All depends on what state of tune the bikes in. MC18's seem to like around 128-130 main jets (and the stock power jets) if running race pipes and a mod'ed air box. Both myself and Wayne tryed running richer only to find they hated it. Of course if youre running pre mix you will have to calculate what to add on to the 130m/j to get the same effect. With an air box 175m/js does sound very large but not unheard of.
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If I have to take the carbs off once more...