Slot-controlled, fan-cooled 41 mm (55 ccm) tuning cylinder compatible with Swiss Sachs 50/2 and 502 engines, which were installed in Alpa, Caravelle, Comet, DKW, Eiger, Göricke, Hercules, Prior, Pony Junior, Rico, Rixe, and Walco mopeds.
Chrigi from Gfellers-Zweirad was personally involved in the development of the “Wummer” racing cylinder and tested it extensively. His feedback was directly incorporated into the design. The result is a cylinder that delivers impressive performance, especially in the mid-range. The focus here is not on peak power, but on smooth, strong power delivery.
The M40x1.5 mm exhaust thread allows for the installation of all standard exhaust systems. Thanks to the stock-style 37x37 mm bolt pattern for the cylinder head, all standard heads can also be mounted here.
The cylinder is camouflaged with the “30 km” lettering.
Notes:
The cylinder is shipped loose and without a piston, gasket set, studs, or other mounting parts.
The 60x40 mm bolt pattern for the cylinder studs is designed for Swiss engines and is therefore not suitable for German models.
For optimal power output and a precise fit, the cylinder should be used with a 17 mm swiing® tuning carburetor. This should be installed with a short air filter cap, a matching clamp (short), and the appropriate cover plate (long/deep).
You can find all the optional products listed here in the accessories section.
A good, affordable standard replacement part. GPO – GOOD PARTS ONLY.
| Manufacturer | GPO |
| Material | Gray cast iron |
| Displacement | 55 ccm |
| Crankshaft stroke | 42 mm |
| Nominal diameter | 41 mm |
| Ø cylinder neck | 44.8 mm |
| Hole spacing inlet | 32 mm |
| Ø Outlet outside | 40 mm |
| Camouflaged | Yes |
| Number of fixing points | 4 pcs |
| Outlet type | Union nut |
| Sachs | 502 (Saxonette) - AL , AML 50/2 - L CH (0.8 PS) , ML CH (0.8 PS) , MB (2.6 PS) , MLB (2.6 PS) |
Accessories & related products
GPO piston 40.96 mm | Sachs 502, 50/2, 50/3, 50/4
Manufacturer: GPO · Nominal diameter: 41 mm · Ø outside piston (A): 40.96 mm · Compression height (C): 28 mm · Curvature (D): 2.5 mm · Total piston height (E): 52 mm · Number of piston rings (F): 2 pcs · Piston ring mold: Rectangular ring · Piston ring impact: Internal fuse (IS) · Ø piston pin (B): 12 mm · Piston ring height: 1.5 mm · Weight piston kit: 90 g
39,90 EUR
Gasket cylinder base 0.5 mm | Sachs 50/2, 503
Place of use: Cylinder base · Material: Sealing carton · Thickness: 0.5 mm · Hole pattern [mm]: 60 x 40 · Area of application: Standard · Alternative version of the Pony OEM number: A1848 · Alternative version of the Sachs OEM number: 0250 113 100
4,60 EUR
swiing® revival carburetor 17 mm Bing SSB 1/17/69
Manufacturer: swiing® revival parts · Material: Aluminum · Component group Carburetor: Carburetor complete · Nominal diameter: 17 mm · Carburetor type: SSB · Hole spacing inlet: 31 mm · Mounting type: Flange · Camouflaged: No · Nozzle size: 76 · Total length: 132 mm · Ø fuel hose connection: 6 mm · Mixed oil connection: No · Width: 85 mm · Vacuum connection: No · Height: 100 mm · Choke control: without choke · Area of application: Standard · Area of application: Tuning
149,30 EUR
swiing® revival stud bolt set M5x26 inlet (10.9 strength) | Sachs 50/2, 502, 50/3
Thread type: M5x0.8 (standard thread) · Manufacturer: swiing® revival parts · Material: Steel · Surface: galvanized (blue) · Drive: External hexagon · Nominal diameter (thread): 5 mm · Total length: 26 mm · Thread length: 7 mm · Width across flats: 8 mm · Thread length: 14 mm · Strength class: 8 · Strength class: 10.9
6,70 EUR
swiing® ingenious 41 mm cylinder head tuning | Sachs 50/2, 50/3, 50/4
Manufacturer: swiing® ingenious parts · Material: Aluminum · Surface: sandblasted · Ø cylinder: 41 mm · Number of fixing points: 4 pcs · Ø outside: 98 mm · Ø screw holder: 19 mm · Hole pattern [mm]: 37 x 37 · Total length: 127 mm · Candle thread: long · Decompressor: M10x1.5 · Width: 95 mm · Height: 50 mm · Area of application: Standard
80,60 EUR
NC-Motorparts 41 mm Cylinder Head Tuning | Sachs 50/3, 50/4 LKH
Manufacturer: NCMotorparts · Material: Aluminum · Surface: sandblasted · Ø cylinder: 41 mm · Camouflaged: Yes · Number of fixing points: 4 pcs · Ø outside: 128 mm · Hole pattern [mm]: 37 x 37 · Candle thread: long · Decompressor: No · Area of application: Tuning
114,00 EUR
BAD ASS cylinder head L Ø 41-43 mm | Sachs 502, 50/2, 50/3, 50/4
Manufacturer: BAD ASS · Material: Aluminum · Ø cylinder: 41 - 43 mm · Number of fixing points: 1 pcs · Number of fixing points: 4 pcs · Ø outside: 108 mm · Ø screw holder: 19.3 mm · Hole pattern [mm]: 37 x 37 · Decompressor: M10x1.5 · Area of application: Tuning
176,40 EUR
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GPO piston 40.96 mm | Sachs 502, 50/2, 50/3, 50/4
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swiing® revival sealing rubber fan cover black | Sachs 50/2, 50/3, 50/4 (A1938)
Manufacturer: swiing® revival parts · Material: Polyvinyl chloride (PVC-U_hard) · Color: black · Ø Bundle: 20.5 mm · Ø mounting hole: 17 mm · Ø outside: 22.1 mm · Total length: 7.9 mm · Ø inside: 16.95 mm · Waistband height: 2 mm · Material thickness: 7.8 mm · Pony OEM number: A1938 · Sachs OEM no.: 0260 044 000
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Gasket cylinder base 0.5 mm | Sachs 50/2, 503
Place of use: Cylinder base · Material: Sealing carton · Thickness: 0.5 mm · Hole pattern [mm]: 60 x 40 · Area of application: Standard · Alternative version of the Pony OEM number: A1848 · Alternative version of the Sachs OEM number: 0250 113 100
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swiing® revival carburetor 17 mm Bing SSB 1/17/69
Manufacturer: swiing® revival parts · Material: Aluminum · Component group Carburetor: Carburetor complete · Nominal diameter: 17 mm · Carburetor type: SSB · Hole spacing inlet: 31 mm · Mounting type: Flange · Camouflaged: No · Nozzle size: 76 · Total length: 132 mm · Ø fuel hose connection: 6 mm · Mixed oil connection: No · Width: 85 mm · Vacuum connection: No · Height: 100 mm · Choke control: without choke · Area of application: Standard · Area of application: Tuning
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swiing® revival stud bolt set M5x26 inlet (10.9 strength) | Sachs 50/2, 502, 50/3
Thread type: M5x0.8 (standard thread) · Manufacturer: swiing® revival parts · Material: Steel · Surface: galvanized (blue) · Drive: External hexagon · Nominal diameter (thread): 5 mm · Total length: 26 mm · Thread length: 7 mm · Width across flats: 8 mm · Thread length: 14 mm · Strength class: 8 · Strength class: 10.9
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swiing® ingenious 41 mm cylinder head tuning | Sachs 50/2, 50/3, 50/4
Manufacturer: swiing® ingenious parts · Material: Aluminum · Surface: sandblasted · Ø cylinder: 41 mm · Number of fixing points: 4 pcs · Ø outside: 98 mm · Ø screw holder: 19 mm · Hole pattern [mm]: 37 x 37 · Total length: 127 mm · Candle thread: long · Decompressor: M10x1.5 · Width: 95 mm · Height: 50 mm · Area of application: Standard
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GPO 41 mm "Wummer" Cylinder Kit (slot-controlled) | Sachs 502, 50/2 (CH)
Nominal diameter: 41 mm · Manufacturer: GPO · Material: Gray cast iron · Displacement: 55 ccm · Crankshaft stroke: 42 mm · Ø cylinder neck: 44.8 mm · Ø Outlet outside: 40 mm · Ø outlet inside: 30 mm · Inlet window: 18 x 15 mm · Thread inlet: M5x0.8 (standard thread) · Hole spacing inlet: 32 mm · Ø piston pin (B): 12 mm · Outlet type: Union nut · Number of fixing points: 4 pcs · Hole pattern [mm]: 60 x 40 · Decompressor: No · Camouflaged: Yes
188,20 EUR
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