Runs with choke

[Knots]

I have a B/S 12.5 hp vertical engine on a splitter. Model 219802, type 0117E1, code 05102ZA.
After head gasket replacement, engine runs fine but only if choke is about 1/3 on.
Opening choke on warm engine causes the engine to make a popping noise. Popping is random (it does not pop every time the engine fires) and happens every few seconds. I am thinking that it is running lean and maybe main jet is partially clogged. Any guidance would be appreciated.
Thanks,
Knots

 

[Scrubcadet10]

did you reset the valve clearance after you put the headgasket on?

 

[StarTech]

Also can be a bad or missing intake manifold gasket.

 

[Knots]

did you reset the valve clearance after you put the headgasket on?

Yes. Also rechecked valve lash after running engine.
Thanks for your reply.
Knots