Not sure if its stock pistons or not, I would assume so. I don't think its the battery cause after it cools down it spins over just fine, its only when the engine is hot it turns over really slow.
This is a wrong assumption.
It may even be that the battery is just too small.Or the cables are too small. Or the effective cross section in the battery clamps is too small. I mean you can only suck so much water thru a straw; and so it goes with electrons.
I tend to allow a 9.5 volt minimum cranking volts on a low-perf carbed engine.
67Dart273 gives great advice.
