KX10013,
Yes for winter riding and ice racing you will need to richen up your main jet. Your bike like a nice constant air:fuel ratio to be delivered by the carb. In winter the air is colder and more dense, hence it contains more oxygen (per volume). Since your main jet delivers the same amount of fuel, the oxygen(air) to fuel ratio will have too much of the air part making it too lean. A richer main jet will fix this. You will also want to raise your needle 1 or 2 (lower the clip). Its hard to say which main jet to run, but it would be safe to start out with 2 sizes up from stock and then do a plug run to see if it is correct. Have a look in the "jetting" section for tips on the propper way to do a plug run (chop). Hopefully somone with more direct ice jeetting experience will chime in. Hope this helps. Cam.
