The changes required consisted of removing the flaps and tail braking parachute, fitting a fixed, instead of retractable, monowheel and raising the height of the canopy.

With a change in the Standard Class rules, the 201B of 1969 introduced a retractable gear and a water ballast system as an option, with one 25-litre bag per wing located before the spar, with valve and dumping orifice on the fuselage underside.

Other improvements in the B variant were moving from upper and lower dive brakes to only longer upper surface dive brakes, a larger stabilizer for better low-speed handling, PVC foam sandwich core for the wing (instead of balsa) to increase durability and profile accuracy, increased gross weight and higher operating speeds.

The canopy is unique in that it has a catch that enables the front to be raised by 25mm (about 1 inch) in flight to provide a blast of ventilating air instead of the more conventional small sliding panel used for this purpose.

Great care is needed to ensure the pins are pushed in and locked at the bottom as they have been known in rare cases to come loose if not installed as such.