I bought a 72 ct2 out of a barn. Cleaned it up. Found it had sheared key in the fly wheel I replace that set timing and points, cleaned carb. and got it running to find crank bearing bad on fly wheel side. So I split the cases and changed bearings and seals. Put it all back together. Now it don't want to run right, first start it would start on choke at very fast idle take choke off and it would go wide open then die like it ran out of gas. So I pulled carb and cleaned again, then it would start run for acouple seconds and die. Ok to my questions Book calls for 230 main jet mine is 200. Pilot jet 25 mine is 25. Needle jet 0-6 mine is 0-6. Needle 4J13 mine is 4L6 and clip in third notch. Do I change the needle and the main jet back to stock?  The bike does have after market exspansion chamber on it.  Any and all help is greatly app.  

Without thinking too hard just yet & considering it was ok but for noisy bearings, i'm wondering about crank seals popped out on one side or other. Or piston in back to front which puts reed inlet holes in the skirt towards the exhaust port & draws air in at tdc. Sorry if no help.--or broken reed petal. Sucked in base gasket. Shouldn't need to go changing jets. Just be sure everything in the carb is 'not blocked' like pilot jet.

Sounds like an air leak.

Not sheared off another key. Need to be done up tight. Wouldn't give lean symptoms but would sure give all sorts of erratic firing & backfiring if it ran at all.

I have checked seals, base gasket, piston arrow to ex., reeds are like new, all new intake gaskets and o-ring. cleaned and blowed out jets and passages twice. checked float height and float.  I'm waiting on new petcock and needle jet o-ring.  will put carb back on and try again.  Can't remember if I moved clip on needle if so, what is the best second from bottom or top. Thanks

Ok, one more poke. Choke jet in the bowl cavity. its a small fixed drilling. If it blocks then openin the choke draws air & no fuel so makes a bad situation worse. Put the needle clip on notch 5--richest. That'll prove a point a least.