No, don't try to start it again, you've got a problem mate. I presume (but don't know?) that you took the covers off for #3 and 4, and they were opening and closing? If so, yep, you've busted your cam. It's rare, but it's happened here before.
Hopefully you haven't bent any valves, but you'll need to pull the engine out and remove the cam cover to see what's going on in there. Don't get too jaded, it might be as simple as replacing the cam.
I did have an oil starvation issue (silicon sealant) in my K1 in 1981, it ruined the cam, rockers, cam towers, and scored the cylinders so I had to bore it out and fit oversize pistons, but that really wasn't a huge job. Cheers, Terry.