First thing that comes to mind is vapor lock or the gas basically boiling out of the fuel rail from engine heat. Try this: go get her on boil, then shut the motor off for a while, then turn it on and off half a dozen times so the fuel pump runs it's prime cycle a bunch of times And see if it starts right up. If it does, you may just need to put a heat shield on your fuel lines. A bad sensor would likely throw a code but it's easy to diagnose the sensors, just need to look up the resistance values and check the sensors with a meter when the bike is hot. As far as your flat spot is concerned I don't think valves are responsible but if they are due, they should be done. It's not a super hard job, but the cams will need to come out if any need adjustment. Not a hard job but definitely labor intensive when you consider that you need to pull off all the plastics to get to the motor.