What causes delayed ignition when warm

Very first two steps are to verify that you actually have GOOD ignition when warm.

Check primary ignition voltage and check spark QUALITY

But most of the time, "warm start" problems are fuel related

Fuel boiling/ vapor lock, etc.

Best things I did with mine (before going EFI) was to install a rear mount electric pump, put a heat isolater under the carb, and install a vapor return system using Wix 33040 or-41 filter --5/16 or 3/8 respectively-- which have a built in 1/4" outlet with a return orifice.