Just lurking here but what are referring to as "ID"? Not familiar with that term.
If the plug is hitting the piston then there should be witness marks on the piston and if the timing has been advanced it will normally want to bite back at you and pop back taking the recoil handle from you if you don't have a strong grip but normally they will start without having to pull on them to many times.If it spins fine without the plug in, and there is a problem when the spark plug is in, could the plug be too long and hit the top of the piston? Just a wild shot.
Or maybe too much timing advance?
Check the top of the piston closely again you might need to pop the cylinder and make some room for the plug but never the less make sure it's got the right plug to start with squish is fine at .19 I wouldn't go much tighter than that if it's a work saw someone might have taken the base gasket out or musheind the base of the cylinder if indeed you're squish is .19.MG that's chrome not grey.
Kevin, great tip, no change.
AVB, I never took short hand either,
that was for girls.
It does look like the plug leaves a mark on piston,
maybe that's normal, Plug gap not smashed.
I had multiple starters on it, hate to parts out another saw but could
just to try.
Didn't check key yet, no clean good rope and no impact here.
I guess that's next.
Piston quench seems .019 to .022 according to my HF calipers.
Saw was bought used as 55 CP.
I used single strand .045 solder.
I'll mess around more tomorrow, rain day,
had plenty enough today.
Youns have been great thanks.
Yes and normally the blow off valve pops right when there ready to fire. Let us know what you find out with the flywheel key if someone has messed with it.I thought of the plug depth. New ones from internet are same as the one was in it but that means nothing. I'll go look around.
It has a base gasket, appears old.
Snap bang compression is great I like it too. Not so much when it pops the decomp, while working big blow downs in a swamp, while balanced on the end of,,, lol.