Hi Speedy,
Nice machine, it's a Briggs and Stratton 2 stroke made by the Japanese company Komatsu Zenoa in the late 80's. Briggs never made their own 2 stroke back then but enlisted the help of another company to make them. My understanding is that due to the "recession we had to have", these became not economically viable and as such the collaboration between the 2 companies ceased.
They are a brilliant little engine with heaps of power, Masport and Greenfield used the "Briggs" 2 stroke during the 88-89 era whilst Rover used the Suzuki, all in an attempt to compete with the locally made Victa 2 stroke. As a consequence of the recession they could not compete with the Aussie made Victa 2 stroke and as such they stopped using them on their mowers.
Cheers, Ted