TOPIC:

I have recently rebuilt the top end of my J with a 1015 Wiseco, new valve seals, valve seat regrind etc.

Whilst the bike runs sweetly when started it is becomming a bitch to start especially when warm.

When cold it starts readily with the choke rod pulled out to the first notch. Once it fires its straight off the choke or else the engine bogs and cuts out. However once warm it will not fire with no choke, but as soon as it fires with the part choke it wants to bog down and stop.

Any ideas? The carb setup is standard jets and settings are unaltered from stock. Standard air box set up with new airbox hoses

not getting enough gas strip down your carbs
either crap in them or huge air leak.

I'm going to say it's an air leak as well.

Once the engine has warmed up, so have the carb manifolds and airbox boots. And all it takes is for one boot/manifold to expand enough to leave a tiny gap or expose a hairline crack in the rubber and there ya go...lean condition!

Have you tried spraying brake or carb cleaner at each individual boot/manifold while the bike is running to see if the idle changhes yet?
If the idle changes, you'll know you've found your problem(s).