Harley Davidson “Serpent”

The ARC2 works along with your existing engine management computer to extract peak performance from your engine.



Split Second ARM1 and EGO1 mounted on the “Serpent” Bike



The ARM1 mounts under the right hand control cluster on the handlebar. 
It is very light and stays in place using the Velcro that comes with the kit.



The EGO1 mounted in the Supertrapp muffler seems to be the likely spot, 
do to the ground-clearance and other clearance problems.


The “Serpent”, a custom that has taken over 30 months to build, started as a 1966 Shovelhead basket case. Because motors can burn up when they run lean it was felt that for a motor of 96″ displacement there would be too much doubt as to the mixture that was running at any given time. Dialing in a beast like that benefits from knowing for sure that you are running a mix that won’t detonate or melt down your moving parts. So a search was made for a fuel mixture analyzer that would work with the bike. That search led to Split Second of Santa Ana, CA.

Using an Air/Fuel mixture monitoring system you can dial in a bike with absolute certainty. To help with the dial-in, a Dial-A-Jet secondary circuit was added to the S&S Super E carburetor. Using the Dial-A-Jet with the Split Second system it was possible to dial the bike richer or leaner and observe the results. Jetting is an art, not a precise science, but it was possible to find the ideal point where the bike runs smoothly, avoiding running lean under throttle.

It took some thinking to find the right spot for the EGO1 gas analyzer. Because the header pipes and 2-into-1 were custom built by Mike Scraggs of California Performance Iron it was not a good idea to drill a hole in that assembly. It is such a fine job (the front pipe fits between the motor and frame without needing to be crushed) that re-creating it would not be easy. Instead, the Supertrapp seemed the likely spot. Because of ground-clearance and other clearance problems the sensor was tightly fitted into a precisely drilled hole at the location shown, and TIG welded in place. It is possible to get away with mounting the sensor this far from the motor because the sensor is heated electrically (four wire) and this compensates for cooling of exhaust gases, providing as well a calibration standard.

After using the Air/Fuel mixture sensor to dial in the bike, the sensor serves to warn of undesirable conditions when changing altitude or other atmospheric conditions cause richer or leaner burning. It gives a strong sense of confidence that this beautiful bike will give many years of pleasant riding.

I also maintain a page at http://www.fargonasphere.com/serpent/

Thanks for providing your excellent product!

Nelson Johnson (Spider)