pinging noise

i have a fmf power core 2 pipe boyessen reeds. jetting im not sure as i bought it with the mods. the rings i never saw my dad did most of the rebuild the part of teh piston that broke was on the side the top of it wasn't to burnt. it had the pinging noise befor i rebuilt the motor.
 
i have a fmf power core 2 pipe boyessen reeds. jetting im not sure as i bought it with the mods. the rings i never saw my dad did most of the rebuild the part of teh piston that broke was on the side the top of it wasn't to burnt. it had the pinging noise befor i rebuilt the motor.

That pinging noise must have been piston slap!

When Dad did the rebuild was the bottom end split and checked for cracks or holes, cos if a bit of skirt has gone in and punched a hole, the air leak would make it run lean.

It would be a good idea to find out what jets are in there.
 
a piece of piston went through the bottom of the motor but didnt hit anything so we had it welded and i just checked my main jet is 360
 
If you are having ping probs with a #360 main, you must have an air leak.

What were the results of the leak down test, how long did it hold 7psi for?