Sudden bogging/stalling after 120 miles - Motomax 250

[CC-John]

The exhaust glowing red would indicate a very lean mixture, or a restricted exhaust. If this bike has a catalytic converter in the exhaust, it could be partially blocked. Try disconnecting the exhaust from the engine and fire it up momentarily to see if it will take throttle. Don't run it for a long period with the pipe disconnected as it's possible to warp the exhaust valve.