I pulled my trusty 1955 B33 out of winter storage today and it fired right up, as always. Strangely though, after a couple of hours of sitting, I tried to start it and the kick lever went down without turning the engine. My first thought was that the cotter pin had sheared off, but that wasn't the case. It felt as if the clutch was slipping.
I coasted it down a hill and let the clutch out in second gear which also failed to turn the engine. After a couple of tries, though the push starting did work and I rode the bike for 45 minutes or so without issue. It also started normally after that ride, as if there had never been a problem.
I could understand it doing this if the clutch was shot, but it would just keep doing it, not get better. Any idea what's going on?