Polini 72cc BBK -- worth repairing?

[stopsign31]

Bought a parts bike last week and received two Polini 72cc BBK's along with other spare parts. It's obvious that both pistons and cylinder walls have been deeply scratched and will not hold compression. Is it worth machining these? I did not see any oversized Polini pistons at Daywot or anywhere else on e-bay. The pistons they did have for sale were $100 each. Has anybody had these machined and an over-sized piston installed, or is this not worth the trouble

[fastplastic]

show pics of scratchs might be able to do a light hone

[Wheelman-111]

Greetings:

Yes they're worth attempting a repair. Polini porting Magic is hard to duplicate, even if you're skilled at machining.

Call Patrick Day to see if he can get OS pistons from Polini along with correct bore dimension specs and instructions..

If not, it might still be worth trying to modify a cheap Taiwanese 48 or 49mm piston to match the original Polini piston's skirt dimensions.

No I haven't done it, but given the choice between a rebored Polini cylinder and a new complete Taiwanese top end for the same money, I'd rather have a Polini.

Good luck!

[Trafficjamz]

Make sure to measure the distance between the top of the piston and he top of the wrist pin.

The polini pistons are very different from the chineese pistons of similar size.

[maddog]

the problem is most shops don't have a hone/bore machine...

[konaking]

the problem is most shops don't have a hone/bore machine...

Dude your retarded. I've never been to a machine shop that didn't have one of those machines. I don't think I've ever seen a helpfull post from you

[fastplastic]

i hate to do this but here it goes.... madog is probley refering to a scooter shop not a machine shop, having a hone and plus he wasnt * or insulting in anyway so i belive he intesions where good...... this time.....

[Dakine]

the problem is most shops don't have a hone/bore machine...

and you call me a dumb * local. Most shops here can do it. Your just * stupid. Message me again. We meet up.

[maddog]

u-r just a dumb * local....

[stopsign31]

Sorry for the delay on posting pictures. Here are some shots I took today. I actually have 2 of these Polini BBK's which are scratched up. Tell me what you guys think....worth repairing??

Polini Cylinder.jpg (17.25 KiB) Viewed 5421 times

Rings are seized and deeply scratched. Can't find an oversized piston.

Polini piston.jpg (14.86 KiB) Viewed 5421 times

Polini scratches.jpg (15.17 KiB) Viewed 5423 times

[bakaracer]

yeah your going to have to over bore that cylinder if you want to use it again.the only way to know how much to over is by using a caliper that has the 2 pointed ends facing outwards to measure how deep those scratches are.pretty much all machine shops will have one of those.

[bakaracer]

i hate to do this but here it goes.... madog is probley refering to a scooter shop not a machine shop, having a hone and plus he wasnt * or insulting in anyway so i belive he intesions where good...... this time.....

Accually pretty much all the moped shops in hawaii have hones.only a handfull have boring machines. having a honning tool is a must if running a shop that does repairs or builds.