If it an all of a sudden thing, it could be a stuck/broken powervalve. Sorry I do not have jetting specs for you. Also check your compression.
Chris
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94 Husky 360 2 stroke, Street legal,(gotta clear my throat now)! Ported engine, FMF pipe, kehin PWK carb, full knobbies, Pro Action Showa suspension, Pro tapers. 50HP