39.0 mm piston with a rectangular piston ring with internal fuse (IS) suitable for Zündapp Belmondo mopeds, Zündapp Bergsteiger M25/M50 mopeds, as well as Alpa Spezial 3000 or Alpa Black River small motorcycles which have a Zündapp type 247 engine installed.
The detailed dimensions 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 | 39 mm |
| Ø outside piston (A) | 38.96 mm |
| Ø piston pin (B) | 12 mm |
| Compression height (C) | 26.3 mm |
| Curvature (D) | 1.3 mm |
| Total piston height (E) | 51.65 mm |
| Number of piston rings (F) | 1 pcs |
| Piston ring mold | Rectangular ring |
| Piston ring impact | Internal fuse (IS) |
| Tolerance group | D |
| Weight piston kit | 84 g |
| Zündapp | Belmondo (Type 247-71) Moped 25 (M 25) / Moped M 50 Bergsteiger (Type 247-434) |
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