Fooling with Fuel: Cobra FI2000 Motorcycle Digital Fuel Processor

We knew some sort of fuel-injection remapping would be needed in our August 2003 exhaust system comparison. The DynoJet Power Commander used to be the only game in town, but Cobra has come up with something else, something simpler. It's called the Fi2000, and it's basically a development of the Techlusion digital fuel-processor box designed by DynoJet founder Mark Dobeck.

The Fi2000 works on a simple premise. Most bike modifications -- pipes, filters, ignition advancers -- will make an already lean-running model even leaner. (Lean means that the fuel/air mixture has less fuel and more air than desirable; a rich mixture has too much fuel. Up to a point, a lean mixture will make a bike lose power and run hot, while a rich mixture will start to hurt power only when the imbalance becomes excessive. The theoretically ideal ratio is approximately 14 parts air to one part fuel, though maximum power is obtained near 12:1.) Back to the Fi2000: Assuming all you need to do is add fuel -- making the mixture richer to compensate for the modifications -- the design of a device to accomplish this becomes radically simpler.

The Fi2000 connects with just four wires on the Mean Streak: power, ground and two wires leading to each cylinder's fuel injector. By "listening" to the injector signal, the Fi2000's internal processor determines how fast the engine is turning and how long the injectors are open -- they are normally closed and spray fuel into the inlet tract only when switched on. Depending on how the Fi2000 is configured, it can hold these injectors on for longer than the standard computer is programmed to allow, which makes the mixture richer.

You determine how much fuel enrichment takes place by turning two small potentiometers under a rubber plug. One controls high-engine-speed functions, the other idle and low-speed functions. Cobra delivers the Fi2000 set up for its own pipes, but the box has sufficient range to work on a variety of pipes, or even on a stock bike. Our setup recommendations follow Cobra's lead by referencing points on a clock. Straight up is 12:00, pointing right is 3:00 and so on. There are no markings on the dials themselves.

On the Mean Streak, the Fi2000 performs flawlessly and only creates problems for itself when confronted with pipes that need a slightly leaner mixture to run well. Remember, the Fi2000 can only make the bike run richer (or exactly like stock), never leaner. For most pipes, the Fi2000 will do the job just fine, and at $200 it's a sweet deal to boot.

Cobra Engineering

Marc Cook is a regular contributor to _Motorcycle Cruiser and our sister magazine _ Motorcyclist _ as well as other automotive and aviation publications._

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