5 replies to this topic

[critchie2006]

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

[ACDodd]

These are older piston which is NLA.

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

AC

[critchie2006]

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?

[mini-luke]

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

[critchie2006]

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 :)

[Turbo Phil]

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.