I solved the Carby heat problem by sanding down the carby a bit and putting a smear of silicon between carby and block. I now have no heat transfer problems.
My only problem now is idling. Top end is great but the dam thing is so bad on idle. Have tested many brand plugs from cold to medium to hot to very hot. Engine runs well on RB P7 - it screams of power - but dies at idle. My OS Tz Spec II is easy to tune, very powerful and idles well. My Hyper 12 just won't Idle. I have change bearings - with no outcome