38.0 mm piston with two 2 mm rectangular piston rings with flank lock (FS) for mopeds, mopeds and small motorcycles with Sachs 502/1 A, 502/1 B, 502/1 AX, 502/1 AX, 502/1 A CH, 502/1 A DK, 502/1 A NL, 502/1 A S and 502/1 A SF engine (colloquially often called torpedo or rocket engine).
The piston set fits the following models, among others:
- Hercules CB1 City Bike, L50, MF1, MF2, MP1
- Rex Miniped, Miniped MK2
- Sparta Happy
- Motograziella
- Pony City
- KTM Hobby 1968 - 1972
The piston pin is closed on one side, as on the original, so that no exhaust gases are forced back through the pin into the intake tract.
The detailed dimensioning of the piston according to the technical drawing can be found in the details. You can also find out about the relevant piston rings, their stems and locking types on the legend in the pictures.
| Nominal diameter | 38 mm |
| Ø outside piston (A) | 37.94 mm |
| Compression height (C) | 28 mm |
| Curvature (D) | 3 mm |
| Total piston height (E) | 53 mm |
| Number of piston rings (F) | 2 pcs |
| Piston ring mold | Rectangular ring |
| Piston ring impact | Flank safety device (FS) |
| Piston ring height | 2 mm |
| Thick piston ring | 1.6 mm |
| Ø piston pin (B) | 12 mm |
| Weight piston kit | 87 g |
| Sachs OEM no. | 0286 373 005 |
| Sachs | 502 1A / 1B (torpedo) |
| Hercules | |
| KTM | |
| Motograziella |
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