Re: Small Engines cold air and Performace.
Yup... depending on the jetting it can be decent at 90 degrees outside, then you'll notice when it drops to around 60 the bike has this nice new found power,but around 30 it slows back down because the air is nice and dense but at some point the jetting will actually go lean enough to level off then it gets a little colder and it becomes lean enough to lose a little power.
I really notice that on my 1400cc intruder.... it's already mega strong, tons of torque, and I jet my carbs in the summer when it's in the three digits over here for 3 to 4 months. I jet it for making the most power in those conditions so it does get noticeably stronger when the temp drops down to the low 70's and stays this strong down to the mid 50's or so, but when it drops below 50 I'll notice that extra punch is gone, and by the time it drops into the 30's or less it's not quite as strong as it is in the high 90's. Being that the temp never stays that cold over here for more than a few days and it's back up to the 60's and 70's, there's no reason for me to re jet for the seasons.