Hunting tickover

I have just recently finished building a 420 Auto into a CR frame, the bike goes well and handles a treat despite having a very nondescript pair of rear shocks, The only problem is the engine hunts at tickover which means I have the t/o set a little fast , not good for selecting gear on an auto! Has anybody any idea why, it is a new carb body with 45 pilot jet though I am trying a 55 at the moment, no.2 throttle slide. Do not think it is an air leak as the engine does not speed up and stops easily, somebody suggested the reeds but couldn't tell me why. Any pointers to sort this out would be gratefully received, a slow reliable t/o is a must on an Auto.

I can not help you with the T/O but regarding the reeds I would check them over first to verify they are installed correctly(I have heard it is not so obvious) and general condition(no chipping, wear, etc...). I used to have a 1978 Auto about 30 years ago and the blessing was after replacing 2nd gear I never had to do anything else for it other than change the ATF. I loved it except when the brakes got wet and as you know they love to freewheel down hills. My love of that Auto has me building the 6 speed 1978 390WR I always wanted.