Bucking osselation & 'Raao' sound in high gear (shift kit)

I have the same issue on my bikes. It turned out both of my heavy duty flywheels were not turning true and were slightly warped. This caused the rear chain to touch the shifter kit chain once a revolution. You may want to see if this is your problem.

Master links can also cause this issue. The solution in that case is to not use a master link.

Nother one ta throw in the mix heh - I had a not dissimilar "pulsing" w/my shiftkit and it 'bout drove me insane trying to track it down, turns out it was simple 'nuff. With the bike on a stand I backpedaled the crank by hand and saw that the crankset & sprocket were moving, there was a a small but perceivable offset. Here's a lil vid of the problem: http://s305.photobucket.com/albums/nn210/Serenity151/vroom/?action=view&current=MVI_1624.mp4 (notice the chain slacking)...

I swapped out the freewheel bearing, tried a different crank, tried a different sprocket, even tried a different cartage... what it turned out to really be is it's almost impossible to get the pedal crank/freewheel bearing/sprocket assembly to be perfectly centered on the square, tapered end of the cartage... odd as it may sound. Removing the pedal cranks & reinstalling them to reseat the press fit massively reduced the "pulsing" effect for me (I did rotate them to the next face, but I dunno if that's did anything)... but it' not quite completely gone... jus' gone e'nuff lol *shrug*

From my experience, the biggest cause of this is the small 12-link jackshaft chain. If it's loose, has a halflink, or master link - or a combination of loose + different link - it can cause those oscillations.

Next up is the 2nd jackshaft chain. The one from jackshaft output to outer sprocket. This is where oscillations first started on my own setup. I put an idler on and the problem went away. I don't recommend running a master- or half-link on this chain, either.

As for the main chain, I get small oscillations at high chainspeeds when I run a master link. Without one, it's just fine.

Barely,
Thanks for sharing the video...that is what mine does exactly but my 'warp/oscillation' is worse with movement than yours. I too replaced all the parts to see if it got better but it didn't. I now live with it and change the spacing on the rear wheel axle so that I have more chain clearance in 7th gear with no chain rubbing under load. I still get the occasional chain rub if I let off the throttle very quickly on rough terrain but its not an issue anymore.

One day a nuvunci will solve this problem