Hot start problems are usualy Ignition module, Coil , Condenser, bad
plug wire, spark plug, vapor lock, air leak, or low hot compression or
simply flooding. Vapor lock caused by cheap gas vaporising in the carb
or line . Air getting into a cracked hose, loose bolt or screw, bad
primer , bad carb gasket leaning out the mixture. Most likely Ignition
or flooding. It could be Ignition Module-coil-consenser or simply bad
secondary ignition - Plug wire, Plug, a simple no spark when hot test
will show this.

My last failures were Ignition Module only when hot, second was plug
wire only when hot.

A compression test hot and cold will rule out head, cilinder-ring
issues and let you know true engine life.

A spark test hot will rule out ignition. If spark is not blue hot and
cold it is ignition.

It could be a bad plug, even new.

A wet plug and blue spark and good compression are flooding.

You have alot of simple things to check first, a warped head as your
mechanic said will not allow motor to run cold-no compression. Start
with better Regular gas only and check spark plug condition. Even plugs
are bought new bad, the stockboy or customer may have dropped it . Ive
bought them bad, and Ive dropped them in the store, and I put them back.