Repairs 2113 Hydro Drive won't start after cleaning carb, new head gasket, valves adjusted

Hello. Any help would be appreciated. I have a 2000 2113 Harmony Hydro drive. It started to smoke from the exhaust really badly and eventually wouldn't run (I thought) because the head gasket was blown and would foul the plug. I replaced the head gasket, took apart and cleaned the carb (twice) checked all the wiring/safety switched for continuity. Starter engages and turns flywheel. I adjusted the valves and the engine is not seized b/c the valves operate and I could see the piston move when I had the cylinder head off. I thought maybe it was timing and pulled the flywheel off and the key wasn't sheared off. Drained the gas tank and cleaned the inline filter. Gas flows freely via the gravity fed line (and yes I have the gas switch to "on" position). Even though the diode was sparking when grounded to the head I put in a new spark plug - and ensured it was gapped properly.

So, I don't think it's electrical because I'm getting a spark. That leaves air and gas as the potential problems? cleaned all jets in carb, new gaskets, etc. Head gasket should stop plug fouling. Valves seem to be working and have been adjusted. Any ideas?