Engine Performance Dyno Runs
Technical information on Stage 2 engines for Harley-Davidson motorcycles.
Stage Two Engine Basic
The Stage Two Basic engine represents a more extensive
approach to improve engine performance with bolt-on components and a bolt-in camshaft.
Most people can perform these modifications themselves. Modifications over stock engine
are underlined in the list below. The estimated cost for these modifications ranges from
$700 to $1000. The performance return for these changes can be large for the dollars
spent. Increases up to 30 HP and 20 Ft.Lbs of torque can be seen on some bikes.
The major changes for a Stage Two Basic engine over the Stage One Advanced is the addition
of a Crane Fireball 310 camshaft. The original cam bearing was removed and replaced with a
Torrington. To speed the installation of the cam, Crane Time-Saver push rods were used.
These push rods allow you to cut out the old push rods and install the new ones without
removing the rocker boxes.
Testing on the Stage One engine with a Dyna 2000 ignition module produced very poor
results. The addition of the Crane HI-4 ignition module was used. The HI-4 allows complete
tuning of the advance curve andlet the engine take advantage of the higher RPM range of
the new cam. The rev limiter on the ignition module was set to a very conservative 5800
RPM. The maximum RPM range for a Stage II is 6200. A maximum of 70 HP occured at 5500
RPMs, with maximum torque of 78 ft. lbs. at 2600 RPMs.
The dip in the HP and torque curves is likely due to the CV carburetor. A different needle
or changing to an after-market carb should smooth the curves. A basic stage two engine
does not include the additional $350 to $600 it would cost to buy the carb.
Ignition: Stock H-D
Crankshaft and Flywheel: H-D
Intake Valves: Stock Diameter
Exhaust Valves: Stock Diameter
Valve Springs: H-D
Compression Ratio: 8.5:1
Cam: Crane Fireball 310
Pushrods: Crane Time Savers
Carb: Stock CV w/ThunderSlidet Kit- Idle Mixture out 3.5 turns
Carb Jetting Information: Slow Jet 48
Air Cleaner: UniFlow with modified HD air box
Ignition: Crane HI-4
Ignition Timing: 32° BTDC
Coil: Stock H-D Dual File
Pipes: Stock H-D header pipes with modified Cycle Shack Slip-Ons
Dyno Tuning Facilities: CycleRama,
Pinellas Park, FL. (813) 546-0889