I am new to 4 strokes, been riding and racing a CR500 for the last 15 years. Did a search and could not find any suggestions on jetting for cold temperatures. Some guys in our ice racing club do not rejet their 4 strokes for winter!!! We usually ride in -20c to -10c and have on occasion ridden as cold as -40c. I would like to jet for -15c to be safe but the manual does not have a handy dandy chart like the one for the CR500. I could spend some time with a calculator and get close but with all the knowledgeable guys on this site was looking for a starting point. BTW I only have about 3 hours on the 06 so it is barley broken in, bought a yellow one in spring but was too busy to ride until this fall, but the 2 times I rode it the bike was awesome. The CR500 has more power but the YZ450 is faster, there is only so much traction in the dirt, that might change on the ice though. Oh ya, the 3 hours of riding time on the 450 was in cold temps (about 5c) but it seemed to start really easy and run really well even on the factory 42 pilot, very little popping on decel. 1600 ft elevation. After reading all the posts of way to lean jetting I was amazed it ran so well at only 5c temperature. So what do you experts suggest for a starting point?