Happy New year from Tail Gunner
This month we’ll talk a little about EFI piggy back units, cheap HP for the engine mods you have made. There are literally dozens of companies that make these products. Some have PC programs you can use to alter the air fuel ratios, and some have manual adjusting dials like a carburetor. You can spend boo coo bucks on these units, anything from a couple hundred to fifteen hundred or more. Harleys have either a open loop (’95-03) or closed loop (“04-present) EFI system. With the PC programmable products such as the Harley Race Tuner or Power Commander you make the required changes to your EFI MAP on your PC, then plug it in to the bikes ECU. The issue I found with these products is you spend a lot of time playing with different MAP settings before you get it right. And if you don’t have a dyno readily handy, then you may never get it just right. All the different exhausts, air cleaners, cams and ignitions make for way too many variables to experiment with for me personally. The piggy back units which simply add fuel under load or torque seemed to be a less difficult way to go for the average guy installing it in his garage.
| Arlen Ness Cheap Shot |
Dobeck (Techclusion) TFI Controller |
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For this project we choose the Arlen Ness Cheap Shot, manual pot adjusting unit. It was $250 and easy to install. I’m pretty sure it’s the Dobeck Performance unit, that is being sold by Ness. Either way, Ness or Dobeck Performance , it’s a nice product that’s easy to install and not too expensive. The Cheap Shot has six wires coming off it, power, ground and four leads to the injector wires.
Brake light hotwire / to the Cheap shot power lead
Both Ness and Dobeck have great instructions provided, and Dobeck has a web site with schematics and instructions for wiring all models of Harley’s (www.techclusion.com). Dobeck also makes EFI units for metric bikes too. We decided to install the Cheap Shot on one of my friends (Jeff Reno) bike, a ’99 Road King.
Installation was pretty straight forward, power supplied by the brake light wire, ground to the battery and then we had to find the two wires to the injectors, yellow/white and gray/green.
(Injector wires pulled from harness and spliced into. Injector wires are yellow/white , gray/green)
We sliced in to the main wire harness under the right side plate off the ECU main harness. Using tap connectors provided, connect the Cheap Shot yellow & yellow/white to the injector yellow white. Then connect the Cheap Shot gray and green to the injector gray/green.
Ground to battery ground
After that you have to cut the injector wires between the tap connectors, this makes a new electrical path from the ECU through the Cheap Shot then to the injectors.
Tap-on connectors.
With the diagrams provided, set the screw pots as indicated depending on what changes you have made to the engine i.e. stage one etc. You have four small adjusting screws, one for idle, mid range, full throttle and RPM’s.
After a few adjustments and a couple high speed runs, we had Jeff’s bike dialed in. The green LED is the idle adjustment, the yellow is mid range, followed by red for full throttle. the last LED is for RPM, which is factory set, but you can still adjust it if your bike has more than the 4500-5000 RPM capability. It took about 30 minutes, and runs like a scolded dog! Plus, if he decides to make more modifications to the engine, he can adjust the Cheap Shot accordingly. Dobeck (Techclusion) and Arlen Ness offer fuel tuners with direct hook up to your fuel injectors, which makes it a no brainer as far as installation. Dobeck still offers the inline splice unit for those of you who do not want to mess with the injectors, and I found the Cheap Shot in the Bikers Choice catalog. Just recently Cobra came out with a new product, the Fi2000R Powerpro Tuner Digital Processor.
The Fi2000R has no adjustments, no PC downloads, and makes up to 80 EFI changes a second, you simply plug it in. I deem this to be state of the art, and plan to install one on my bike very soon. stay tuned for the Cobra Fi2000R install, I think you’ll like it.
All the schematics and instructions come with the product, and you can view a cool installation video at www.techclusion.com along with schematics for every Harley made.
Tail gunner out, until next time.
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