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Introduction
I originally put this page together to document my own attempt to convert my 1978 z1000A2 to EFI using a Megasquirt EFI unit that I had built by hand. With so many project bikes on the go in the last 2 years the EFI project has been sidelined while I get bikes on the road and restored. During that time my friend Dave Sloan converted his z650 to EFI and both our knowledge on EFI has been greatly enhanced as a result. In recent times I have collected 4 bikes with EFI, a 1980 z1000G, a 1981 GPz1100B1 and 2 1983 ZX1100-A1's all fitted with working factory EFI but the early system used in 1980 and 1981 differs from the system used from 1982 till 1988.
Early Kawasaki EFI Systems
The first Kawasaki EFI design was released in 1980 and was based on a system similar to an L-Jetronic system from Bosch. It used a Volumetric Air Flow (VAF) sensor, to determine airflow as most car EFI systems used at the time. This system was introduced on the z1000G and H models of 1980 and continued on the GPz1100B1 released in 1981. Ultimately the first generation system proved to be unsuitable for motorcycles due to wide fluctuations in the air flow in the inlet tract when the throttle was opened quickly, the air flap design was proven to be unresponsive and unreliable so in 1982 a new system based on the Alpha-N algorithm was supplied by Hitatchi for the GPz1100B2 models and remained in use till 1988 on a number of models.
Later Model (Alpha-N) EFI System
From 1982, the Hitachi EFI system was used on all EFI models. The alpha-N system required a real TPS that correctly reports the throttle position (the early system was just an on/off switch), it still used both an engine coolant and air temp sensor but the VAF was no longer needed. Inside the microcontroller unit was a MAP sensor to measure air pressure.
My understanding of how it works
From what I have observed, the Hitachi EFI system is pretty simple and mimics what most basic Alpha-N systems do, the Microcontroller (a Hitachi 6801 CPU) calculates fuel requirements based initially on the TPS and engine revs and then uses the MAP and temperature sensors to calculate the finer metering for the given air pressure and the air temperature. The engine temperature sensor is used to determine the enrichment needed when the engine is cold. As the engine heats up less enrichment is used. You can test this by using a variable resistor on the sensor to change its resistance.
The engine revs come from a signal derived from the IC igniter unit that also feeds the ignition coils, the revs and the reading from the TPS are used to cross reference a map table tuned to the engine's volumetric efficiency (VE), the map table tells the system how much fuel to initially use, the air temp and MAP sensor feed into the algorithm so that the correct fuel metering is produced for the (Air Fuel Ratio) AFR required.
The injectors are "bank" fired, (that is they all fire at once). The injectors have a low resistance so that they can snap in faster at higher RPM, Bosch may have supplied them as an OEM. High impedance injectors will not open and close fast enough at high RPM so they are not suitable replacements. If a problem in the ECU occurs, it flashes a coded sequence using a diagnostic light on the controller case and flashes the red "general warning" light on the dash to indicate a problem.
When you turn on the ignition, and the kill switch is "on", the fuel pump will prime the fuel line for around 2 seconds. If you need to test the fuel pump, you can, on the zx1100A1 models onwards, remove the black relay and short two of the pins to cause the pump to run continuously for testing purposes. Once the engine is running the pump runs continuously. Despite its size, the pump is one of the best designed with a low current draw, so it is worth keeping (replacements cost $300 or so).
The fuel pressure is regulated by vacuum pressure, If the throttle is opened the vacuum drops and the fuel is restricted from returning to the tank as the injectors will now require more pressure as they are pulsed open more to allow more fuel to enter the inlet manifold.
Pretty basic!
The images above are a TBI assembly from a GPz1100B2, mounted on the end is the TPS at the top is the fuel rail and each injector is directly connected to the fuel rail. In the top picture is the fuel line pressure regulator. It is vacuum powered so it is connected to two of the inlet manifolds (it does not matter if it is connected to 1&4 or 2&3).
Diagnosing EFI Failures
The Alpha-N EFI system used between 1982 and 1988 includes a diagnostic feature to enable faults to be determined and rectified quickly. Mounted on the Microcontroller unit is a light that flashes an error code using long and short flashes. To represent "13", the unit will flash a single long flash, followed by three short flashes, the delay and repeat until the issue is corrected or the power removed.
Below are the codes:
11 TPS is either shorted or open circuit.
12 Air Temp Sensor is open circuit or shorted.
13 Engine Temperature Sensor is open circuit or shorted.
21 MAP sensor is faulty
22 starter switch detect is fault.
23 Ignition pulse missing
31 Memory or CPU is experiencing failure.
The early system used on the 1980 z1000G/H and 1981 GPz1100B1 models has no ability to provide diagnostic information as it is an analogue system and all I can say is replace it with the later model system or convert to a new EFI system like the Megasquirt.
The most common failures on the early Kawasaki EFI system are generally electrical connectors and possibly faulty sensors. Fortunately the sensors are easy to measure and faults with them can be diagnosed if a logical approach is used. Check for damaged wiring also as open circuit sensors will trigger a diagnostic code.
Sensor Characteristics
The engine temp sensor changes resistance as the temperature changes, the hotter it gets the less resistance it has.
30(C) 1k4 - 2k2
20(C) 2k0 - 3k0
0(C) 4.7k - 7k6
The TPS is conceptually like a volume control, it is linear from full clockwise to full counter clockwise, the TPS has 3 signal lines, one is the signal line that varies between the end points of 0 and full voltage.
The ignition pulse line is a 12V line that drops to zero at ignition firing point.
This is the right hand side throttle body unit to which the TPS is mounted to. The unit has been vapour blasted by Specialised Blasting Services. At the very bottom is the mounting holes and there are two threaded holes at the top.
Installation Issues
The installation and setup of the physical components for EFI are pretty straight forward. If you use the Megasquirt then you can buy or build a harness, if you buy a Microsquirt you get a harness with it. Then you need to mount the fuel pump and connect it's power supply to an automotive relay so its powered directly from the battery and not via the ignition switch. Fuel pumps in later model motorcycles are "in tank" types while the first generation are externally mounted.
The fuel pressure regulator shown in the above photos is required to ensure that there is sufficient fuel when the injectors open, the excess needs to flow back into tank so the bottom of the tank usually has a one-way valve, if you don't have one you need to obtain one and fit it in a way that it does not leak.
EFI Components
The following are the minimum components needed to install an EFI system:
Throttle Body assembly with suitably sized Injectors. (known as TBI).
Throttle Position Sensor (TPS) mounted onto end of TBI assembly.
MAP sensor typically 1 bar for normally aspirated engines.
Inlet Air Temporature (IAT) Sensor.
Coolant (CLT) Sensor.
Fuel Pump.
Fuel Pressure Regulator.
Standard automotive relays for pump and EFI unit.
Electronic Control Unit (ECU also known by a number of acronyms).
The following components are what I have or intend to use for my EFI conversion:
GPz1100B2 TBI (could also use GSX or any modern (TBI) components
GM 1 bar MAP sensor from a VN or later Commodore (standard GM sensor)
GM Inlet Air Temporature (IAT) Sensor
GM Coolant (CLT) Sensor
Original Kawasaki External Fuel Pump
Standard Kawasaki Fuel Pressure Regulator
Standard automotive relays for pump and EFI unit
Additional fuse box for new components
John Robinson has also produced an excellent book on the chassis components. here is a link to it. I don't own it, but I have friends who recommend it.
Very useful information on throttle bodies for a range of vehicles can be found here:
If you are after an excellent guide to EFI, this book by my friend Adam Wade is worth obtaining. It covers the technology and the systems used on a variety of motorcycles. It has been criticized for not having any useful information on Megasquirt but for what it covers its excellent. As EFI is now being used on more and more motorcycles the book will in time go to second edition with information on a range of after market systems as well covering the Mega and Microsquirts (Adam.. that's a hint ;)
Finding quality information on the theory of motorcycle engineering is tough in the world of the internet. This book contains well researched (and useful) theory on engine design and inner workings. I have it and reference it often as a resource when writing. If your into two strokes there is an edition covering that topic.
The connector is numbered left to right with pin #1 on the lower row of pins with #12 above #1 . Pin-out and wire colors that are viewed from the wiring harness:
#1 Black/Yellow Ground
#2 Blank
#3 Blank
#4 White/Red Battery +
#5 Blue/Red Sensor Ground
#6 Blue Air Temperature Sensor +
#7 Blue/Yellow Control Unit +
#8 Green Engine Speed
#9 Blank
#10 Gray Engine Temperature +
#11 Blue/White Throttle Opening Angle
#12 Yellow Injector Drive Signal
#13 Blank
#14 Blank
#15 Blank
#16 Black/Green Control Unit Ground
#17 Blue/Orange Throttle Sensor +
#18 Black Engine Speed
#19 Red/Black Starter Signal
#20 Blank
#21 Green/White Fuel Pump Relay Drive Signal
