trike stalls out

[oldtime3wheeler]

My 83' 70 seems to have a problem. Will start first pull. Idles great, and runs good for about 15 to 20 min. Then it will stall. Wait acouple min. and it starts right bake up but will stall out quickly. Let it fully cool down and it runs for 15 to 20 min. again. Think it could be losing spark when its warmed up. Any suggestions would be great.
Thanks

[Russell 350X]

Does that have a CDI or points? At votec school we converted a CB350 into a trike, and when it got warmed up, the one cylinder would stop firing, could be a similar problem.

[Big red 200es]

Try to remove the gaz tank caps.

[trainingwheeler]

yeah tom check the gas cap does it have the vent u can open or close? if not then it might need new rings . that blue 225 ran like that & shut off like that & thiught it was the cylinder being worn . it actually could be a base or head gasket when stuff heats up & the tolerances grow stuff leaks a little bit . but the ring to cylinder tolerance can do the same