DGrant:
I did pull of the main needle valve seat, removed the needle valve, cleaned both parts with carb cleaner, reassembled, and started the engine, same problemm occurred.
It won't pull fuel to the Carburator. I replaced all the tubings, put clamps on the tubing inside the tank and on all exterior fittings.
I could not remove the Low speed notched disk, it would not come out. I got tired of fighting this issues after a week or so, packed up the engine and sent it off to BJ's Engine Service in CT.
I had another Moki 180, installed it with everything the same. Finally the main needle valve was adjusted to3 turns open, and I adjusted the low speed to 1 click rich, ran great Good transition after the adjustments Tacked the engine at 8500 WOT with a MA 18X8 prop.. I am waiting to see what Bill Jensen finds, I'll bet it's either a bad "O'" ring either in the low speed disk or the hi speed, I checked the hi speed o ring and it looked fine?? Mind you, the origional engine was brand new, the other one I installed was like new, I purchased it on RCU
The guyswho responded to this thread, gave me their opinions, which is great and I thank them, however plugging up one pipe on a Pitts Muff, or installing a Pump or Regulator is not nescessary as you stated, I agree and so did Bill Jensen. These engines run great , once tuned properly,
I used Medium fuel tubing with clamps, 1/8" ID, and these engines will work on 3/32"tubing as well. They do suck fuel, so I opted for the larger size.. That didnot make any difference on the origional problem.

I agreed with you, do not drill anything, and I did not.
If the engines neededa Perry pump or cline reg, they would have stated that, which they do not.You do not need to drill out the clunk to 5/32", it works fine with any clunk. I used the origional one I installed, works fine.