Stage 2 Modifications
Building a 74 horsepower 1340 Evolution engine

Performance and Technical information on Stage 2 modifications to a Harley-Davidson 1340 Evolution motorcycle engine.

Building the ultimate street bike engine
or
How to get 74HP from your 1340 Evolution engine.

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Your carburetor is re-jetted, a free flowing air cleaner is in place, you have the perfect exhaust system, and the ignition system has been upgraded. If you have made these Stage 1 changes to your bike and are still looking for more power, you may be ready for a Stage 2 engine, a performance camshaft. You must limit your choice to "bolt-in" cams unless you are willing to change pistons, change valve springs or otherwise modify your heads. Those changes require significant time and money.

There are many companies out there that are competing for the dollars that Harley owners are willing to spend on their bikes. As an owner, you will be bombarded with a vast array of promises, claims and inaccuracies in an effort to get your money. Reading between the lines on many of the performance claims can be bewildering.

Does the Harley-Davidson world need another bolt-in camshaft engine modification article? We decided it does, since the results obtained by the engine upgrades listed here provided significantly better results than those documented by the popular magazines aimed at the V-Twin crowd. The Motorcycle Performance Guide staff continues to obtain better results than the "experts" in the press.

How to build your own Stage Two engine

Stage Two engines do not involve any internal changes to the engine other than replacing the camshaft and camshaft bearing. All modifications are made by bolt-in changes. Some special tools and training is required to perform these modifications. Unless you are a very good mechanic, it is recommended you find a competent shop to install the camshaft and bearing. For those of you that want to install the camshaft yourself, Motorcycle Performance Guide has created the step-by-step instructions for installing a camshaft.

Over the past several years we have installed and tested many manufacturers components. The list of parts used in building the ultimate 'bolt-on parts' engine is the end result of this testing. The best and least expensive of the individual components was selected an tested as a single package. The fact that virtually all the parts used for the project are from Harley-Davidson is a coincidence. There was no plan or idea to use mostly Screamin' Eagle parts for this project.

All the parts used are readily available through your Harley-Davidson Dealer. The components were installed and tested on a 1997 FXD Dyna Super Glide. No special tuning was performed to achieve the results listed. All components were installed according to the manufacturer instructions supplied.

  • Building your Stage 2 engine
    Stage 1 improvements must be in place
    Install the camshaft and new Torrington cam bearing
    Change Oil and Filter
    Install new spark plugs
    Road test the bike
    Dyno Tune the bike

The results of the Dyno testing are excellent as this bike's performance continues to improve. The test results showed the engine producing 73.9 horsepower @ 5950 RPM and 78.1 ft. lbs. of torque @ 4100 RPM. This was another 10 horsepower increase over the Stage 1 results. This engine is now producing 20 horsepower more than a stock bike. Not bad for the small investment required to get these results.

The results are due to a well matched set of parts being bolted-on to the engine. Seems that a little of that money the Dealers send back to Milwaukee is going into engine performance research.

The ability to create the same results with other manufacturers parts is a distinct possibility. There is an optional parts list of components that should perform as well as the parts tested. Please be aware that the parts listed in the Optional Stage 2 parts list have not been dyno tested unless otherwise noted.

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Still not enough power for your needs? We decided to find out what happens when you take the Ultimate Stock Engine and make it a Stage 3 bike. There are more surprises ahead as we continue to step up the power in our "Ultimate Engine"  modifications series of articles. In the next upgrade, we bolt on a set of the new Screamin' Eagle 1340 EVO performance heads.

 

The Parts List for Bolt In Stage 2 Performance
New parts cost $252.95 plus tax.
Maintenance parts cost $51.00 plus tax.
Dyno Tuning costs estimated at $200.00 plus tax.

Camshaft

Andrews EV-46 camshaft
$158.00 list price - Street price is around $120.00
Torrington B-138 cam bearing
$10.00 Street price
Nose-Cone gasket
$8.00 from your local dealer
Screamin' Eagle Adjustable Pushrod Kit - Chrome Moly
Harley-Davidson Part Number 17900-87
$76.95

Other Items

Harley-Davidson Double Platinum Spark Plugs or H-D Gold Spark Plugs
Harley-Davidson Oil Filter
Mobil 1 15-50w Synthetic Motor Oil (3 quarts)
Royal Purple 75w-90 Synthetic Transmission Oil (1 quart)
Harley-Davidson Chaincase Lube (1 quart)

The Horsepower Gallery provides an extensive list of bikes , the power they produced and the major engine components.