[n4mwd]

The teeth on the crankshaft cam chain sprocket need to be checked. Nothing special, just look to make sure none of them are missing or chipped off.

Bent rods are certainly a possibility. But the only way to check them properly is to split the case and remove the rods from the crank. Then you need to replace the rod bolts which are expensive. I have seen these before, and bent rods, and even bent valves, are not common. The rockers are the weak link and help protect against that sort of thing.

I suggest before you do all that is to remove the cams and chain and plugs and see if that makes it easier to turn. The pistons will make it a little harder to turn, but you should be able to turn the crank easily with a torque wrench on the flywheel nut.

The clutch basket is going to be a lot harder to turn because its gearing it up. That is, you turn the clutch basket once and the crank turns 3 times. Therefore, its not a good place to judge the hand turning torque, because it take 3 times as much torque to turn the crank that way. So don't use the clutch basket to judge engine resistance.