Polini Cast Iron 70

[hwr]

So last night i picked up a polini cast iron kit with a 46mm bore (68cc?) for $50AUD from a bloke who bought all the stock from a store that liquidated and had been holding onto it for ~2yrs. Needless to say he didnt really know what he had.

So i got the kit home and noticed it had been opened and was missing a piston ring, a base gasket and the o-ring for the head. The box has monza written on it in biro which is essentially a 1e40qmb minarelli clone in Australia. The cylinder is in good condition you can still see the cross hatching and the piston is spotless so i assume its not been used and just opened to find some spares or something.

So i went to the polini catalogue and found the part number 166.0108 for keeways, come CPIs etc. From here i noticed a few things which have thrown me right off;

a) Some kits online appear to have the o-ring head while others have a flat head for use with a copper gasket.

b) Some also appear to have a bridged boost port in the piston while others are a single hole (mine has a single hole)

c) There doesnt appear to be any repetition between different kits available online coming in different combinations


Copper Gasket + Bridged Piston:
www.scooter-center.com/en/product/P1660108/Cylinder+POLINI+70+cc+Sport+CPI+Euro+2+12mm+piston+pin+0+angle+exhaust+flansh?meta=

Bridged Piston + O-ring gasket:

www.scooterdynasty.com/cylinderkit70ccupgradeforminarelli50cc2t-1-1-1.aspx


Polini doesnt even have a clue, check both pictures the real picture has a copper gasket + mystery piston and the exploded view below it has o-ring gasket + mystery piston:
www.polini.com/catalogo/en/risultato.php?op=po&id=133525&categoria=10&modello=557&from=camamo

The box didnt contain any written material however it was made of styrofoam.

Can anyone point me in the right direction in terms of what they think i have?
Also which do you prefer a bridged piston or not? & Copper gasket head or O-ring head?

Cheers

[hwr]

The piston is stamped ASSO-W 2710 Polini

[Jwhood]

Most likely its a polini sports kit,the corsa kits piston has the double window in the piston,some one chime in if I'm wrong!!!

[hwr]

Cheers for the input,
so corsa = slightly higher durations
and contensa = same porting less durations

Perhaps this could be it?
test.sip-scootershop.com/en/products/racing+cylinder+polini+68cc+_p1660105

My piston looks the same and the page mentions a 46mm bore....but they also mention 47mm bore so hard to get a straight answer

[Lucass2T]

Corsa = polini sport with a ported exhaust port. Maybe higher compression. Dunno about any piston and head differences between sport and corsa. But cylinder wise, only exhaust port.

[808ministroke]

Polini corsa has either one usually 2 chrome piston rings the contessa has no chromed rings. The corsa does have a higher and bigger exhaust port lending itself to higher revs. The bridged boost port not so sure only seen a Malossi for a Piaggio have that . Also the corsa for Honda’s have a cutaway at the skirt and at bottom of piston instead of windows . I have a few different corsas and they are all great none of my Minarelli ones had an o ring .on the head just flat copper gasket should be good to go hope this helps.