Pull the spark plug and carefully inspect the insulator and electrodes for evidence of lean burning. Here a a reference that may be of help:
Spark plug reading
If the plug is good, the engine runs good, and it is just a matter of a red pipe, that is normal with a properly tuned engine that is run hard. Most people never see the red pipe because they do not run that hard, or have jetted a bit on the rich side so they can subsidize the oil companies.