Bigger bore ?

Hi !

Have anyone tried to bore the Polini cylinder to fit the
2nd size (63,8mm) piston ?
If my calculation is correct that will take
the Polini kit from 177cc to approx 182cc.
Does anyone have any experience on this ?



if you have to do it because you’ve seized ok, you don’t have other choices except buying a new kit.
If you are considering to bore it to get more performance the increase is so slight that there are much better way to spend money in search of something more.
The first of this way is free: getting an almost perfect set up. Carb, timing…
then get a better exhaust with a caracter to suit what you are after.
Then a light flywheel: PK or the HP (with the need of changing the plastic fins whenever needed) Both of course modified for PX.
A better carb.
And then you have the option for reed intake, even though with the Polini 177 the increase using this intake is much less then if you do it in a Malossi 166.
At the end if you want more you have the option to go longstroke and alter the barrel ports.

To be honest my math’s are rubbish,I’ll take your word for that.

As Curare say’s,it’ll give you no noticable improvement in performance anyway.His suggestion’s are spot on too.

Only time to bore it out is when the piston or bore is shagged.[;)]