Relief Tube Nipple for Singles 1926-1934 and D-Models

Until 1935, all models from Harley-Davidson used only a single oil pump for engine lubrication. (The Knuckleheads were the first with a recirculating lubrication system.) Engine oil was a consumable item and was regularly topped up. Much of the oil burned in the engine anyway, and the remainder collecting in the crankcase was periodically vented to the outside through a breather tube. This tube was mounted in the crankcase using a special union nut. The below sleeve nut fits all single-cylinder models from 1926–1934 and D models (750 cc, late 1928–1931).