I have a 2001 XCSP 600 that was as cold blooded as heck. It has the Mikuni TM38 carbs on it. I did some playing and research on my own along with advice from you guys and found a happy solution. It isn't perfect yet but is 95% better. I always had to babysit the sled to warm it up. Now I don't and I have started it in single digit temps. All you need to do is up the Idle/Starter Jet one size(mine was 140 and now is 150). The Polaris dealer that I ordered it from told me there's no way it will work and that I needed Pilot jets. I told him to just think about it. The Idle jet controlls fuel flow at 0-1/8 throttle. if its cold blooded, you need more fuel. Now I just have to tune my mixture screws a little bit until its perfect! I hope this helps someone else with the same frustration!