POLINI BIG VALVE CYLINDER KITS
Cast-Iron Cylinder Kits in 50 cc and 70 cc: The Difference Starts with the Intake.
An oversize reed valve integrated in the cylinder: The Polini project for Minarelli vertical engines for MBK Booster and Yamaha Bw’s is now called BIG VAKVE and is now available in a 50 cc version, with a 40 mm bore, power is not just about displacement.
With BIG VALVE, Polini puts the intake system at the heart of the design: a housing machined into the cylinder accommodates an oversized reed valve compared with the conventional solution.
The technology behind the power
The system features a four-petal reed valve assembly instead of the traditional two-petal design, engineered to increase the flow of the air-fuel mixture. Two dedicated ducts feed the transfer ports directly, a solution designed to enhance torque and throttle response at low engine speeds.
The dedicated flow guide connects the intake manifold to the reed valve assembly, with the aim of reducing turbulence and pressure losses.
An intake system developed to improve engine efficiency and deliver a more responsive feel when the throttle is opened.
Dedicated components included in the kit
The reed valve assembly, flow guide and intake manifold are all included in the kit. Along with the cylinder kit, Polini supplies all the components specifically designed for its intake system.
The 360° adjustable intake manifold allows the position to be selected according to the installation requirements. The system is designed to work with Polini CP carburettors and, where compatible, can be used with either the original air filter or an open filter.
The kit is completed by a racing cylinder head with a copper gasket, a double-ring piston and 0.2 mm and 0.3 mm base gaskets, allowing the squish clearance to be set according to the installation specifications.
The 50 cc and 70 cc versions share the same technical solutions and kit components. The 70 cc version is available with either a 10 mm or 12 mm gudgeon pin, depending on the crankshaft being used.
Item: 166.0118/10 — Cylinder kit, Ø 40 mm
Item: 166.0119/10 — Cylinder kit, Ø 47 mm
Item: 166.0119/12 — Cylinder kit, Ø 47 mm
Retail price: starting from € 234.00 + VAT
100% Made in Italy