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The tank inside the tank

The tank inside the tank

Next stage on the way to Cannonball 2025: One of the outstanding parts on our 1928 J model is of course the tank, or rather the twin tanks, in many ways typical for American motorcycles of the 20s of the last century.

Back in the day most motorcycles were using total loss lubrication systems. The engine oil was not recirculated, but delivered to the engine and just got used up after doing its job of lubricating the moving parts. Some of it was dribbled onto the primary chain via the breather and from there into the primary cover.

So how was the supply of oil to the engine organised?

The first Harley-Davidsons up to 1914 did not have an oil pump, with the lubricating oil being gravity fed (drip feed oiling) to the engine via an adjustable needle valve. From 1912 on hand oil pumps were available, to be used when the load on the engine was higher than usual, as on long full throttle sections, steep inclines or when the sidecar was fully laden with your mother-in-law.

In 1915 Harley for the first time brought a mechanical oil pump to market, the "automatic oiler". It was factory preset for a sufficient oil supply in regular conditions. It still wasn't a circulation system, but under oiling wasn't a problem anymore. It was a big step though. Hand pumps were still in use, but the rider didn't have to worry all the time if he was starving or flooding the motor with oil. Too much oil is almost as bad as too little: power loss, oil slipping by the rings, oiled up plugs and caked valves weren't unusual.

What does all this mean for the tank construction?

The Harleys of this era had their oil tank and the hand pump integrated into the left hand gas tank. The main part of the gasoline lived in the right hand tank, the space in the left side not used for oil was for reserve. The oil compartment in the left tank had two functions then, it served the mechanical pump and the hand pump with the precious lubricants.

What's the condition of our "Flying Turtle's" tanks post removal?

We're happy to report that the Flying Turtle's tanks are in great shape, considering their age. Still, we'll have the right hand tank cleaned and coated, for some added protection.

If we had discovered major issues with the tanks though,

we'd have had the option of using a worthy replacement: the faithfully remanufactured tanks for IOE models and early flatheads in the Harley-Davidson lineup by "The Cyclery", sitting in our warehouse for emergencies like this.

What do we mean by "authentically remanufactured "?

Tanks by "The Cyclery" are being made like they were being manufactured a hundred years ago. Their components are being soft soldered. It worked then, and it works now, even if it's not as strong as modern day welding.

Is it okay to soft solder tanks instead of welding them?

The tanks by "The Cyclery" are soft soldered, using a lead/tin based solder. Which was state-of-the-art up until the 40s of the last century. The legendary Ernst "Klacks" Leverkus, influential motorcycling journalist, motorcycle tester, presumed inventor of the tank bag and initiator of the famous Nürburgring "Elefantentreffen" winter motorcycle rally, even in the Sixties asserted that soft soldering is the correct method to solidly repair a cracked tank, with the added advantage that even out in the boondocks it can be successfully done. In a long distance cross country race as the Cannonball possibly a deciding factor.

As a bonus the low temperatures of the process are easy on the tank's steel walls and prevent warping.

Is it necessary to specially treat the tanks?

We recommend using tank sealer to treat the insides of tanks (also available at W&W). Hairline cracks and pores will be filled and long term tightness will be improved. Reliable corrosion resistance is also assured.