Going to look at one of these early this afternoon I found on CL for $300. Owner says cylinder 4 cuts out/bogs/misfires under 6K rpm. He cleaned or rebuilt the carb twice, but it didn't fix the problem. Without discounting what he's attempted so far- what else could be the problem besides plugs, wires, or vacuum? Ideally I'd like to fix it and let my brother learn on it for then sell it. If I can't get it running with an extra $100-$150 I'll probably part it out on the ebay.