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Kawasaki ZXR750 Introdution
Hello everybody,

at first i just want to introduce me and tell you what led me to this board…

I am an 48 year old german ( located in the area of Frankfurt / Hanau ) motorcycle rider. I worked as mechanic years ago and do all the maintenance on my bikes by myself. All my bikes are Kawasaki ZXR750 from 1993. There is one for street use and one for the track. I want to learn about efi in General.  Therefore i will built a 3rd bike only for the Purpose of implementing injection on an carburated engine. This is no project with a fixed time Frame and the bike will have to be built. The parts are available out of spares for my track bike....

Some Details about the engine:

4 Cylinder Inline ( DOHC. 16 Valve, Liquid cooled )

Displacement:    750ccm ( 45,7 cu in )
Compression:     11,5:1
Firing Order:      1243
Ignition System: transistorized ignition ( wasted spark )
Ignition Timing: 10 Degree BTDC @ 1100 rpm ~ 50 Degree BTDC @ 7000rpm
Crankshaft         VR Sensor ( will add pic of Trigger Wheel later )  *
Camshaft           -
Details about camshaft Timing is available
Transmission Ratios are available
CLT Sensor

* as far as i know the original triggerwheel won`t work well for an efi but i have been told this one should fit plug and play:

4 *38mm CVK Carburators

Also I bought the throttlebody from a different Motocycle which i `d been told should fit. But i am not to happy with the fitment and will take a look for a different one.

Wish List

Wideband O2 Sensor

MAP => can be used to replace CAM Sensor ( ) lowest pressure is Cylinder in working stroke ( I know at least two persons which did this on different motorcycles with MS3E ). One of them told me that he used MAP Sensor wich can read only up to 1bar for better resolution

IndependentThrottleBody ( TPS )
sequentiel Injection ( may be staged Injection )
shift light ( rpm is known , gear ratio also, additional Sensor at Gearbox output ) <= sounds like simple math
flat shifting => beeing able to shift under load without using the clutch
speed limiter <= not important just something "nice to have"
rev limiter
tach out
Data logging => Use of RTC and may be GPS
In a far far future i would like to learn more about the Suspension movements…

High Amp switches eg Fan gas pump and so on

I am able to do the wiring on my bikes but unfortunally i am a noob regarding to electronics. That means that i can solder something to a circuit board but i am unable to find out what is needed to fullfill my ideas bymyself. I hope to improve in that field while doing this conversion.

As far as i understand by now i could have a go with the coolefi Basic board but may have to ask them if they may replace the onboard map sensor with a different type ( MPX4250 1 bar MAP sensor ).

My idea is to start with wasted spark ( and may be injection ) to get the Problem with the missing cam sensor out of the way at the beginning. If that works fine i would try to make use of the MAP pressure Differenz in the different working strokes. But i am aware that i would need a lot of help to get this done. In principle i think it`s about 4 MAP sensors which deliver there data direct to the ems. Then it will be calculated when cylinder number one starts it`s work cycle by having the lowest MAP pressure. This should be possible at low rpm and can be cept up to the higest rpm ( ~ 12000 ) without new calculation as this does not change… If this can be made there is no need for an camshaft sensor and old engines like mine can use full sequientiel injection / ignition.

Now you know about my ideas / dreams and i would be more then happy to hear your recommendations and comments.

Am i at the Right place for this ideas?

Best regards: Klaus

P.S: In the attachment with the ignition curves only the one in the lower Right is for my bike. But it`s a racing ignition. I thought it could be something like a hint...

Attached Files
.pdf   Specs.pdf (Size: 105.99 KB / Downloads: 183)
.jpg   Impulsgeber.jpg (Size: 198.47 KB / Downloads: 210)
.jpg   ZXR-Kurve-Kit-CDI.jpg (Size: 125.7 KB / Downloads: 231)
Hi Klaus!

Cool to see interest in running another bike engine with LibreEMS, we have quite a few under our belt (YouTube for LibreEMS). Based on my experience, I would do the following:

1. Get a high count crank wheel with a missing tooth. Something like a 36-1. Bike motors have super lite rotating assemblies and having decent resolution lets the ECU do more of the work (you dont really have to care about TDC vs nearest input tooth, as long as you know the offset). Those older bikes have low counts and we have broken a couple starters by not adhering to really narrow timing windows, while cranking.

2. Get a cam sync (doesnt need to be exotic, take something from another bike), it will allow you to ditch the wasted spark and time your injections, which is critical for good throttle response.

3. Don't waste your time by not doing the above two things, you will get mediocre results.

Andy should be able to answer any HW questions.
HI Sean,

thanks for your advice. The triggerwheel i mentioned above is something like 22-2. Do you think the resolution is not fine enough?

In regards to the camshaft: I was thinking about having a second VR Sensor above a camshaft. Need to check the valve cover. Unfortunally it`s magnesia. I have to find out how to work on this works best...
Yeah, a 22-2 should be fine. It's the 12/8x crank wheels that can be problematic.
Hi Klaus,

I can answer hardware questions, sorry I'm a few days late in replying.
The CoolEFI Basic ECU can be supplied with a 1 bar or a 2.5 bar MAP sensor on board, they are the surface mount versions of the one you linked.

Photo of Basic ECU with the MAP sensor installed:
Basic ECU with MAP sensor

Let me know if you have any questions.


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