The Skylark was built in Melbourne, Berwick actually and the one you have looks to be a fairly early one as it has the Victa twin flywheel on it. I can't tell from the pictures but if it has cast iron barrels then it is definitely early. There were over 400 produced and most were sold to the USA, the later units had a specially wound coil, with the flywheel off the early Victa 125 as it gave better spark, these had their fins machined off as there was no need for the cooling fan. The were 320cc and the only parts from Victa were the ignition flywheels and some ignition internals, the pistons were Yamaha and the con rods from Kawasaki, the reed valve is also Yamaha. The carbie is a Tillotson pump type from a Ski-Doo. The crankshaft was purpose built for the engine and there was a very small batch that had breakage problems as the incorrect steel for the shafts were supplied and the problem wasn't discovered until they failed in service. They were rated at 18hp with a weight of 25lbs, they were originally conceived due to the inventor buying a Skycraft Scout from Ron Wheeler in about 1975/76 and finding that the Pixie engine which WAS a converted Victa engine couldn't get the aircraft off the ground. The Skylark Aero Twin was the first purpose built Ultralight Aircraft engine in the world, what you have is a piece of history from the early days of the Minimum Aircraft movement in Australia. The Victa twin ignition system was replaced with a specially wound coil and 125cc flywheel because the Victa twin system was a piece of crap.
