when i raced snocross, and ran c-16 in our mods, and before we had an enclosed trailer, we had a helluva time starting the sleds when it was cold. finally what worked best for us, was to take a car warmer and put it under the hood. then get ready or walk the track. and after 15-25 min they would start right up, then start it up every once in awhile to keep things warm. if it was really cold we would drape a blanket over the sled to help keep the heat in. hope this helps someone out!
Get a Grip and Rip