Was working good for the last couple years, but this year went for a ride, and my front brake shoe came unglued and the bike died. I figured it was the load the stuck shoe was putting on the motor. Got new shoes and went for a ride.. everything fine for the first 5 min (after a good 10 min warn up) then it just dies. Its hard to start back up taking a minute of pulling before it starts, then i can only go a couple hundred feet before it dies over and over. It has fresh gas, cleaned the carb, Checked the vents in the cap, it seems like it will idle all day but when i put a load on it it dies when hot, the last time it died i quickly removed the plug and it had spark. this motor was refreshed by me a few years ago with a hone and new rings, new points, plug, condenser set at .047 btdc, new lifters and intake valve, valves lapped in, could i have a coil flaking out when hot and especially under load???