Help needed 1986 interstate GL 1200 starts Warms up turn off go back to start only backfires very loud

[Bozco5.0]

I have a 1986 Honda Goldwing inters

tate I’ve rebuilt the carburetors sank carbs adjusted air fuel changed ignition coil wires and plugs. It starts beautifully runs great, until it warms up and you turn it off after letting it sit for a minute if you try to start it just has a loud backfire. I am very good at remove and replace. Troubleshooting I’m weak need help

 

[zman]

First thing I do is check how the plugs are burning, after it backfires does it go back to running good?

 

[Motörhead]

Fuel seeping past a float needle into a cylinder and out into the exhaust maybe?

 

[Motörhead]

Nice looking paint scheme, gold pinstripes on black reminds me of the JPS Lotus F1 back in the day.

 

[Bozco5.0]

First thing I do is check how the plugs are burning, after it backfires does it go back to running good?

After it cools down it starts up

 

[zman]

I would let it sit after a run for maybe 10 min. and pull the plugs, if you have a camera all the better, have a look inside the chamber and see if there is wetness, smell the plug for fuel smell, I am not sure if 1200 has a wasted spark ignition but my gut is telling me you have a cylinder flooding after shut down, heat can cause ethanol laced fuel to purge under heat, it has about a 170 degree boiling point and if a cylinder is flooding during a wasted spark an exhaust valve is open causing a backfire.

 

[DaveO430]

It's probably the pulse generators.

 

[Motörhead]

I knew a guy that put a Mazda rotary into a Triumph Spitfire. Overfueling caused a backfire that blew apart the muffler and lifted the car off the ground. It was loud enough for the police and fire department to be dispatched for a terrorism attack lol