I guess it's a toss up as to if not working on an old bike is smart or not. On one hand there are plenty of old bikes still around and people still want to ride them. On the other, if you force these old bikes out of existance by refusing to service them and nipping the home mechanics in the bud by skyrocketing the prices of vintage parts (as Honda did in the 80's), you force the new stuff to move. The local mega Honda bike dealer used to say they'd only work on an old bike if it was "Really clean" (Read= freshly restored), but now they say they won't work on anything older than 1985, unless it's a Goldwing then back to 1980. The Honda shop close to me will work on them during the winter (so they claim). The shop manager is the only one who knows how to do the older stuff, since it looked like all the other shop rats were younger than my bike! But, they are great about hunting up older parts and they've surprised me a few times by actually having some oddball older stuff in stock!
(This was the place that I bought my O-ring chain from. I buy the chain and they send me to the service department so the guy can cut the chain to the proper length and rivet the ends. He takes the chain back, comes out 5 minutes later and says it's all set. I get it home, open the package and find the chain in one long length, with a little packet containing the rivet link and O-rings. Grrr.... So I take it back and ask them to rivet the ends together. I dealt with the manager this time. He calls the guy out and asks him to take care of the chain. The guy replies that I need to bring the bike in before he can do it. It took the manager 10 minutes to get it through his head that the 750's swingarm comes out with one pivot bolt and is a simple U-shape- the chain will loop right over it!!!)
But, sadly the one place around here that will work on old bikes while they have a reputation for doing great work, they make you pay handsomely for it. They must figure, "well, we are the only ones that will work on it, so we can screw you and there's nothing you can do about it!". I called them up about a used caliper for the 360. After 10 minutes of the guy grilling me as to why I needed it, he said I could get a used one for $100.00!! BRAND NEW THEY ARE $92.00!! You can guess what I told him... My uncle also went through a similar story. He called asking for a decent gas tank for is 750. The guy told him he had plenty of nice tanks and they were $150.00 each. He tells the guy he wants a Brier Brown tank, as that's what he has currently. The responds, "Oh... well, I only have one of those and I was hoping to hang on to it.. You can have it for $250.00!" Yeah, right....