1975 Kawasaki KZ400S engine problem Need Help

So, I rebuilt the engine on a 1975 Kawasaki KZ400S and got a re-bore on my pistons to a 1mm over. stock is at 64mm now its 65mm, cleaned the valves but did not move anything, there was no need to.


anyways, put the engine back together, put the engine into the frame....engine is on neutral, so i try to hand crack it, just to rotate it. The crack rotates about a full cycle and maybe a little more, then just stops. i can hear the pistons moving up and down and the compression is all good.


so I have no idea whats preventing it from rotating freely in one or other direction.........


i also noticed that the kick start only goes half way and then stops, it doesn't go all the way down to rotate the crank.


anyone knows what might be going on, let me know.

cam timing off and a valve hitting the piston ? not redoing (at least removing and inspecting) the valves after going to a rebore is not the best plan either.....joe@ vcycle

Agree with Joe. Check valve (cam) timing and keep your fingers crossed that no valves were bent.