Motorcycle History: 33 Years Of Motorcycle Fuel-Injection

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Motorcycle Fuel Injection

Each week RideApart looks back to highlight key milestones in motorcycle history from innovations to significant model introductions to racing successes and, of course, some of the disastrous things we’d rather forget. This week it’s Kawasaki’s introduction of the first motorcycle fuel-injection system.

In the late 1970’s Kawasaki Z1000G-1 Classic was a popular heavy cruiser, weighing in at 555 lbs, with a claimed top speed of 127 mph, and 93 hp at 8,000 rpm from its four-stroke, transverse four-cylinder engine. But the Kawasaki engineers had also done something to it that was regarded by customers and the media alike as really rather odd.

1980 Kawasaki Z1000 Classic
1980 Kawasaki Z1000 Classic

For the 1980 model year the Z1000 Classic was equipped with an electronic fuel-injection system (pictured above) pushing its retail price up to $4199, which was $500 more than the standard carbureted Z1000 LTD version. That was a whopping price difference back then even though the Z1000 Classic’s fuel-injection system was presented as the very latest engineering technology available on a motorcycle. You even got a computer of sorts stashed under the seat and the chance to ditch an engine’s choke for cold starts once and for all.

The specialist motorcycle media at the time was immediately skeptical about this new development with one publication even stating that fuel-injection on a motorcycle was “the death knell for home maintenance and road side repairs”. The journalists were also somewhat baffled by the Z1000’s onboard computer, which regulated the fuel-injection, describing how it worked as staggeringly complex.

The fuel-injection system on the Z1000 Classic weighed 16.7 lbs rather than the 15.7 lbs of a conventional carburetor assembly on the Z1000 LTD. It was manufactured for Kawasaki by Japan Precision Electronics, which had the rights to produce the Bosch Jetronic system specifically for motorcycles. In actual fact it was identical in concept and design to Bosch fuel-injection that was being used on Datsun (Nissan) cars at the time.

How that early system on the Z1000 worked was to monitor via a series of sensors, ambient air temperature, engine temperature at the cylinder head, airflow into the airbox, engine revs, throttle position and intake manifold vacuum.

At the Z1000’s introduction by all accounts it did its job well with Cycle World’s 1980 review of the Classic stating:

“Considered in terms of function alone setting aside the real-world factors of cost and ease of maintenance or repair, the Kawasaki fuel-injection system works flawlessly.

“Let the engine idle down to 1000 rpm in fifth gear, then grab a handful of throttle. Instead of a gasp and a dead engine, the rider gets a smooth, steady acceleration without a shudder of complaint. The engine can’t be killed with the twist grip, can’t be handled so clumsily that it won’t run any way but smoothly and steadily.”

The really curious thing in all of this was at the launch of the EFI Z1000, Kawasaki remained remarkably coy about why it had launched fuel-injection on a motorcycle in the first place. Its fastest bike in 1980, the KZ1000 MkII, was equipped with carburetors and cost $750 less than the newly fuel-injected cruiser Z1000.

The truth of the matter lay with the Environmental Protection Agency here in the U.S., which was starting to tighten emission regulations on all road vehicles.

In 1980, Kawasaki was the first motorcycle manufacturer to recognize that in the following years, bikes would have to meet even tougher compliance laws. Fuel-injection, rather than carburetion, on an engine would be one way to get a motorcycle through emission testing.

So it was a 1980’s Kawasaki heavy weight cruiser that was the start of what we have all come to accept as entirely normal on today’s motorcycles – fuel-injected engines.

We’ve never ridden a Z1000 but we have heard that in later years they are really difficult to work on, have a tendency to be unreliable and parts for the fuel injection system are nearly impossible to find. If you own one, or have owned one, what’s been your experience?

Related Links:
Motorcycle History: 25 Years Ago Today – BMW First to Offer Antilock Brake System
Motorcycle History: 50 Years of Full-Face Motorcycle Crash Helmets
Motorcycle History: 26 Years Ago Today – Radial Motorcycle Tires

  • Piglet2010

    Yet we still have carburetors on 2014 model year bikes such as the Suzuki DR-Z400SM, which for this class of bike is enough to make me wait for something better.

    • Brett Lewis

      When I was into the DRZ’s (S and SM), I actually had a lot of fun with the carb-swapping, jetting, air-box mods, and exhaust upgrades. I learned a lot and spent a fair amount of time and money on the bikes, but after all that – yeah, fuel injection would have been better. Power Commander and exhaust and done, if and when that was “needed”.

  • ThinkingInImages

    Great article, Tim. I thought it was the CX500 Turbo, but this predates that. It must have been interesting to work on and repair.

    It’s interesting that FI has been around for more than a quarter of a century on motorcycles and there’s still resistance to this “new” technology. I wouldn’t buy a motorcycle without it these days. It makes the entire start-up process less of a process.

    • Piglet2010

      While a bike that will not run when cold at less than 5000 rpm is annoying (e.g. pre-gen Ninjette), the best part of electronic fuel injection is that the bike gets a de facto tune-up several times per second.

      • ThinkingInImages

        True enough. A quick hit of the starter and I’m good to go seconds later. It’s brilliant.

        In the “old days”, you had to open the petcock, pull the choke, hit the starter or kickstart, pray it fired, push down the choke some so you didn’t foul the plugs, and maybe ride away carefully without stalling. After a bit you had to remember to push the choke down/off.

        What “fun”.

        • E Brown

          The old days? I do all that weekly, on my CB400T! :)
          Really not that bad – typically while the bike is warming up I zip up my jacket, put on my helmet, put on my gloves, stow anything I’m carrying, then start off. On my CBR600R, the only difference is the bike’s off while I do all that.

          • Piglet2010

            My CB400T never had any issues with running properly while cold (neither does my current TW200), unlike my Ninjette that dies on even half-choke and then does not want to restart.

            • Mark D

              Those ninjas are notoriously cold-blooded. If you haven’t yet, pull the carbs and drill out the pilot jet adjustment screw, and turn it out about a turn, or a turn and a half. They were turned super lean from the factory to pass CARB standards.

              • Don Fraser

                you don’t have to pull the carbs, drill through the side , just above the block off plug and pry it out, then do an idle drop to set the fuel screws, still a little funky just off idle, but way better than stock

        • Jonathan Berndt

          hmm, you should still let it warm up a bit, metal is still metal.

          • Piglet2010

            I ride almost right away, but keep it at part throttle and low revs until the temperature gauge (on the water cooled bikes) gets into the normal operating range.

  • Aaron Kirkland

    I’ve been riding both. I had an ’09 Sportster with fuel injection, and I learned a lot. Even wrote out an ignition curve converter because the guys with carbureted models had ignition curves based on inHg and the FI guys had them in KPa. Never really had an issue with it, though… I think it worked well.

    I then had an ’08 KTM 690 SMC, which had by some accounts the most finicky EFI system with it’s hybrid manual/fly-by-wire throttle control. I somewhat disabled that system through TuneECU, and the bike was amazing. Used a G2 cam to avoid the herky-jerky throttle.

    Now I’m back to my old 1987 Honda XL600R. Carbureted, but probably one of the trickiest systems of the 80′s/90′s with it’s dual, stepped carburetor setup. But I like it, and when setup properly, it works great. I’ve got it dialed in for one-kick starts, hot or cold.

    I think you get to know your machine better with carburetion.

  • Carlos O

    Im the proudly owner of a kz1000-G Classic with a working EFI. You should be careful and keep your battery well charged to avoid any electronic problem. That early EFI is very similar as a Mikuni carb. You must have it warmed so It wont rev, you must sync the injectors as you sync carbs, you can also set the idle revs by turning a screw. Of course you cant expect to remap the EFI, so big changes such as a performance exhaust or pod style air filters, even a change of city will really mess with the range of rev, oxygen, etc

    Really a fun bike to ride time to time not really a daily driver.

    I do the same maintenance in my carb and EFI bike, the troubleshooting is almost the the same and if I fry some electronics not even a modern dealer will go inside the circuitry to fix it, they will change the sensor/computer. Some HP loose yeah… some MPG won, yeah… sun shines for everybody.

    • Carlos O

      Worth mentioning that the production of this bike was just 1 year with nearly 3000 units shipped. Many of those had the EFI fried by the first 10 years and replaced with the carbs from the MKII. Wonder how many are still have a working EFI

      • Tim Watson

        Thanks for taking the time to tell us about your bike. Good to hear they’re still out there and running!

  • KeithB

    I have had plenty of carb bikes and recently got an injected FJR1300.
    Installed a Power Commander module that allows “off stock” fuel mapping.
    Wayyyyyyy better than repeatedly pulling carbs and tweaking jets!
    Had no idea FI was introduced to bikes that long ago.

  • Aakash

    While I appreciate the many positive benefits of EFI, I love the linear, analog feel of a well-tuned carburetors…that is, until the temperature changes 5-degrees, I change 1000 feet in elevation, it starts raining, the sun goes away or I have entered a magnetic hot-spot; then it’s time to rejet.