I have the same problem but I like working on my bike and have built others to sell. If he will not read and learn when he gets mad and walks away just pick up the tools and start working or just work on your bike (what made my guy mad was my bike was faster than his because of a little tweeking I did
These engins are tough and will last a long time with basic matanance and making sure the gas and oil is mixed right and tighten the nuts that lossen up befor you go on your ride.
If you are making the bikes make sure to use lock tight (in a pinch I used clear finger nail polish) and the tires are in line that little wobble at 35 is not good.
PS print up the articals you like and make a bike book it will help.
old lady biker