gas engines need 3 things to run(for proper combustion)
3: ignition spark
even if you have all 3 factors, one might be off, like too much gas, or wrong timing.
if you are sure timing is good and the woodriff key is good, then it has to be a carb problem. i thing the engine is flooding out.
when you pull the hot start, it acually leans out the engine.(it allows a little more air into the throttle body)
when you pull the choke, it allows more fuel into the throttle body, causing a rich condition.
if you have an air compressor, remove the rear boot from the carb to the airbox(the rubber ducting) and spray air into the carb when you kick it over. i bet from adding all the air to the over rich condition, the bike will start. even removing the airbox might get it to start by adding a lot of air.
what are the jets you have in the carb now?