Stage Three Engine Development

When you already have a 95 HP engine, how do you proceed when making additional changes? If you are smart, you do it in small, incremental changes that you can verify along the way. The goal of 118 HP from an 80 Cubic Inch Harley-Davidson engine may be pushing things a bit, but there is an actual chance that it can be done.

The current 80 CID engine using stock Harley-Davidson cases, cylinders and heads is able to produce 95.3 Ft.Lbs. of torque at 4700 rpm's and 95.3 Horsepower at 5700 rpm. The power comes on unbelievably strong between 4000 and 6000 RPM. the first step in moving the horsepower up by 23 ponies was to check a few things on the current engine. A quick run on the dyno confirmed that peak HP readings had not changed, but with a couple of thousand miles on the engine, a close inspection of the top end of the engine seemed in order. Before the engine was disassembled, a compression test was performed on the engine. The results of this test told me that more power was available in the engine. 195 PSI in one cylinder, 180 in the other. A shot of oil the 180 cylinder brought it back up to 195. Was the problem wear or an assembly problem? Only the tear down would tell.

As the top end of the engine was taken apart, everything was inspected for damage and measured for wear. Special attention was paid to the pistons, rings and cylinder bores. With no signs of wear on any of the parts, the measuring took place. A small difference in the ring end gaps between the front and rear cylinders was found. This would explain the difference, but now how to eliminate it now became the issue. Re-installing the rings was out of the question and installing another set of rings could leave us with the same problem again. A quick review of the parts books reveled rings by Perfect Circle, a gapless ring. This should eliminate the problem, and the company provides a no leakdown guarantee.
While looking for ideas for improving performance, a brochure from One Cryo  on cryogenic tempering came to my attention. Normally any sane person would not believe claims of increased performance and durability by 'freezing' an engine, but you don't build high horsepower Harley-Davidson engines by picking up pieces at your local wrench's shop. This idea sounded so outrageous that it had to be a complete hoax or absolutely true. It was actually fairly easy to confirm that the cryogenics treatment is a form of tempering the metal. We all know that tempering is a good thing, so time to talk to Cryo One. A few discussions with the Cryo One people, it was decided to cryo treat the cylinders and pistons in an effort to reduce some of the friction and attempt to improve the thermal stability of the cylinder bores. The Cyro One people do not promise horsepower, but they do guarantee satisfaction with the cyro process. The number of people who attest to the effectiveness of the treatment is impressive.

Stage Three Engine Components

Year: 1994
Model: EVO
Bore: Stock (3.500")
Stroke: Stock (4.250")
Displacement: 1340cc (81.8 CID)
Cases: 1997 H-D
Assembly: Owner
Crankshaft and Flywheel: H-D
Heads: H-D
Porting: CycleRama, Pinellas Park, FL. (813) 546-0889
Intake Valves: Diameter (1.940")
Exhaust Valves: Diameter (1.615")
Valve Springs: Crane
Compression Ratio: 10.5:1
Pistons: JE 10.5:1 [Cryogenic Tempered]
Piston Rings: Perfect Circle
Cylinder Deck Height: 0.000 inches
Head Gasket Thickness: 0.030 inches
Cylinders: H-D [Cryogenic Tempered]
Cam: Crane Special Grind - 268º intake 272° exhaust w/ .600 lift
Valve Lifters: H-D stock [Cryogenic Tempered]
Pushrods: Crane Time-Savers
Carb: Mikuni HSR-42
Carb Jetting Information: 185 Main
Manifold: Modified Mikuni
Air Cleaner: None - Velocity Stack
Ignition: Crane HI-4
Ignition Timing: 33.5° Maximum Advance
Coil: Crane
Spark Plug Wires: Magnecor
Spark Plugs: H-D Gold
Pipes: Cycle Shack Slash Cuts - No Baffles
Dyno Tuning Facilities: CycleRama, Pinellas Park, FL. (813) 546-0889
Engine Oil: Royal Purple 20w-50
Engine Gasket Set: James Gaskets