* The engine is running lean. This means that there is not enough fuel being mixed with the air in the engine, which causes it to run hotter than normal. This can damage the engine and the exhaust system, and it can also cause the exhaust to glow.
* The spark plug is not firing properly. This can also cause the engine to run lean, which can lead to the exhaust glowing.
* The exhaust system is damaged. If the exhaust system is damaged, it can allow hot gases to escape, which can cause the exhaust to glow.
* The jetting is wrong. If the jetting is wrong the air/fuel ratio might not be correct causing it to run hotter.
If you see that the exhaust on your KX450F is glowing, it is important to have it checked by a qualified mechanic as soon as possible to determine the cause and prevent any further damage.
