Description

POLINI 177 cc Racing Cylinder

For Vespa 125 GTR 2°/​TS/​150 Sprint 2°/​V/​Super 2°/​PX125-150/​PE/​Lusso/​Cosa
cast iron, 7 ports
Bore diameter 63mm
stroke 57mm
2 piston ring(s)
with cylinder head

General
performance class: sport
Gudgeon pin diameter: 15 mm
Spark plugs thread type: M14x1,25
thread spark plug: short
heat rating NGK: B9HS
Cylinder displacement: 178 cc
bore: 63 mm
engine type: 2-stroke
type of cooling: air cooled
material: cast iron
material piston cylinder surface: cast iron
cylinder head inclusive: yes
cylinder gasket set inclusive: yes
number of transfers (incl.boost ports): 7
number of boost ports: 3
shape exhaust port: single port (oval)
exhaust mounting: stub
diameter exhaust stub: 37 mm
Crankshafts
stroke: 57 mm
Piston:
number of piston rings: 2
production method piston: cast
Piston rings:
piston ring type: common ring
thickness rings: 2,0mm
Circlips:
circlip type: G-type
wire size of circlip: 1,25mm
Cylinder head:
cylinder head type: one piece
OEM numbers (for comparison purposes only)
Polini 140.0080

Description:
The Polini is the classic racing cylinder for the PX and Sprint 3 channel engines.
A very early high torque makes it an allround cylinder for almost all needs. It is ideal for the so called "plug-in tuning", i.e. simply changing the cylinder without modifying the rest of the engine.

After the conversion everyone is amazed how powerful a Vespa engine can accelerate. The torque turns every steep mountain into a plain.
The only disadvantage is that the Polini doesn't turn very much. At about 7000 rpm the engine runs into a bit of a wall. A longer transmission ratio by means of another clutch pinion is recommendable in any case. Then the Polini easily exceeds the 100km/h mark and the gears can be pulled much longer.

If you are only driving in the city you can use the 24/24SI carburetor of the 200cc models. The carburetor should be driven with a 160 main air jet and a BE3 mixing tube. If the engine still tends to slim down in the upper rpm range a 140-150 main air jet should be fitted.

If you want to go on a big tour with the Polini you should fit a 28-30 mm carburettor for thermal relief. The 177 harmonizes well with exhaust systems that give off their power quite early, such as the BGM BigBox.

In combination with a bgm long-stroke combustion shaft the power output is again increased considerably over the whole speed range. The result is a hefty 187 cc, which provides power in abundance. If you are still not satisfied with this, you can use a file to increase the already quite small forward exhaust angle. The result is a power output which, depending on the exhaust, can easily exceed 15 kW.
For tuning measures which entail an enlargement of the exhaust window and an increase of the working speed, it is recommended to exchange the original piston rings for Grand Sport models. These are much less prone to breakage and can withstand the increased loads well. For further performance increases above the 25hp mark there is also a complete piston with much thinner rings from Grand Sport.

TIP: Please always mount piston rings carefully. Piston rings made of cast material are only conditionally elastic and break relatively quickly.
Some pistons have trapezoidally profiled piston rings (so-called keystone rings), these only fit in one installation position. If the ring does not move freely, please loosen it carefully and reinstall it upside down.
are very helpful tools for working on the cylinder and/or piston:

Model / manufacturer cc Type Engine Year of construction Addition
LML Star 125 2T/ DLX / Via Toscana / Deluxe 125
2T AC

LML Star 150 2T / DLX / Via Toscana / Star / Stella / Belladonna RV 150
2T AC

VESPA 125 GTR 125 VNL2T 2T AC '68-'78 138957 ->
VESPA 125 TS 125 VNL3T 2T AC '75-'78

VESPA 150 Sprint 150 VLB1T 2T AC '65-'74 105200 ->
VESPA 150 Sprint Veloce 150 VLB1T 2T AC '69-'79

VESPA 150 Super 150 VBC1T 2T AC '65-'79 328129 ->
VESPA COSA 1 125 VNR1T 2T AC '88-'91

VESPA COSA 1 150 VLR1T 2T AC '87-'90

VESPA COSA 2 125 VNR2T 2T AC '91-

VESPA COSA 2 150 VLR2T 2T AC '91-

VESPA P125X 125 VNX1T 2T AC '77-'82

VESPA P150 S 150 VBX1T 2T AC '78-'90

VESPA P150X / PX150 E 150 VLX1T 2T AC '78-'85

VESPA PX125 2011/ 30 Jahre 125 ZAPM74100 2T AC '11-

VESPA PX125 CAT 125 ZAPM50100 2T AC '07-

VESPA PX125 E 125 VNX1T 2T AC '81-'83

VESPA PX125 E '98 / Millenium 125 VNX2T 2T AC '98-'05

VESPA PX125 E Lusso/EFL/Arcobaleno / Elestart 125 VNX2T 2T AC '83-'97

VESPA PX150 2011 150 ZAPM74200 2T AC '11-

VESPA PX150 E '98 / Millenium 150 VLX1T 2T AC '98-'05

VESPA PX150 E Lusso/EFL/Arcobaleno / Elestart 150 VLX1T 2T AC '83-'97