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Piston Sizes Help.

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#1 critchie2006

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Posted 17 March 2013 - 01:38 PM

I've just stripped my 1275cc engine to reveal pistons marked 21250 +.060. Can anyone tell what they are and what cc it should be? As much info as possible please. Thanks

#2 ACDodd

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Posted 17 March 2013 - 02:07 PM

These are older piston which is NLA.

nominal 9.4:1 CR and +0.060" means nominally1330cc with a stock crank.

AC

#3 critchie2006

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Posted 19 March 2013 - 05:42 PM


These are older piston which is NLA.

nominal 9.4:1 CR and +0.060" means nominally1330cc with a stock crank.

AC


What would change if it wasn't a stock crank?

#4 mini-luke

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Posted 19 March 2013 - 05:49 PM


These are older piston which is NLA.

nominal 9.4:1 CR and +0.060" means nominally1330cc with a stock crank.

AC


What would change if it wasn't a stock crank?


Depends by what you mean by not being stock, a normal regrind won't change anything

#5 critchie2006

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Posted 19 March 2013 - 06:09 PM




These are older piston which is NLA.

nominal 9.4:1 CR and +0.060" means nominally1330cc with a stock crank.

AC


What would change if it wasn't a stock crank?


Depends by what you mean by not being stock, a normal regrind won't change anything

The crank has been lightened and balanced and the shims have +.020, sorry I'm not that clued up with the technical talk. Joiner so yes I'm probably best sticking to cutting wood :)



#6 Turbo Phil

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Posted 24 March 2013 - 12:33 AM

What AC means is, you will have 1330cc on a standard stroke crank. If the crank is a longer or shorter stroke this will alter the capacity. If the shells are marked +0.020" that just means the crank has been ground 0.020" undersize.

Phil.





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