Our Honda 2.3hp came with a very comprehensive manual that includes a detailed section on maintenance. I follow that once a year when putting the outboard away. Dealer servicing at £90(I think) would buy me a new motor every 5 years so is not cost effective. Admittedly we probably do only 10-20 hours/year so it has very light use. I’m not sure that a training session on servicing outboards would add much to the manual, even if you could get a mechanic to run such a course, and presumably each make and model is different. Perhaps obtaining a manufacturer’s manual is the first step. As they say if all else fails read the instructions! 😳
Nick
W9922