Stage6 Streetrace 77cc – Derbi Euro 3 / Euro 4

Stage6 77cc Streetrace cast iron cylinder kit for Derbi Euro 3 and Euro 4 engines. Known for their high-quality scooter CVT parts, Stage6 has expanded into gearbox mopeds and supermoto models, offering powerful displacement upgrades. Following their 50cc line, the 77cc and 88cc kits were introduced under the motto: there is no replacement for displacement.

This 77cc cylinder offers an excellent balance between performance and durability. Acceleration and take-off are significantly improved, and the increased displacement delivers noticeably higher top speed and overall power output. Thanks to its robust cast iron construction, the cylinder is highly reliable and suitable for intensive everyday use. Installation is straightforward and does not require crankcase milling.

Visually, the cylinder remains discreet and closely resembles the stock component. Stage6 intentionally omitted branding on the casting and instead stamped “49ccm” on it. Please note that this is still a 77cc cylinder and may not be street-legal depending on local regulations.

For optimal performance, the overall setup should be adjusted accordingly. Recommended components include a 21 mm PWK carburetor, a Stage6 Viton reed valve, a racing exhaust such as the Stage6 Streetrace low-mount, a reinforced clutch, and a reinforced standard-stroke crankshaft. For high-end setups, an internal rotor ignition like the MVT Digital Direct can further enhance performance.

Running-in recommendation: ride approximately 300 km without full throttle and use a 3% two-stroke mixture (1:33) during the break-in period to ensure long engine life.

Kit contents: 

• 77cc cast iron cylinder, 50 mm bore, 5 transfer ports, single exhaust port
• 2-ring piston, 50 mm
• One-piece high-compression aluminum cylinder head
• Head and base gaskets plus mounting hardware

Important note : Derbi Euro 4 engines use a smaller temperature sensor (M12 x 1.5 thread) compared to Euro 3 models (M14 x 1.5). To install the smaller Euro 4 sensor on the cylinder head, an appropriate adapter is required.