'xj600s (1995) cuts out when warm

Hi Roderick:
I'm not familiar with your engine configuration, but on some of the older bikes, vibration eventually can cause a wire to break in the coil. When the engine is cold, the wires make contact and it runs, but as soon as it gets hot, the connection is broken or compromised and the spark quits or drives you crazy.
Since your bike runs when cold and quits when hot, I'd be looking for electrical rather than fuel problems.
Hope this helps.

the idle control motor probly worn-on the throttlbody--also the tps sensor - get intake area inspectd--a haynes manual will xplain complete car-partstore hazit--------starter fluid is used for low compression or weak spark

Check fuel pump relay.
Check fuel pump control cirucuit.
Check fuel pump/

Change the temperature sending unit/temp sensor. When starting, the sensor will tell the computer to put the engine in cold start mode to give a bit more fuel and raise the idle a little so it WILL start and keep running without ever touching the throttle. Once warm-up is completed, this sensor will tell the computer to stop the cold start mode and go to normal run mode. THAT is your only problem.

Change the gasket under the throttle body, you got a chev vacuum leak. common problem

Mostlikely u did something to the computer system when it overheated.If u kept driving it got to hot.

Engine stalls cold or RPM fluctuates at idle up and down or dies near idle.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve but always run a OBD2 fault code as well as the cleaning procedure. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control. If the above cleaning doesn't cure your issues you need to have the computer controlled automatic idle speed control system diagnosed and repaired by a dealer or electronic engine control repair shop.

Sounds like a coolant sensor problem. It signals the ECU for open loop, cold start rich, high idle, until warm up is reached.

check elec

I have a similar problem which seems to stop ,if after 20 mins of driving or warmed up engine if you stop for 10 mins the revs die to a more normal 1500 revs! it is a spanish car now living in theUK I think the problem is choke related.