plz go thru the fuel saving tips, placed somewhere @PW.
e.g. clean air/fuel filter, correct sp. plugs (make/model, spacing), good suspenion (wheel balancing/align/bearing/brakes i.e. no hinderance offered by any of them ), corect tire pressure, and of course good engine tuning/a-f setting of carb.
btw just curious, r u sticking with the general tires it came with or s/w to bigger wheels/tires
also i'd suggest change the filling station if u ve done all that is listed above.