Stage6 Big Racing 77cc cylinder kit delivers serious performance for Derbi Euro 3 and Euro 4 50cc motorcycles.

Developed in partnership with MXS Racing professionals, this genuine big bore aluminum cylinder — not a simple bored-out standard — features matched transfer ports and an enlarged exhaust port engineered for maximum power. The kit produces 23 hp and 13 Nm on the dyno with standard setup, while optimized port timings (190°–125°), generous cooling volume, and a quality Vertex piston ensure durability.

• Piston pin = 12 mm
• Stroke = Original
• Conrod length = Standard
• Spark plug thread = M14 long

Installation requires no engine block milling and squish clearance is pre-optimized for your engine type.

• Includes 77cc aluminum cylinder with 5 transfer ports and bridged exhaust
• 50mm Vertex piston
• one-piece aluminum high-compression head
• gasket set

Note : Euro 4 models require adapter MF96.91010 for temperature sensor fitment. Not street legal. Please, use with reinforced crankshaft at standard stroke. Long cylinder head nuts recommended for proper assembly.