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The Polini Evolution P.R.E. 4 – 70cc Cylinder...
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The Polini Evolution P.R.E. 4 – 70cc Cylinder Kit is an extreme racing cylinder kit designed for Piaggio 2-stroke engines.
This cylinder is designed for:
- High RPM
- Maximum power
- Track/drag/running use
P.R.E. 4 technology is based on an ultra-aggressive transfer port design, a very high port timing, and tight tolerances, resulting in a complete and consistent engine configuration.
Specifications:
Bore (mm): 47.6
Stroke (mm): 39.3
Displacement (cc): 69.9
Piston pin (mm): 13
Squish (mm): 0.45
Connecting rod length (mm): 90
Ring ring tolerance (mm): 0.2-0.25
Piston-to-cylinder clearance (mm): 0.05-0.06
Compression ratio: 16.5
Tightening torque - cylinder M7 (Nm): 14
Tightening torque - cylinder head M7 (Nm): 14
Tightening torque - cylinder head M5 (Nm): 8
Kart track fuel mixture percentage: 3.50%
Race track fuel mixture percentage: 4%
Optimal operating temperature (°C): 50-55
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