Welcome to our happy little playground.
The search feature on this forum is a very handy tool. Use it wisely, and use it a lot.
Barn finds can be fun, and frustrating, and potentially expensive. One question you have to ask is: Why was it sitting in a barn for so long? Did it die and someone thought they'd get to it later? Did they just get tired of it? Did they crash it in a horrible mixture of speed, wet pavement, and bad riding skills?
Yes, I'm kidding on that last one. Step one would be to get some light on the bike, and see what it looks like. Hose it down, trying to keep water and dirt out of the expensive parts like electrical, carbs, etc. Check the frame thoroughly to see where the rust is, and if it's a good candidate for continuing.
Is everything there: carbs, airbox, electrics, seat, brakes, etc?
Once you decide what to do with it, check back, and we'll walk you through how to check the health of the various systems. We'll help if we can, right folx?
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.