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Discussion Starter · #1 ·
Im getting ready to buy piston and ring for my Polini A/c motor . Mid south has 4 different pistons for the 36mm head.Both the A/c and W/C pistons will work they say.
They are all slightly different for squish reason I believe. What one should I get for my cylinder.
Im not looking to make the most HP I can by using tight tolerance and high compression. I can sacrifice compression to gain power in other places. My motor will be going on a scooter that will be driven for long periods of time. So reliability is a must for me. But im not looking for my motor to be a dog.
The bottom of page two and thee will show everything.
Im looking at the stock polini A/c top end and it gives no indication of what piston it uses . I guess I could get the piston with the tightest tolerances and machine it down on the lathe or mill to what ever works bets for my application considering there flat domed pistons.
I dunno Im confused ... :confused:
http://www.midsouthminimoto.com/engineparts.aspx
 

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The code ( Polini =A/B/C/D ) for your needed piston must/ should be compatible with your cyl.; it means look at the bottom sealing area, there you'll find the code nr , the same you need also for your piston;

Polini 36mm pistons have "round head"

available 2 sorts: with stock p-ring or with racing p-ring ( the price diff is by ca. 25 $)

A - 35,955
B - 35,965
C - 35,975
D - 35,985

this has nothing to do with the squish , it's for the compatibility between Cyl & piston
re installing dimension
 

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French Fries N Cheese
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36mm Stihl thin piston rings will do. Or you could opt for the BZM 36mm rings. The stihl ones are 5-8 bucks each depending where you get em. BZM ones are about 15$ + shipping. You could possibly get some Wiseco 36mm rings aswell, but thats only going up in price. I use Stihl 44mm thin rings in my Cags, they work much better than the China crap.
 

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Discussion Starter · #5 ·
What bout pistons? Does BZM make a direct replacement piston to use in a polini cylinder . I was lookig at this one but I figured i wouldnt work .
Does any one know of one at Tsunami that will fit my A/C polini 323 3 port head? I ask cause there other things I wanted from there. Suc to have to order from midsouth and tsunami

http://www.tsunamibike.com/catalog/item/4353127/4576120.htm
 

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What do you want to do generally because you wrote about Polini, then it's BZM... they have different piston types.( but "the same rings ")

Which kind of brand is your cyl.?

BZM for Polini case
or
genuine Polini ( on your polini case )

re rings
simple said ( because normally in front it's a little more info needed ;))

the racing version is extra chromed ( and runs stronger /sharper in your cyl.)
Generally: all performance parts ( when needed) have more wearout , it's normal

re pistons:
Polini piston 36mm = rounded head and other position for the ring-pin
BZM piston 36mm = flat head and different position for the ring-pin vs Polini)

@ Quilette
Polini and/ or BZM rings - are " the same" 36 x 1
so you can use both standard or racing version on it.
( the same as in 40mm version for 50cc)
 

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Discussion Starter · #7 ·
I have series two cases with genuine Polini head that says B at the bottom of it. My cylinder is ok I need new piston and rings.
I sorry im confusing you thats only because im confused.
So the BZM piston will only fit with the bzm head.
I was assuming BZM made a piston to use or replace the stock one when using the polini head.
Heres the PROBLEM im having Midsouth doesnt have my piston (B) in stock. Thats why im looking for another. Can I use the one I linked from ebay?

http://www.ebay.com/itm/170981782541?
ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

http://www.midsouthminimoto.com/143020005-b.aspx
 

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Okay.. against misunderstandings:

when I write
cyl.-head - it's only the head
cylinder - it's only the " bottom "
( because they're 2 parts )

If the Cyl code is "B" then you need also a "B"- Piston ;
( in orig. condtion )
therefor the code stamp ; otherwise it's not the real one you need... look also at the sizes in the post before.

BZM Cyl- Kit for the serie 2 cases is possible but then your Polini Parts are not compatible with this one.

BZM Kit for Polini means only:

BZM Kit to mount on a Polini series 1 or 2 case
( the holes for mounting are different by the cases / distance )

The pistons and heads from BZM are always the same , also for

BZM on Polini case
BZM on BZM case
BZM on Blata case
( + different crank , because the stroke is different - only Blata )

only the cylinder ( bottom) itself is different for mounting / distance between holes .

BZM pistons also have other sizes and codes ( 0-00-A-AA-B-BB )

BZM " B" is not a Polini or Blata " B" in reference of size(s)/ diameter..


Now it's a little more clear ??
 
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