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Archive for May 8th, 2009

Twin Cam 96

Twin Cam 96

UPDATED: April 24, 2017Added a tab “Engine History” on the blog home page with updated V-Twin engine history including the Milwaukee Eight.

A little over a year ago I wrote about the history of the Harley-Davidson engines.  It’s one of the articles that gets a lot of attention/views from across the blogosphere so I thought it might be appropriate to update the post with some newer information.

The Twin Cam 96 was released for the 2007 model year in August 2006. Although the engine was the successor to the Evolution engine (“Evo”), they share a number of characteristics with nearly all previous HD engines. Both engines are a V-twin configuration at 45 degrees, are air-cooled, and control valve timing with push-rods. The crankshafts have a single pin with a tongue and fork arrangement for the connection rods. These are sandwiched between a pair of flywheels.  The HD Twin Cam 96B engine was released at the same time and is currently used on all softail models.  The TC96 is approximately 1584cc. The motor company has released Screamin’ Eagle models named TC103, a 103-cubic-inch (1,688cc) which is used in the 2009 Tri-Glide Ultra Classic (Trike) and the TC110, a 110-cubic-inch (1,803cc) in the 2009 CVO models (Fat Bob; Softail Springer; Road Glide; Ultra Classic Electra Glide).  The TC110 comes in an upgrade kit for the TC96.

It’s been speculated that the Motor Co. moved to the Twin Cam not because the Evo had reached its power limits as a design, but because HD could not prevent other manufacturers from making clones of the design. With the Twin Cam, HD was able to preempt cloning via the U.S. Patent Office, thereby making it a lot more difficult and expensive for the aftermarket vendors to compete with the Motor Co. in the development and sale of upgrades or complete motors.

In order to comply with the increasingly-stricter EPA standards, all TC96 equipped Harleys come from the factory tuned very lean, which in turn creates a great deal of heat.  All ‘07 and later Big Twins are equipped with Electronic Fuel Injection (EFI) and 02 sensors for closed-loop operation, allowing an extremely lean tune to be safely, and consistently achieved. This has been a topic of much discussion in the Harley world, as many have commented that the excessive heat makes the TC96 too uncomfortable to ride in stop and go traffic, or in the heat of the summer. There are also concerns about heat’s impact on the longevity of the engine. To help combat this many owners re-tune their engines, run synthetic oil or add an oil cooler; and HD developed a “Parade” mode in which one cylinder shuts down on the Twin Cam to prevent damage to the engine.

Sources: Answers; Harley-Davidson; Wikikpedia; Shop Manuals

Photo courtesy AnimatedPiston.

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FreedomThe good news is that motorcyclists in Washington State survived another year of legislative damage.  John Davis of Northwest Cycle Report provides a post mortem blog of the Washington State legislative session.  Below is a brief sample:

HB 1403 (Addressing the detection of motorcycles and bicycles at vehicle-activated traffic control signals.) got caught up in the wrangling at cutoff in the house and did not see any floor action. This could have meant that we were going to be required to wait until next year to try to get SB 5387, the companion bill for HB 1403, brought into play in the senate. The lobbyist for the Bicycle Alliance of Washington (BAW) went to work looking for a bill with traction, related to motorcycling or bicycling, that the traffic signal language could be appended to. He managed to find an innocuous (in his eyes) little technical correction bill that might work. Here is where it gets to be fun. The bill he found was SB 5482.”

“Texas” Larry Walker, the Government Relations Specialist in the Washington Road Riders Association provides the commentary and overview.  You can read more of the legislative details HERE.  I’ve found that Northwest Cycle Report goes to great lengths to provide informative and high quality information in their writing.  Check them out.

Photo courtesy WordPress Freedom theme.

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