My bet is crank seal.

Going out to drain the oil and get started. I’ll post what I find. Frankly hoping you’re right. 

 Wet side seal looks to be in place. Interesting someone notched to leading edge of the seal housing...I assume to help lock the seal in place. Doesn’t look like any negative effects from it. Back to to drawing board. At least I know for certain.  Wet side seal looks to be in place. Interesting someone notched to leading edge of the seal housing...I assume to help lock the seal in place. Doesn’t look like any negative effects from it. Back to to drawing board. At least I know for certain. 

Did you say you already popped the head off and carefully look for a crack in the top of the piston?  Won't be a piece missing so won't be obvious.

Well, that ruined that plan--seal in place then. Best left alone until need to change it considering someones efforts to stop it escaping. There's a retainer plate you could add when the time comes if they're available or second hand. Have seen them still bend the plate & get out but must be in an 'explosion in the crankcase' situation.

Haven’t done that yet but that’s next. Trying to clean parts up as I go, changing out grommets and painting fenders. If I can’t get it to run at least it’ll look like I‘m getting somewhere. Mostly surface rust but it’s everywhere. Any idea if the head gasket is reusable...at least temporarily? I’m sure they crush down with the original torque

Just need to heat the head gasket with a propane torch over over a stove. Get it red hot. Can quench it in water, that helps clean it but isn't strictly necessary.

Thanks Darin, I'll give that a shot. Just hoping to assess the condition of the piston and time it correctly while I have it open. Either way I'll be ordering a new gasket once I have the issue resolved. Much appreciate your input.

One thing I noticed when I removed the oil tank to autolube oil line while checking the seal.  The oil smelled terrible...along the line smell of bad gas but worse and it was a color similar to molasses. I’ve drained it and refilled with fresh yamalube low smoke. I doubt it’s responsible for the starting issues but thought best to mention it.