1935

The Year Our Motorcycles Cleaned Up Their Act

In 1934, Royal Enfield unveiled its first OHV motorcycles with fully enclosed and automatically lubricated valve gear - the 150cc Model T and 250cc Model S. A welcome change from manual lubrication systems where riders had to pump the oil by hand and splattered grease left its impression on their trousers.

Royal Enfield was one of the first British manufacturers to produce fully enclosed and lubricated overhead valve gear, a significant leap forward in motorcycle design.

It cleaned up the looks of the motorcycle and, just as significantly, reduced its owner’s laundry bills!

In the beginning, the engines of pioneer motorcycles had no automated lubrication system so riders had to remember to pump the oil by hand while riding or risk seizure.

In the beginning, the engines of pioneer motorcycles had no automated lubrication system so riders had to remember to pump the oil by hand while riding or risk seizure. This was certainly the case with Royal Enfield’s original 1901 motorcycle.

These engines operated on the total loss principle - used oil was burnt off after lubricating the crankshaft, bearings and cylinder. Poor running and a smoky exhaust resulted from an over-zealous owner pumping too much oil into the engine.

The advent of the automatic mechanical oil pump in the 1920s was a welcome advancement. This circulated oil around the engine’s bottom end without any input from the rider. However, on overhead valve (OHV) models, the valves and rockers were uncovered and received no lubrication. Consequently, the rider had to stop from time to time to apply much needed squirts of grease to the rocker gear.

They were soon followed by the Model LO 500 Bullet which had a unique but short-lived fully-enclosed 3-valve cylinder head featuring two inlet and one exhaust port.

Well-greased valves and valve springs oscillating up and down several thousand times per minute was fascinating to watch but had two major drawbacks - rapid wear caused by exposure to the elements and grease-splattered trousers for the rider.

In 1934 Royal Enfield unveiled its first OHV motorcycles with fully enclosed and automatically lubricated valve gear - the 150cc Model T and 250cc Model S. They were soon followed by the Model LO 500 Bullet which had a unique but short-lived fully-enclosed 3-valve cylinder head featuring two inlet and one exhaust port.