Hi,Narianu! Well,the auto-choke is very nice when it works correctly. Problem is if it sticks or opens late or doesn't open at all.Ha! Since it runs okay when you let it warm up for a while,why don't you just rev it a little on the stand to speed up the warm-up while the choke is on? In colder weather it takes a little longer for the auto-choke to release,and also you might find that the carb and choke need cleaned. For now,just warm it up a little longer. At 100 mpgs that isn't costing you much gasoline,right? Where are you from,anyway,and what kind(brand name and model and year is it)? don-ohio (:^)