Gary_in_NJ wrote on 01/13/22 at 11:49:19:A few things here.
First, don't let your engine idle for more than 30-60 seconds before you start to ride.
Second, never let a cold engine idle while on the side stand and limit a warm engine to less than 30 seconds on the side stand. The oil pressure isn't strong enough at idle to properly lube the cams.
Third, other than the idle screw, you shouldn't have to touch anything else on the carb due to cold weather. Once then engine is up to temperature it will work mostly OK in near freezing temperatures. I say mostly because cold air is denser than the air that you have jetted the bike for, and as a result it will naturally run lean (on all circuits). But you don't jet or adjust jetting for a minimal use case.
Lastly, your pilot jet is probably clogged - that's why it wont idle and learches at very small throttle settings. So make good use of the warn weather and pull your carb for a cleaning. I typically don't clean jets, I replace them. However, if you have some old guitar strings, brake cleaner and a good source of compressed air, you can get the pilot jet cleaned.
And a BTW (since I already typed "lastly") a few holes drilled in the exhaust wont require significant jet changes (maybe a number or two on the main) and certainly wont effect the idle circuit.
The bike idles fine after it's warmed up. I start it on full choke, and it idles but dies if I try to give it any throttle, but it idles fast with the choke pulled, and as it warms up I shove the choke in a little at a time, but make sure it has a fast idle the whole time it is warms up. I have rode it a few miles, and adjusted the mix, and get as best idle as I can get( which is a really good even idle, but it still acts lean under light throttle conditions like when you drive in a small town, or side street. It does fine once it gets opened up some. When it acting up, I can reach down with my left hand, and drive with the choke pulled out a knotch, and the engine picks up and runs smoothly. I think I am going to pull the batteries out of my motorcycles , and bring them in till winter is over, so I probably won't be riding for a little while. I just thought I would order a jet kit if that's what I needed, but I guess I should wait till things warm up. Thanks