Polini BIG EVO racing cylinder Polini 152cc for Vespa Smallframe PV125 / PK125

Big Evo racing cylinder POLINI aluminum 152cc / Evolution reed valve Vespa Smallframe

The new Polini BIG EVO! Here we have introduced you to the classic 133cc Polini racing cylinder. If that's not enough for you, there's now the Polini BIG EVO for the Vespa Smallframe. This modern racing cylinder means a full 152cc for the original standard engine cases of Vespa Smallframe models such as the V50, 50N, PV, ET3, PK etc.. So you don't need an extra engine case!

30hp + tuning set for original engines

With Ø60mm bore and 54mm stroke, as well as very ambitious head angles straight out of the box, the Polini is a serious contender for the racetrack. Based on the very successful Polini EVO 133, Polini has put together a super package that was created for performance above 30 hp!

Polini Big Evo 152 Vespa

Data of the Vespa Polini tuning kit

  • Bore: Ø60mm
  • Stroke: 54mm
  • Displacement: 152cc
  • Crush size: 1±0.1mm
  • Connecting rod length: 105mm
  • Compression ratio: 14.2:1
  • Piston running clearance: 0.07 - 0.08mm
  • Exhaust shape: Two-piece
  • Exhaust angle: 194°
  • Overflow angle: 130°
  • Pre-ignition:
  • 20°
  • Spindle size left crankcase: Ø89.5 x 22.4mm
  • Spindle size right crankcase: Ø89.5 x 15.8mm

INLECTOR

The Polini kit contains the complete intake tract, consisting of: large diaphragm intake, intake manifold and connecting rubber. The 6-valve diaphragm is equipped with 0.4mm thick plate material. The intake manifold is designed for use with a Ø34mm carburetor cross-section (carburetor connection width of the rubber is Ø44-45mm).
Modifications may be necessary in the area of the frame cut-out for the carburettor
.

PISTONS

The Polini tuning set for Vespa uses the well-known Asso piston from the Polini Aprilia AF1 kit, as already used by FALC Racing in its 153cc cylinders (we can highly recommend the very high-quality Ø60mm Wössner piston from Overrev as an alternative).

CURB SHAFT

Any shaft with a 54mm stroke and 105mm connecting rod length can be used as the crankshaft.
The connecting rod length not only benefits the better connecting rod ratio, but also reduces the necessary housing adaptations for the overcurrent channels to a minimum.

SPINDLES

The engine housing must be spindled out accordingly for the necessary crankshaft with 54mm stroke
.

CYLINDER HEAD

The cylinder head is bolted with 4 screws in addition to the conventional bolting, using the continuous (longer, enclosed) cylinder stud bolts.

Recommended accessories/setup:

  • Crankshaft: P2100070 or comparable (54/105mm)
  • Exhaust system: P2000416 or comparable
  • Ignition: P1710554 or comparable
  • Dynamic ignition timing (with P1710554 ignition): 4.8mm before top
  • piston dead center at 4500 rpm
  • Spark plug: NGK BR9EG or comparable

CONCLUSION:

Very interesting alternative for normal engine cases to the often unavailable FALC racing cylinders. If you are looking for power well above 25 hp, you will find it here!

Installation instructions Polini racing cylinder

Polini-BigEvo-152-racing-cylinder-PI776

Fits the following Vespa Smallframe:




Edition:
Autor
Uwe Schneider