Those are Mikuni (OEM) COPY carbs. At least use actual Mikuni jets...you should be around 280-300, not knowing your elevation.
I looked and Mikuni nor Keihin list a 156, so who knows what you jammed in there.
I unloaded after dark at the dunes one night, sped off right out the trailer not knowing that the vent hose was pinched tight. When the group and I finally stopped on top of a distant dune, I looked down and thought my gas tank was gone. Pulled out a light and it had actually sucked in on itself down inside the side covers to where I couldn't see it. Moral of the story...that engine will one way or another suck in all the fuel it needs. I'd imagine had I went much further it would have eventually starved for fuel though.
Does the choke not help? How cold is cold? Even though FMF recommends 30 pilots, it seems few people use that big of a pilot. Make sure you have the correct bowl in the left carb, indicated by the "BB"
I only use a laptop too. I use a FB album that only I can see to hold my Banshee related pics. Just "copy image location" their and paste here.
Fairly simple.
I'm anal enough to always install a new one. With the off/on torque of the engine, I'd think the probability of that nut coming loose would be greater than I'd care to risk.
Tire choice, gear ratio, rider weight, rider ability, sand moisture content. Tons of things...My Banshee acts different daily in the sand due to moisture (air and sand).
Rocky Mountain ATV has 7 of them. Just spend another $62.92 on oil, packing, plugs, spare clutch cable gasket and other essentials, and shipping is free.