how much overbore

[3bvert]

this winter, if I have the money, Ill be rebuilding my m42
just how much can these things be safely bored out as I suspect I have one that will have to go a little overbore

except ....yikes.... at pelican parts oversize pistons are 261 each

got to be a better price out there

[e304me]

you can get OEM pistons on ebay for pretty cheap

[gearheadE30]

Buy S52 pistons...

[nando]

you can get OEM pistons on ebay for pretty cheap

made in china pistons, yes, OEM BMW - not a chance.

[dude8383]

86mm is about as far as you want to go.

[2002maniac]

Fwiw metric mechanic goes all the way to 87mm. I wouldn't go past 86 though.

[dude8383]

Fwiw metric mechanic goes all the way to 87mm. I wouldn't go past 86 though.

yeh, i think it gets pretty thin after 86mm.

[nando]

stock S52 is 86.4mm with the same bore spacing as the M20, M42, and M50. I wouldn't sweat it too much.

[3bvert]

the parts house sells them at +50. what bore is that ?
what is an s52 pistion

[Kingb]

the parts house sells them at +50. what bore is that ?
what is an s52 pistion

A piston out of a s52