Remanufactured Harley-Davidson Evolution Engines - Evo Vs. Twin Cam

Harley Davidson Evolution Engine Remanufactured

Unless there is severe damage to the heads, all the valve seats are re-cut and checked.

Each remanufactured engine is hot-tested to Harley-Davidson standards. If it passes, it receives a one-year unlimited mileage factory warranty. After the running test engine was reman'd, it was packed for shipping back to Fullerton Harley-Davidson. We hired a reporter who snuck into the Harley-Davidson Capitol Drive facility in a box of parts and photographed the entire sequence of remanufacturing procedures.

We found this whole process fascinating. The remanufacturing system allows the factory to inspect the wear of many engines, determine how well they performed, and find their weaknesses. Since Twin Cam engines can also be remanufactured, it would be interesting to know which engines hold up better. We've always liked the Evo engine (and so does the aftermarket) for its simplicity.

We spoke to Scott Miller, the man in charge of the reman program for Evolutions and Twin Cams. He's also in charge of the new engine building program, including Evos, Twin Cams and big-inch Twin Cams. We quizzed him about wear and tear, what survives, and what fails. "We record and document failure codes," Scott said. Unfortunately, he couldn't tell us if the Evo lasts longer than the Twin Cam or what is weak or strong in their engines. "But I can tell you that if a rider is reasonable with his engine during use and changes the oil every 2,000 miles, he will get a lot more riding out of it."

He also told us many riders go for the $2,000 reman just to freshen up engines and have the components powdercoated for a much more durable and long-lasting finish. Before 1994, engines weren't powdered at all. He also pointed out that all the cosmetic components are replaced with new parts including chrome.

Enjoy this process. When our engine was returned, it was virtually new again.

We old builders avoided oversized valve guides because we were determined to make a set of heads last forever. We would carefully heat and tap out the old guide and pray the new stock guide would fit as tight as a boar's ass. The Factory knows the average rider won't put 200k on a given engine and two 200k engines would last most guys a lifetime, so the Factory pressed in a new set of oversized valve guides and assembled the valves and springs to the heads. We were taught that if the clips aren't inserted properly between the collar and the valve, disaster could strike. It's critical. Each cylinder is vacuum-tested to check for combustion chamber leaks.
We old builders avoided oversized valve guides because we were determined to make a set of
Next, we take you to the engine case station, where Denise and Jeff refit an entire engine. Since our original cases were not used, the original VIN and serial numbers on the engine crank cases were stamped into the new cases.
Next, we take you to the engine case station, where Denise and Jeff refit an entire engine
On the drive (or left) case Jeff pressed in the new Timken bearing race. It's interesting to note that late model Twin Cams don't run Timken bearings on the sprocket shaft, but shifted back to the old roller style from the Panhead era (like the ones used on the pinion shaft side here).
On the drive (or left) case Jeff pressed in the new Timken bearing race. It's interesting

Zipper's makes a kit to exchange the roller style bearings back to Timkens for Twin Cams. Harley is satisfied with the roller style even for their 110-inch Twin Cam engines. Jeff is also responsible for pressing in a new cam bearing. "The Evo cam bearing used in all reman engines is the most recent bearing used in Evolution production in 1999," said Scott Miller from the factory. "This is the same situation for any other common parts-they are always updated to the latest and greatest."