Stage 1 Modifications |
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| Performance and
Technical information on basic modifications to a stock Harley-Davidson 1340 Evolution
motorcycle engine. Build
the ultimate in a stock bike engine
One of the first things most people do shortly after they get their new motorcycle is start to modify the engine. In the time honor tradition of Harley-Davidson, the first thing to go on most bikes are the stock mufflers in an effort to improve the sound. This is usually the first in a long list of changes to the engine. Changes to the carburetor and ignition system also rank very high on the first to change list. These changes are done to improve the performance of the bike. 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 stock engine modification article? I 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. How to build your own Stage One engineStage One engines involve no internal changes to the engine. All modifications are made by bolt-on changes to external components on the engine. These components include air cleaners, carburetors, exhaust systems and ignition systems. No special tools or training is required to perform these modifications, although it is recommended you are comfortable working on your own motorcycle. 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 and 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 except for the spark plug wires, which can be ordered directly through Magnecor. 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.
The results of the Dyno testing simply astounded us. The test results showed the engine producing 63.8 horsepower @ 5350 RPM and 72.5 ft. lbs. of torque @ 3650 RPM. Three separate runs provide identical results. These performance numbers produced where real. The results were so surprising that additional research was done to make sure that Harley-Davidson hadn't come up with new cam design since 1996. The stock cam is still the same Harley "N" grind that has been around since 1992.
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 1 parts list have not been dyno tested unless otherwise noted.
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 2 bike. There are more surprises ahead as we continue to step up the power in our "Ultimate Engine" modifications series of articles. |
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The Parts List for Bolt On Performance
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| Other riders have been
able to produce similar results: A 1998 FXD produced 66 HP and 78 ft. lbs. of torque with a stock engine. The only noticeable difference over the recommendations listed above is that the 98 bike used a Yost Tuners Kit in place of the DynoJet Re-calibration Kit and time was spent tuning the bike on the dyno. The ignition module had not been updated on this bike either. A 1998 FXSFB produced 62 HP with a stock engine, K&N OEM replacement air cleaner element, drilled out air box and stock mufflers with the baffles drilled out. |
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| The Horsepower Gallery provides an extensive list of bikes , the power they produced and the major engine components. |
