Starting issues

[Bandit1200]

I've just been stranded in town for 3 hours as the Stag refused to start.

The car has been starting with no problems hot or cold, but during the past week after starting from warm, perhaps having left the car for 30mins, the engine seem to run on 4 cyls for about 15 secs then cleared.
This afternoon, I went into town and parked up and returned about 40mins later. The car started, spluttered and died and refused to start. Tried choke but no difference.

Good battery and cranking speed
Checked spark - Good spark at the king lead with still warm engine.
No evidence of tracking on either distributor cap or rotar arm
Checked plugs - Dry and the right colour. New plugs fitted 3000 miles ago.
Checked fuel supply to carbs - Good pressure.
Both pistons free to move in carbs and diaphragms OK. Replaced 2000 miles ago.
No evidence of fuel overflowing or leakage from either carb.
All breather pipes in good condition and connected.

I left the car for 3 hours to cool down after which time it started so I was able to avoid stripping the carbs at the roadside or the indignity of recovery.

I installed new Grose valves 2 months ago and checked float levels.

I'm going to strip the carbs this evening to investigate but would welcome any advice as to the likely cause of the problem.

Thanks in advance.

Steve

[martin]

Hi Steve, with this weather, it sounds like fuel vaporisation, make certain your fuel lines and filter are as far as possible from the exhaust manifold. As you say the plugs were dry, is your inertia switch in good nick ? has the fuel pump become temperamental ? I think most of the stories about vaporisation are attached to witchcraft, my old girl runs on Strombergs, and the under bonnet temp gets as high as anyone else's, but in eight years this has never happened, everything else, but not this Martin.