Bike shutting off when hot

[Triumph2009]

I recently got a 65 CA77 running again, but it has stranded me every time I take it out. After a few miles it will just die. When I lay my spark tester on the spark plug wire there is no spark. After it cools down, it will restart. I have replaced the coil. What else should i check? Thanks, Jeff

[brewsky]

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