flat – Bevel

13/16"

990 SV (Side by Side) Alloy

33/8"

S7963

113/16"

3"

Flat – Bevel

7/8"

990 SV "X" Alloy

33/8"

S7333

113/16"

3"

Flat – Bevel

7/8"

1100 OHV Alloy

33/8"

3395

17/8"

3"

Radius

13/16"

1100 OHV Alloy

33/8"

3331

17/8"

3"

Radius

13/16"

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