More fun and reliable in what way? Can't say I've ever found the CB550's to have much of a problem in the fuel department unless the carbs are in need of a rebuild, mechanically worn, or just not jetted right. If the bike just doesn't match up to new bikes, then just avoid riding new bikes and pretend that the CB550 is the state of the art and be happy. If you really need more modern carbs, then maybe look at the carbs that were fitted to the 650's, though I'm not sure they would fit or make the bike run well if they did fit.