39.0 mm Vertex piston with a 1.5 mm rectangular piston ring with internal circlip (IS). The piston set is suitable for the 39 mm swiing original and tuning cylinder kit for Zündapp Belmondo mopeds, Zündapp Bergsteiger M25/M50 mopeds, as well as Alpa Spezial 3000 and Alpa Black River small motorcycles, which have a Zündapp type 247 engine installed.
The piston is more durable and provides minimal additional power compared to an original piston from Meteor. The Vertex piston is characterized by its high-quality and precise fit.
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.
| Manufacturer | swiing® ingenious parts |
| Nominal diameter | 39 mm |
| Ø outside piston (A) | 38.95 mm |
| Ø piston pin (B) | 12 mm |
| Compression height (C) | 26.3 mm |
| Curvature (D) | 1.5 mm |
| Total piston height (E) | 51.5 mm |
| Number of piston rings (F) | 1 pcs |
| Piston ring mold | Rectangular ring |
| Piston ring impact | Oblique push |
| Piston ring height | 1.5 mm |
| Weight piston kit | 82 g |
| Zündapp | Belmondo (Type 247-71) Moped 25 (M 25) / Moped M 50 Bergsteiger (Type 247-434) |
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