As you and your Honda HS928TA are engaged in some severe-duty operation this season, you may encounter a problem known as predetonation, or “spark-knock”. If you consult the owner’s manual, it will advise that you switch to a different brand of gasoline.
Ignore this. Why Mr. Soichiro Honda of all people would offer this as an appropriate course of action is a mystery.
Do switch to a gasoline with a higher octane rating. If this fails to correct the problem, consider bringing the machine to a Honda Authorized Service Center, where they will make appropriate adjustments to the ignition system.
Then, put the thing away. It’s July for chrissake.