Harley-Davidson Lubrication

In the early days, engine lubrication was taken care of either by a drip feed, by which oil was dripped through a needle valve at a rate that could be adjusted by the rider, or by a hand pump, which one pumped a couple of times every few miles to keep the motor happy. The problem with the latter was that most riders, paranoid that the engine wasn't receiving enough oil, would overdo things and tended to over-oil it instead. The result was oil blow-by past the piston rings, carbon build-up overheating and premature wear. The only cure was an automatic oil pump, which Harley-Davidson introduced for 1915. Driven off the magneto drive shaft, the pump fed through a sight glass so that nervous riders could reassure themselves that all was well. The pump delivered 4psi, laughably low by modern standards. Though, at the time Harley-Davidson claimed it would feed against a resistance of up to 70psi. By the standards of the day, it was a precision piece of equipment, and if any pump was faulty, dealers were asked to return it direct to Milwaukee for repair.