Hello everyone -
1986 Suzuki Savage LS650, around 13,000 miles, sitting about 10 years.

Fuel drained, tank off, carb off for cleaning, plug out. I put about 5 to 10 milliliters of 50/50 ATF and acetone in the cylinder and let it soak. On a lift with both wheels off the ground, in fourth gear, I gently turned the rear wheel.
Today, I got more rotation than before and heard a rush of air out of the spark plug hole. But it still stops before a full revolution. I'm not calling it a hard metal stop, but it's a stop and I'm not forcing it.

Also, the crank access plug is seized. I've tried multiple methods and it won't budge. I may have to pull the entire left side cover, but that means lowering the bike off my homemade stand first., drain oil....Not a hateful task, but a step I don't want to take unless necessary.

Thoughts on process and next steps?
Thanks

what z said makes sense, but a little more investigation couldn't hurt as long as you keep to you're doing.

timing port, what tends to happen is someone over tightened it, crushing the oring and getting metal to metal contact. and then it can corrode together. squirt some pen oil or atf on the timing plug, tap it with a hammer to break the bond or least crack it, then make a tool that fits tightly in the slot (I use a front brake pad) a crescent wrench and turn like the devil. I usually twist the plate so don't worry about it... they're free.

look in the exhaust port and see if the valves are bent.