Hello,
A couple months ago I picked up a '99 CBR600F4 that needed a little work. Wasn't really looking for another bike but the price was good enough that I couldn't pass it up. I just rebuilt the carbs and did a valve adjustment but I'm having an issue with the timing chain when I attempt to reinstall the cams. Everything seems to be in proper alignment. The notch on the crankshaft, the mark on the intake sprocket, and the mark on the exhaust sprocket all line up perfectly. I made sure to leave the only slack in the timing chain between the intake sprocket and the crankshaft sprocket and proceeded to reinstall the tensioner. When I turn the crankshaft manually everything turns easily and all markings stay in alignment after a full rotation. The problem is that at certain points throughout the rotation the chain jumps and seems like it's about to skip teeth on the cam sprockets. It doesn't actually change teeth and everything stays in alignment, but I can't imagine it would be good for this to be happening at 1300rpms. Sorry if I didn't describe the issue very well. I'll try to post a video. Anyone have any ideas how I can correct this?

[YOUTUBE] [/YOUTUBE]

 

Are you sure the cam chain tensioner is applying the correct tension on the chain? I'd think you need some more tension? Is it a manual or stock tensioner? I observed the same thing when I reshimmed my valves last winter but I think it was with the tensioner off the bike.

 

I believe it's the stock automatic tensioner. Could the tensioner just be bad? I feel like it may have been doing the same thing when I turned the crankshaft before I took everything apart. I'm not sure though. I should have payed more attention.

 

I had the same concerns on my F3 recently, although the "jump" would only really be noticeable with the tensioner retracted and chain guard off.

I did some research, and my understanding is that it is simply the valve springs pushing and pulling the cams against the chain slack as they rotate through their cycle.
Mine is running fine after reassembly.

If you still have enough slack for that to happen AFTER releasing the tensioner, I would suggest you might want to take a look at your tensioner.

Good luck!

Edit: your video looks exactly like what I saw on my bike

 

There is a chain guide that goes across the top. Put it on and inspect again.

 

I guess I should probably pick up a new tensioner and see if that solves the problem. I did put the top chain guard on since making that video but the result is still the same.