I bought a kh 20 about a week ago and Im learning crankflips on it but kicking the pedal as hard as I can I can only just get it to spin twice before it stops. on my old uni which has just had a new hub I can spin the cranks way faster with less or the same amount of effort. has anyone else had the same problem? after a while of riding will it spin easier and faster?
sorry man, mine KH bearings spin fine.
just bumping it up for you 
Probably not but I could be wrong. In my experience new bearings spin better than old ones.
Check your bearing holders, they may be done up too tight which will cause them to do this, if you have overtightened the bearing holders that can also damage the bearings perminantly by “crimping” them slightly. But yeah, just make sure their not too tight first.
That’s what I thought which is why I was surprised when they didn’t, they are significantly worse than on my other uni which also has a new hub 
I will try that thanks, I’m not sure it will make a difference, I think it shouldn’t but I am willing to try it as it will be easy, the only things I could think of is that the seal on the KH Bering’s are better than that of my other cheaper uni so the seals are tighter and produce more friction or that they just need wearing in but as no one else has had the same problem I am not sure, now im just hoping that loosing off the Bering holder will solve it although there not very tight at the moment :S
so how tight does everyone else do the bolts on there bering holders up?
I cant loosen mine of yet because I am in school so I was just woundering how tight everyone else does theres up
just tight them utill there is no grinding noise and makesure they are equal
Check whihc type of seal the two sets of bearings have, they do those bearings with either metal or rubber seals, one may well drag mroe than the other (I guess it would be the rubber seals).
For bearing housings I tighten them with the long end of the wrench in the bolt, so I only have minimal leaverage on the short end. A firm twist with the key set this way should suffice.
thanks for your advice, I used the allen key like you said so they are now alot looser I gave it a quick spin and it now it spins easly and keeps spining for ages, thanks again, bring on the crank flips 