Hi Dave,
Had 3 great flights today.

On the 4th i think i stuffed up.
After refueling i did not turn the engine over by hand to check it.
I just connected the glow and hit it with the starter, it kicked then backfired. Mad rattling bad sounds.

I removed the rocker cover found it full of fuel.
then removed the back plate also full of fuel. Found the con-rod bent bearing in pieces gouges up the side of the crankcase. Crank journal gouged.
Gudgeon pin and piston look OK slight mark on the liner hope it will hone out.

I think were i went wrong i had the refueling line T into the supply line from the tank to the carb.
and i did not check for fuel in the engine

It is mounted inverted.

What are your thoughts Dave

Thanks Lawrie