Have a set of carbs from a 1977 xs750 . They may need some work when I got the bike cleaned carbs with solvent as had been sitting for years and wouldn´t run. When put back on bike started on 2 cylinders hit left carb with screwdriver and started to run on all 3. Suspect needle that float pushes up stuck up and wouldn´t let gas in. Unfortunately motor had a bad connecting rod so have a bunch of parts .If you can find out if 77 and 78 are same you can have them for the price of shipping. Put your e-mail address in reply and I will contact you.