I have my 39's in and just completed a rally. Early morning temperatures for the 4 days were was about 3 degree celcius = 37f. The altitude was 1340 meters. When I arrived I needed to turn the idle up slightly.
For the coldest morning, two pumps and it farted and died. Another 2, the same. Then I held in the starter and after about 3 seconds the one cylinder started to catch and after about 6 seconds it was running on its own.
Just out of curiosity, I let it run for maybe 10 more seconds then turned it off. It fired right up, no hesitation. I have found that even when slightly warm, it starts instantly.
For the other mornings, I had very little trouble starting it. I still haven't found a sequence to what works best. I have been experimenting with a combination of a few pumps and prolonged starter motor. The most pumps I gave were 6 and that didn't seem to help much.
My settings for my Adventure with a 08 990 Super Duke engine are;
Elevation @ home = sea level.
Pilot # 52
Needle Second groove from the bottom
Pilot Screw 1.25 turns out
Float Height 15mm
Rear Cylinder same as front, but main #142.
I often wonder where that road goes? And that, has usually made all the difference. Appologies to Mr Frost