Won't start when warm

I have a '74 twin 1600. It starts on the first turn every morning and drives like a bomb! Problem is that after the engine warms up, it won't start. The engine is turning fast and I've replaced all of the following: plugs, points, condensor, leads, distributor cap, rotor, fuel filter/hoses, air filter, float needle and seat, float. I can't find anything else to replace else I would!!
Any advise/suggestions would be greatly appreciated!!!

I'll assume you're getting spark, so most likely it's a fuel issue. Is the fuel supply line to the away from the cylinder head tin? I would worry about vapor locking of the fuel line. Has the valve adjustment been checked? Also, the ignition points may not be adjusted correctly & could be closed up when hot. That would cause a no-spark condition when it's hot & won't start.

Choke staying closed is the first thing that comes to mind.

Thanks for the ideas! Funnily enough, the points needed replacing, the fuel line was running close to the intake manifold and was getting very warm and the valves were out of adjustment (too tight). I fixed all of the above but the problem is still there!! (the choke is disenabled and tied open). Another source has said that he thinks it might be the fuel pump. I will replace that today and post again if it solves anything..

O.K. - Solved it. It was the coil... Must have been shorting when it got hot!!!
Thanks for the help,
Happy Beetling,
Brad.