Hi, I have rebuilt a CB500 four K1 engine. It was working fine until a crud burst destroyed the main bearings (my fault, a tiny bit of bead shot was left after cleaning it, doh!) Anyway, I rebuild the engine with a new crank and bearings making sure it was spotless this time.
The engine however now seems to stiffen up when the head is bolted down. The crank, primary shaft and gearbox are all turning freely with the head and pistons off. With the head on, I can stand on the kick starter and it won't easily turn over (I'm 12 stone). It turns on the starter.
After running it for a bit, it seized when got warm (I have only run it a very short time). Stripping down the head so far has revealed cam chain scuffs on the head casting (hopefully picture attached).
Any suggestions on the cause (other than me being a plonker)?
