This is my wifes sled and it keeps fowling the plugs when first running the sled. I have made a point lately of warming it up generously but it still will fowl a plug on almost every cold start. Once a new plug is installed it seems to run ok for most of the day but still it isn't running correctly. Sounds like it is fuelling up or basically running too rich. Most of the time I only have to change one plug. Usually the centre one. Does this sound like jetting or could it be one carb is dirty? I'm thinking if it was jetting we should be having the same problem with more than one plug? I've have this looked at and paid about $150.00 with no results. Any suggestions or thoughts?