Harley-Davidson Twin Cam engine

The Harley-Davidson Twin Cam engines are motorcycle engines made by Harley-Davidson since 1998. Although these engines differed significantly from the Evolution engine, which in turn was derived from the series of single camshaft, overhead valve motors that were first released in 1936, they share a number of characteristics with nearly all previous Harley-Davidson engines. Both engines have two cylinders in a V-twin configuration at 45°, are air-cooled (some touring models use liquid cooling for the heads), and activate valves with push-rods. The crankshafts have a single pin with a knife and fork arrangement for the connecting rods. These are sandwiched between a pair of flywheels.

The Twin Cam 88 was released for the 1999 model year in September 1998. The Twin Cam 96 was released for the 2007 model year.

The Twin Cam initially was not used in the Softail model family before the year 2000. This was due to the chassis design and vibration transfer to the Softail frame as a result of the direct (hard) mounting of the engine. Dyna models are "rubber mounted", damping the majority of vibration transfer to the frame and rider. Another reason was that the engine and transmission on a Twin Cam are directly bolted (but are still separate units) to each other, with the chassis seat post on a Softail getting in the way of a Twin Cam transmission case. As the company determined that a rubber-mounted Softail would affect the line's visual styling, Harley solved the issue by designing an engine variant known as Twin Cam 88B. It is basically the same engine as the original (now called "Twin Cam 88A"), but with a modified engine block design that incorporates twin chain-driven balance shafts. The Twin Cam 96B engine was released at the same time as the Twin Cam 96A model, for the 2007 model year, and was equipped on all Softail models until it was replaced by the 103 ci version.

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