I took an MZ I'd been meaning to ride for 7 years and got it back on the road. Also ran an Enfield bullet for a while.

Why are you wanting to learn this? If you are worried about breaking down in the middle of no where a mechanics course is going to be of limited use. If your drive shaft splines strip you are walking unless you've got a trailer full of what-if bits with you. Regardless of what you read on the internet this is rare, people just don't post in their blogs about days where the bike runs. The days of having to reset timing with fag papers is back in the dark ages.

What you probably need to know is how to tell if bike is in need of a service and possibly how to do some bits of it. Drop the bike in a river and the oil goes brown. You can learn that from the trip reports on here. Brown oil needs changing ASAP. The book that came with the bike tell you how and someone will have put a film of themselves doing it on YouTube. Pick this level rather than having some old boy at night school showing you how to strip a gearbox unless that is what you want to get in to. There are professionals all over the world who'll have the tools and parts to sort the major and rare stuff.

If you want to be free of dealer waiting times, service charges and corner cutting, that is a good reason to try and keep an old hack running for five or ten years. You pick it up as you go along and things break.

Andy