hello, i got the original spark plug the NGK BR8HSA. and when its cold out (like morning) it starts and rides fine but it isnt until the atfernoon when it gets warm outside. almost everytime i ride in the afternoon, it starts to sputter and lose power and eventually die. ill wait like 15 mins and it would start up and ride again but would do the same thing again soon after. also, everytime i try to electic start or kick start, it back fires and sounds like its the sparkplug.....help me please? ps i cleaned out the carb, changed the sparkplug twice and still the same results