G'day

I think you need to tell us a bit more about the setup. Is the engine inverted? In a plane? In a test stand? Type of spinner? Prop?

I think you are saying that your starter is having difficulty turning the engine over? If this is the case, the engine may simply be flooded with fuel. If you get lots of fuel in the crank case, as you turn it over, eventually too much will cause a hydraulic lock and the engine won't turn over. You could damage it doing this.

Is the fuel tank mounted too high? The centre line of the fuel tank should line up with the carby centre line. If the tank is higher than this, it can flood the engine easily and cause the hydraulic lock I mentioned.

A true seize occurs when the piston and liner become so hot that they start to melt together or the piston expands so much that it grabs the insides of the liner so much that it can no longer move. All ABC engine "nip" a small amount at the top of their stroke. This is normal and so long as there is oil present it is not a problem. Once the engine becomes hot, this is no longer a problem as the liner expands away from the piston.

Another possible problem with spinners - the prop blades must not touch the spinner at all. It is often necessary to reshape the holes in the spinner to get the blades clear of the spinner. If they are touching, they may distort the spinner and can cause binding or worse, they may eventually weaken the prop blade and one may fly off. If you do reshape a spinner, balance can be disturbed and the spinner should be balanced but that is another subject altogether.

Does any of this help?