not running right

[blaster82]

i took my top end off today because it will not tun right and i saw that the back of the piston is really scratched up and on the right rear of the piston it is very sharp at the bottom. what could this be from. is also has exhaust fumes comming out from behind the magneto, how is this possible and how can i fix it. will i have to take the bottom end apart.

 

[blaster82]

from another post i think it might be piston slap, if this is what it is will i have to get it bored again or not

 

[dirtyblaster]

if your walls are scrached u will need a hone or bore,if you have fumes coming out of the magneto u probably blew the gasket like piece.i remeber u had very low compression, it probably just wore down over time