Here are the specs for the MX Sprint with a Rotax 477, facts weren’t available for the Original MX. I would suspect the Original flies slower and weighs less.

POWERPLANT:
      PowerPlant.........................1 Rotax Model 447
      .................................Twin Cylinder, Two Cycle
      ...........................436.5 cc, 40 hp @ 6500 rpm
      Recommended TBO...............................250 hr
      Propeller........................................66 in x 34 in
      Length.................................................18 ft 1 in
      Height.................................................8 ft 10 in
      Wingspan............................................28 ft 0 in
      Wing area...........................................156 sq ft
      Wing loading..................................3.36 lb/sq ft
      Power loading.................................13.12 lb.hp
      Seats..............................................................1
      Minimum flight crew........................................1
      Empty weight...........................................250 lb
      Useful load...............................................275 lb
      Payload w/full fuel....................................245 lb
      Max takeoff weight..................................525 lb
      Fuel capacity.....................................5 U.S. gal

   PERFORMANCE:
      Takeoff distance, ground roll......................65 ft
      Takeoff distance, 50 ft obst......................200 ft
      Rate of climb......................................900 ft/min
      Max level speed, sea level......................54 mph
      Max operating altitude.........................14,000 ft
      Landing distance
           50 ft obstacle (with brake)...................200 ft
      Landing distance
          ground roll (with brake)..........................60 ft

   CRUISE PERFORMANCE CHART:
   (Speed/Range at sea level with
          4.8 gal. usable fuel)
  @ 55% power(5000 rpm)...............44 mph/84 mi
  @ 65% power(5300 rpm)...............47 mph/84 mi
  @ 75% power(5500 rpm)...............50 mph/80 mi
  @ 100% power(6500 rpm).............54 mph/52 mi                  

   FUEL FLOW:
      @ 55% power ....................................2.5 gph
      @ 65% power ....................................2.7 gph
      @ 75% power ....................................3.0 gph
      @ 100% power ..................................4.5 gph

   LIMITING AND RECOMMENDED SPEEDS:

      Vx (Best angle of climb).......................33 mph
      Vy (Best rate of climb).........................36 mph
      Va (Design maneuvering)......................48 mph
      Vne (Never exceed).............................65 mph
      Vs (Stall, power off).............................24 mph
      Landing approach speed.....................
                                (1.3 Vs)..........31 mph