John, The fuel line tear is a definite indicator of a self leaning problem, You should be able to use medium size line. Also I noticed that you said it was 19 degrees outside. I was playing with one of my nitro trucks sunday and it was like 25 here in NJ. I have found a quick way to tune in very cold weather, Take the HSN very rich until the engine will run very fat at 1/4 to full throttle (Smoking and hesitating) bring engine to full throttle (should be very smoky with alot of oil from exhaust) slowly lean engine 2 clicks at a time until engine speed increases a bit. Move to one click a at time until the engine sounds a little smoother and rpms seem to come up. from there I go to the pinch method that Bruce descibed earlier, I usually make sure that I can always hear an increase in RPM's when the line is pinched. From there go to the LSN and do the pinch test and adjust for a 3 second increase in RPM then dies. Remember a little rich is always better.