From the October 1939 Issue of Motorcyclist Magazine
Styling to correspond with 1940 automotive streamline trends, and refinement of all models to better meet ultra demands for speed, durability and economy constitutes the keynote of Harley-Davidson Motor Company announcements for 1940. As the curtain is drawn back on their offerings for the next year notable features are: instant gas reserve valve; speedlined footboards; chrome nameplates; ribbed crankcase on big twins; streamlined tool box on big twins; tubular front fork on 45 and servi-car; deep-finned aluminum heads standard on 80 twins and 45 WLD, available on 74; front forks heat treated; improved oil distribution in cylinders of 45, 61 and servi-car motors; new big twin crank pin and rollers; cast front wheel brake drum on big twins and servi-car rear wheels; more 61 OHV horsepower; transmission and clutch improvements; copper-flange terminals; improved interchangeable wheel hubs; 5.00x16” tires and rims available; new saddle-top leather; many servi-car advancements; vertical rod antenna and improved vibrator on radio police model; new accessory groups; new color scheme and beautiful color options, and lower prices.
One sweep of the eye tells anyone that the 1940 Harley-Davidsons are new. New colors, deep-finned aluminum heads, chrome nameplates, streamlined footboards, and ribbed crankcases are the first features to catch the attention. Then other items begin to arouse the curiosity; among these are the reserve gas supply control, improved forks, front wheel brake drums, etc.
Let us consider the improvements feature by feature.
For a starter, what is the knurled cap just ahead of the left tank filler cap on all models? It’s a gas control valve that not only shuts off the gas but makes reserve gas instantly available. No more burned hands and fingers as a rider fiddles around hot cylinders in traffic, in the dead of night, or any other time, to turn on reserve gas. When screwed down, the entire gas supply is shut off. When unscrewed to end of thread, the main supply is being used. When that is exhausted, the rod is lifted up and the reserve gas flows on to the carburetor. The reserve gas in the big twins is about three quarts, and about a gallon in the 45 twins. The extended rod is warning that the rider should hie himself to a filling station at the first convenient opportunity. The rod is held in reserve position by a spring-loaded Neoprene (synthetic rubber) packing.
Now riders can really use all their main supply of gas before buying more. Because of the inconvenience of the old system, riders hesitated to get down to their reserve supply, and when they pulled up to a gas station really had to guess how many gallons to ask for. Usually, they ordered too much with resultant gas wastage and the incurring of a dangerous fire hazard.
The entire gas control valve mechanism is enclosed in the left tank and cannot leak. Should it become necessary to do so, the valve mechanism can be easily and quickly removed.
The 61, 74 and 80 twins, which have right and left gas tanks, have their tanks interconnected at the bottom with a looped, standard copper tubing gas line. The same gas level is maintained in both tanks as though they were one. The position of the gas valve controls the gas in both tanks simultaneously.
It’s good-bye to the old familiar tank transfers. With 1940, they are superseded by tear-drop design, chromed, brass nameplates gracing right and left tanks. The front of the plate clips into a bracket on the side of the tanks, and the opposite end is held securely in place with a screw. The name Harley-Davidson is debossed into the plate, and the lettering is red. Two streamlines, one above the name and the other below, are debossed in black and ornament the new nameplates.
A further advantage lies in the fact that there are no transfers to bother with whenever it may be necessary or desirable to re-enamel.
The old familiar rectangular shape of footboards has been streamlined into semicircular design. Not only is appearance served, but in riding position more of the rider’s feet contact the surface of the boards.