..have a mate who is rebuilding a 40hp and has new barrels pistons etc which appear to be correct but the bottom skirts of the pistons are wider than original and are bottoming on the internal case ...if you know what i mean!!! ...anyone had this experience ..i lent him a Cramer and the idiots guide but thats as far as my engine rebuilding experience goes ..lucky enough to have Brother Brian to build my engines ..he mentioned 1200 oversized kits that might need modifying but the kit is clearly marked standard 1200

so the pistons are wrong??

skirts too long??

I can't think of anything You could do
I'm sure he doesn't want to grind them...

Maybe someone else can help

maybe someone guessed they would fit a beetle engine??
whoever made them etc??

LEE

the kit(pistons rings assembled in barrels)came from a reputable VW reseller who is not being very helpful ..this is the second set as the first was missing a gudgeon pin...typical too and frooing over freight cr card debits for two kits etc

Are the conrods the right length? I know its a silly thing to ask, but it almost sounds like they are too short for the crank. I don't know. I hope it all gets sorted though!

A missing gudgeon pin would be a royal PITA, to be sure.

Are they 1300 pistons? Same bore but are the 1300 pistons longer than te 1200 ones? Never had any to compare but someone in the group must have this info.

DH

1300 have same bore size (77mm) but larger 22mm pin. ( 40hp(1200) has 20mm.)

If the kit has 83 mm big bore pistons you may have to lightly clearance the pistons on the underside.
But I have never seen this myself with 1200.

Having to clearance the piston is not surprising with non genuine parts,
but is a pain, being that there is nothing else easily available.

The procedure is common once you start tinkering with different strokes and rods.

Balance afterwards.
Any paint shop should have scales that are accurate enough. 5g is stock bal tolerance.

Make sure that the part is correct before modification!

....thanks all for the advice