Basic Stage one Engine Design
The Stage One Basic engine represents a simple approach to
improve engine performance with bolt-on componentst. 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
10 HP and 10 Ft.Lbs of torque can be seen on some bikes.
This dyno run was sent to us by Sam Weatherby from the Seatle
area. The dyno run was performed by Eastside H-D/Buell in Belleview, WA. This is the
highest performance numbers seen on a late model, stock cam bike. A maximum of 66 HP
occured at 4900 RPMs, with maximum torque of 78 ft. lbs. at 4000 RPMs. The HP and torque
curves for this engine combination was very smooth, with a broad torque curve over 70 ft.
lbs. starting at uder 2300 RPMs and extending to 4900 RPMs.
Year: 1998
Model: EVO
Bore: Stock
Stroke: Stock
Displacement: 1340cc
Cases: H-D
Assembly: H-D
Crankshaft and Flywheel: H-D
Heads: H-D
Intake Valves: Stock Diameter
Exhaust Valves: Stock Diameter
Valve Springs: H-D
Porting: None
Compression Ratio: 8.5:1
Pistons: H-D
Cam: H-D
Pushrods: H-D
Carb: Stock Keihin CV with Yost tuning kit installed
Carb Jetting Information: 180 main jet, 45 slow jet installed, needle 2nd groove
Manifold: Stock
Air Cleaner: Screamin Eagle K&N
Ignition: H-D stock
Ignition Timing: 32° BTDC
Coil: H-D
Plug Wires: H-D
Pipes: Stock headers with HD Slip-on Baloney cuts
Dyno Tuning Facilities: Eastside H-D, Belleview, WA.
