PFI - Performance FI

Buy Now

EZ's Story


My name is E.Z.(really, my initials). The photo is current, having been taken early in October. That's me, on my scoot. Built ten years ago around a 96" S&S package, with a Mikuni carb, roller rockers, enclosed belt drive, RC wheels, rotors, pulley, WP inverted fork, PM forward controls, Kraft Tech frame and on & on.

After it hit the road the bike was put on the dyno. At 2200 rpm torque came on big & climbed strongly until 3500 rpm, where it measured 106.7 ft.lbs. Rear wheel horsepower was 90.8. Nothing to make my hair stand on end, but not a slug either !

The bike remained the same for all those years, that is until a couple of weeks before this photo. That's when I made a change. I knew that there'd be some change, but I was "blown away" by just how, a lot !!

What I did was simply put an entirely new fuel system on my bike. In a single afternoon I removed the Mikuni manifold & carburetor...then I installed what turned out to be the biggest single improvement to my motorcycle's performance...fuel injection. That's correct, not regular fuel injection but "PERFORMANCE FUEL INJECTION".

Listen, I wasn't born yesterday. I have a '46 Knuck w/sidecar, nearly bone stock. It, of course, is equipped with a Linkert carb. I have cages too, a '71 El Camino with a big 4-barrel Edelbrock carburetor, a late '73 Porsche 911 Targa with Porsche's first CIS injection system and, finally, a late model injected Chevy Suburban.

Knowing how well the fuel injected vehicles perform, always & without fail, I often wondered why it seemed so difficult to adapt injection to the V-Twin style mill. In fact, this particular story began over 16 years ago. That's when my bro, Mil, and I met Stewart Prince. Stu was employed at a university in their engineering dept., and was particularly interested in fuel injection. Having successfully introduced some special applications, he was eager to make somethin' happen with these V-Twin types.

What we all wanted was "useable power", more power to the ground at lower rpm's. Grab a handful & go, right now, anytime & anywhere !

Well, things progressed slowly, in part due to the motor's distinctive firing pulse as well as some other quirks.The early days led them out of the nineties and into the new millenium. You see, they envisioned an injection system that was totally self-contained, relying on nothing done to date, one that could do whatever the accepted systems did, yet a fuel injection system that was so bold & so unique... a system that allowed you, the rider, the opportunity to "fine tune" that big, powerful engine with "one fuckin' finger" ...yes, I'm speakin" about your finger, the one you use on a personal computer.

Man, you can plug into this bitch & really talk to it. Trust me when I say r-e-a-l-l-y talk to it & if you don't like any part of what you're finger has done, simply don't save the new map & revert back to the original one you worked off of. From fuel enrichment, fuel pump parameters, injector timing, the ignition map, rear cylinder trim, warm-up diagnostics, etc. it's all there. In fact there are 256 points of speed & throttle position capabilities offered. Use some or none, that's the beauty because when you receive this system it'll already have the map best-suited for your ride installed ! Should you want to "tweek-it" further, go for it!

No shit, this bike came alive. I can tell you that fuel delivery was instantaneous.

No 1-Mississippi, 2-Mississippi & so on, I mean right now ! It pulled hard, real hard.

My recommendation: start squeezin' that rubber ball in your spare time !

Power is there when you want it, but amazingly with better fuel mileage and at lower operating temperatures. My first ride of any substance was about 95 miles, nearly all freeway. I went at 6:30 in the morning, 80-90 mph, no less. Returned mid-afternoon in 87 degree temperature, after running 85-95 mph. Motor performed flawlessly, fuel economy calculated out to 45 mpg and my oil temperature was 210 degrees Fahrenheit !!!!

The system only uses two sensors, engine rpm & throttle position. The throttle position sensor is mounted on the throttle body & measures the butterfly angle. The rpm sensor uses a stock ignition pick-up, but the small wheel behind it has been replaced with their "special wheel", one having six teeth with a long slot between tooth six and tooth one. It's the next tooth after the big tooth that tells the brain where top dead center of cylinder # 1 is. It's real important, since the brain must know where this point is to perform sequential fuel injection & single fire ignition.

The brain then uses the sensor information to determine how much fuel & ignition timing to output to the engine. There's a knob on top of the brain that adjusts fuel mixture and also serves as a choke. Beside it are two LEDs that turn red & green. red means the brain is on, green means the ignition pick-up sensor has detected a tooth on the wheel.

The brain controls the injectors, coils & the fuel pump. After turning on the main ignition switch, the brain turns on too. It starts off by activating the fuel pump for approx,. 4 sec., then turns it off until the engine starts. It then sits & waits for inputs from you. If you turn the throttle, it thinks you want to prime the engine before starting and inject fuel. Pressing the starter button will turn the engine over as well as the pick-up wheel. After a couple of revs, the brain will detect the first tooth on the special wheel & "synchronize" the system. Then & only then will the injection system start the engine. It's then that the brain injects fuel and fires the coil(s) based on the engine position determined from the pick up wheel's teeth...this is the key to how such accurate control over the engine takes place !

Again, this system delivers....more torque over the entire rpm range, better fuel economy & all this at lower operating temperatures !!! Shit, what else do you want ? Maybe one thing...a better, badder clutch set-up. PERFOMANCE FUEL INJECTION will likely drive right thru your existing clutch assembly. Be prepared. Shit, I didn't care. What's a few more bucks when you get the enormous rewards that this set-up brings with it !

In fact, how much fuckin' bread have you dropped over the years to get a little bit more, and sometimes nothing at all ??????

Once again, I wrote this blog(?) because it just happens to be the only other product besides my ol 'lady of 30+ years that did a fuckin' bunch more than expected! (And, I felt it was worth sharin' with ya)


Sign up for our Email Newsletter

Read About Other Harley Riders' Experience with the Pegasus System

Check out this review of the Pegasus system by Easyriders Magazine

(Special thanks to Joe Teresi and Cathy Gibson at Paisano Publishing for providing a copy of this article. Note: this file is approximately 53MB and may take longer to download)