Hints and Tips - Identifying JAP Engines
| Side Valve (SV) |
|||
| V | 175 cc. 60 x 62 mm | U | 600 cc. 85,7 x 104 mm. |
| Z | 175 cc. 55 x 73 mm | GT | 680 cc. v-twin 50° 70 x 88 mm. |
| N | 200 cc. 55 x 83 mm | MT | 750 cc. v-twin 50° 70 x 97 mm. |
| B | 250 cc. 64,5 x 76 mm | KT | 980 cc. v-twin 50° 85,7 x 85 mm. |
| A | 300 cc. 70 x 78 mm | KTCY | 980 cc.(8/30) v-twin 50° 85,7 x 85 mm. |
| I | 350 cc. 70 x 90 mm | LT | 1100 cc. v-twin 60° 85,7 x 95 mm. |
| K(Y) | 500 cc. 85,7 x 85 mm | DT | 1323 cc. v-twin 60° 90 x 104 mm. |
| L(Y) | 550 cc. 85,7 x 95 mm | ||
Overhead Valve (OHV) |
HO | 175 cc. 53 x 78 mm | KOC | 500 cc. sports 85,7 x 85 mm. |
| TO | 200 cc. 57 x 78 mm | KOR | 500 cc. racing 85,5 x 85 mm. |
| PO | 250 cc. 62,5 x 80 mm | JOR | 500 cc. racing 80 x 99 mm. |
| POR | 250 cc. racing 62,5 x 88 mm | PTOR | 500 cc. racing v-twin 62,5 x 80 mm. |
| NOR | 250 cc. racing 65,5 x 74 mm | GTO | 680 cc. racing v-twin 70 x 88 mm. |
| BOR | 250 cc. TT racing 64,5 x 76 mm | KTOR | 980 cc. racing v-twin (8/45) 85,7 x 85 mm. |
| SOC | 350 cc. sports 74 x 80 mm | KTO | 980 cc. (8/45) v-twin 62,5 x 80 mm. |
| SOR | 350 cc. racing 70 x 80 mm | JTOR | 998 cc. racing v-twin (8/50) 80 x 99 mm. |
| IOR | 350 cc. racing 70 x 90 mm | JTO | 998 cc. touring v-twin 80 x 99 mm. |
| SOS | 350 cc. grass track 74 x 80 mm | JTOS | 998 cc. sprint v-twin (8/80) 80 x 99 mm. |
| JOS | 500 cc. 80 x 99 mm | W/W | 1100 cc. racing v-twin ? x ? mm. |
| YTO | 500 cc. v-twin 60 x 88 mm | ||
| 1920 | 1921 | 1922 | 1923 | 1924 | 1925 | 1926 | 1927 | 1928 | 1929 |
| P | N | E | U | M | A | T | I | C | S |
| 1930 | 1931 | 1932 | 1933 | 1934 | 1935 | 1936 | 1937 | 1938 | 1939 |
| W | H | Y | Z | D | R | V | F | O | G |
As an example: An engine with the letters KY/C on the crankcase is a 500cc side valve built in 1928