WHEN IT COMES TO CHOOSING AN ENGINE for his Medaza motorcycles, Don Cronin has form. Forget about a big Harley mill from The Motor Company, or the latest big-bore Triumph twins and triples. He’s used a 500 single with a ‘bacon slicer’ external flywheel that once powered a Guzzi Nuovo Falcone, a V-twin liberated from a Morini Camel enduro, and even a utilitarian two-stroke lifted from an MZ 300ETZ. So, when he wanted an inline-four for his latest project, he was guaranteed to come up with something different. And in a world of high-revving, huge horsepower fours, there’s nothing quite like a Nimbus.
Vacuum cleaner manufacturer Nilfisk branched out into making motorcycles way back in 1919, but the Nimbus we are interested in was launched in 1934. The unit construction 750cc engine featured an overhead camshaft. Just like the original MG sports car, the vertical camshaft drive to the bevel gears doubled as the armature spindle for the dynamo, which was mounted in front of the cylinder block. The lower half of the crankcase was cast in aluminium and carried a couple of litres of oil, but the upper half of the crankcase and the
