I agree with Ryan, I don't think there's any way that your not going to have to pull the carbs a few times to get it "perfect". Pulling the air box gives you quite a bit of room, and after having them off a couple of times you'll get pretty fast at it. I also was thinking that the mains are small if anything, especially if the previous owner was riding a very high elevation in Colorado and assuming that your riding at a fairly low elevation. Like I said, my cousin rides mainly between 4000-6000ft, huge difference from the lower elevations that most on here ride. For example, you'll see most on here running Vipers with pipes on them talk about having around 165 mains. I'm running the stock 156.3's in mine and am still a tad rich even with the Flo-rites in the dash. Definitely find out what elevation your going to be riding at, along with average temps (theres a big difference between 30 F and -20 F), that helps a lot in getting a starting point. Do several plug/piston wash checks on the bottom, mid, and top end. Plan your first couple of rides with the mind set of all your going to get to do is tune on the sled. Bring everything with you to be able to pull the carbs, change jetting, and re-test. You may also have to play with the fuel screws' setting if you have a lean bog when first hitting the throttle. If you get them up to 2-1/4 turns I would go up a size on the pilots and start at 1-3/4 again. On the needles, raising the needle/lowering the clip makes it richer, lowering the needle/raising the clip makes it leaner. I would make the first ride and see where the jetting is at and then go order some jets if need be. Order two or three sizes of mains going in whatever direction you need to go, throw the set in that's your best guess on being right, and then test and go from there. It's better to sacrifice a couple of the first rides doing this than to ride it blindly and end up burning it down (read about people doing that quite frequently). I actually enjoy tuning on the jetting and clutching, the first rides usually don't have good snow to really play on anyway, just enough to ride the trail. I used to not have a heated shop either (still don't, but my uncle does now) to work in, just get a small heater to warm your hands so you can feel them again, lol, a real PIA. Cold hands + gas = really cold hands! lol Ofcourse, be careful about putting gas soaked hands in front of a propane heater.
