Stage6 Sport MK2 70cc Cylinder Kit – Minarelli Vertical 10mm (Yamaha BW’s / Slider / MBK Booster / Stunt)

The Stage6 Sport MK2 is the upgraded version of the legendary MK1 cylinder kit — a benchmark among scooter tuners worldwide. Stage6 completely redesigned the MK2 for even greater power, efficiency, and durability, making it one of the best choices for 50cc scooters with Minarelli vertical engines, such as the Yamaha BW’s / Slider and MBK Booster / Stunt.

Design & Construction

The MK2 features a new 6-transfer port design (previously 5), ensuring optimized cylinder filling and improved performance. The oval exhaust port has been reworked for better gas flow, while the exterior adopts the distinctive pentagonal look of the R/T racing series.
A one-piece cylinder head with integrated scavenging channels enhances heat dissipation. The R/T-style piston, equipped with a domed crown and a 0.8 mm thin piston ring, improves both output and thermal stability.

Performance

This 70cc cylinder delivers approximately 12 hp with the right setup — around 2–3 hp more than the MK1 version. It combines exceptional reliability, strong torque, and high-end power, setting new standards for sport-level tuning cylinders.

Recommended components for best results:

• Reinforced crankshaft

• Minimum 19mm carburetor

• Sport or racing exhaust system

Installation & Setup

• Clean engine thoroughly before installation and inspect all parts.

• Replace the spark plug and small end bearing with new ones.

• Adjust carburetor settings if required.

• Squish clearance: 0.75–0.85 mm

• Break-in period: approx. 300 km with a 1:33 oil mixture

Important:

• Original exhaust systems cannot be used with this cylinder.

• Not homologated for road use in some countries.

Kit Contents:

• Aluminum cylinder (47.6 mm bore)

• Single-ring piston with 10 mm piston pin

• One-piece cylinder head

• Complete gasket set