Yes, it sounds like a new bike is more for you, some people don't have what it takes for an old bike.
Leo
Leo, unfortunately, you're right, some people don't have the patience or ambition for fixing bikes (I certainly mean no disrespect to the individual in question). Seriously though, is there a simpler old bike to work on? I doubt it...
Assuming the problem is only carbs (very very likey) ... maybe timing too? the bike could be fixed by someone with no experience, minimal tools, and consultation on this forum and from youtube in less than 2hrs, 3 tops. Almost certainly without having to buy any parts. Of course cleaning the blue off would help with verification of a job well done by seeing if the pipes blue up again (I think there are products for cleaning blue off - I never had to deal with it so I'm not sure). Nonetheless, I hope this fella doesn't give up - XS400 is a great bike and there's a wealth of support here and elsewhere online for taking care of them.
Cheers ... and don't give up, learning how to fix your own ride (bike, car, airplane, submarine, whatever) is an invaluable skill to develop, if something goes haywire down the road, you'll be equipped to handle it instead of paying a shop $100/hr to do it for you.
- J