Head gasket possible, but possibly the bolt where the leak is has a copper gasket or o-ring under it.
Either pretty common on 2-strokes.
Clean & anneal the copper gasket, or replace it, or if o-ring, replace.
Not a bad idea to pull the top end down all the same on any 2nd hand 2-stroke
The torque settings are pretty low on these things 30-40lb from memory.
If you're going to check the gaskets out, buy a set of rings, check out the piston clearance too.
They are cheap things to replace (relative to a 4 stroke) & will make a big difference to the longevity of the motor.
One other thing (from Personal experience)
Replace the reeds annually
These motors are case-reed induction, the reeds can break due to the constant stress from flexing every induction cycle.
Buy some boysen reeds.
When they brake, they don't screw up your motor the same way.
