Stiff clutch on old bike

Howdy. I need some advice, if you would be so kind. I'll get right to it.I have a an '87 Suzuki GS450L. It hasn't ran in quite a while, and it's been sitting outside. The clutch on it is really hard to pull in, but when you do, it springs back out. This led me to believe that the problem was the cable. I bought a new cable, and went to replace it earlier today. When I took the cover off the engine ( and with the old clutch cable still attached) The clutch was fine to pull in. But when I attach it to the bike again, it gets really stiff again. I don't get it. Any thoughts would be appreciated. via /r/motorcycles https://www.reddit.com/r/motorcycles/comments/c9p4iy/stiff_clutch_on_old_bike/?utm_source=ifttt