The Harley-DavidsonMilwaukee-Eight engine is the ninth generation of "big twin" engines developed by the company, but only Harley's third all-new Big Twin in 80 years, first introduced in 2016. These engines differ from the traditional Harley Big Twin engines in that there are four valves per cylinder, totaling eight valves, hence the name. It also marked a return to the single-camshaft configuration as used on previous Harley Big Twin Engines from 1936 to 1999. In addition, the engines all have internal counterbalancers, whereas Twin Cams were counterbalanced only on Softail models, where the engine was rigidly mounted.
107 and 114 and 117 engines
All engines have eight valves in two cylinders in the traditional V-twin configuration at 45°, are combination of air-cooled, and oil-cooled, and activate valves with push-rods. The model with a claimed is standard on all models, with the version making a claimed remaining as an option on some softails and all touring and trike models, and the is standard on CVO models with a claimed and rear wheel power of @ 4,870 rpm and @ 3,400 rpm.
In 2016, the Milwaukee-Eight engines became available on Touring and Trike models of the 2017 model year. The Softail models started using the Milwaukee-Eight the following year. The most significant change from the Twin Cam are the two extra valves per cylinder head which produce 10 percent more torque. The exhaust and intake flow capacity is increased by 50 percent over the Twin Cam models. Although weighing the same as its predecessor, both models of the Milwaukee-Eight increase in acceleration by 10% and 8%. Fuel economy is also increased, with percentages varying for engine and model.
Improvements
Harley conducted interviews in seven cities and over 1,000 people were asked to outline what they would like to see in the next line of touring bikes. These interviews resulted in the new Milwaukee-Eight engine. The biggest improvements people wanted to see was in the power, heat and vibration. Harley was able to increase the power while also keeping the range and consumption similar and in some cases making it even better. To deal with the heat issue, Harley reduced the exhaust gas temperature by 100°F, allowing for a more comfortable ride. They were able to make this possible by relocating the hotcatalytic converters further from the cockpit, as well as introducing a better water cooling solution. Finally, Harley looked at the vibration issues and decided to reduce the vibrations by 75%, in order to affect a balance between hardcore fans and new Harley owners.
Reception
Cycle World, like many other motorcycle magazines, was given the opportunity to test ride and review the Milwaukee-Eight engine. The reviews have been positive, and report a better ride quality, while still keeping the Harley feel. Cycle World's reviewer reported a noticeable reduction in the heat output from the engine, enabling the reviewer to ride more comfortably. The review concludes that the changes make this engine an improvement over its predecessor.
