Don't say stupid! Ignorant can be fixed but stupid is forever! Even when ignorant is fixed, retraining is periodically necessary, like keeping mph and kph straight (me!). Many on here have been listening to engines and drive units so long we are nearly deaf but sometimes can still hear things that tell volumes of info. There was a post on here years back that indicated by the sound the rider adjusted his valves with the cam in the wrong position: LOUD CLATTER!