Stage 2 Engine Development and Modification

Stage Two Harley-Davidson engines involve Stage 1 changes plus changes to some internal "bolt-in" engine components. These "bolt-in" modifications include camshafts and milling of the heads to increase compression. Some special tools and knowledge of engines is required to perform stage two modifications.
These modifications will provide from 60 to 80 horsepower at the rear wheel of a late model 80 CID Harley-Davidson big twin Evolution engine, depending upon the condition of the engine and the components used.

All the Stage One parts plus the parts listed below can go into a Stage Two engine. The components listed have all been tested on Harley-Davidson engines. When installed and tuned properly, these components will improve the rear wheel horsepower of your big twin engine. Items that are not listed here have not been tested or do not improve rear-wheel horsepower of your motorcycle. An example of not being listed are drag pipes. Drag pipes, even properly tuned, will not improve the street performance of your H-D.

Camshafts

Some of the most popular cams for use in Stage 2 engine are listed below with an approximate grouping of cams with similar specifications and performance.

Bolt-in Camshaft Selector
EVOLUTION

Bolt-in Camshaft Selector
TWIN-CAM 88/95

Any camshaft with with a duration under 250 degrees and lifts below .500 can be considered bolt in. Extensive testing by Jerry Branch (Branch Flowmetrics) indicates that any group of camshafts with similar lift, duration and lobe separation angles tend to perform in similar fashion. To attempt to identify and test every bolt-in camshaft would be time consuming and expensive. The Motorcycle Performance Guide staff has reviewed J. Branch's results and agrees with the results. In practical terms, this means that the Crane 300 and EV-13 will provide about the same power, so goes the Crane 316 and EV-46. This also means that you will see only minor differences between the EV-13 and EV-27.

Need to find a cam to meet your specifications? Look through the Motorcycle Performance Guides complete list of Harley-Davidson camshafts for BIg Twin, Sportster and Twin Cam 88 engines.