Homebrew EFI for Motorcycles

I've never really liked carburettors -- too many airways, too many little brass widgets, not enough adjustability -- and so I'm interested in experimenting with retrofitting EFI to my bikes, and making it more fault tolerant and more easily diagnosable than the original carbs.

My aged Honda XLV750R has chronic carb problems, so it gets to be the guinea pig. These pages attempt to chronicle this foolhardy adventure ...

Subsystems

Throttle Bodies

• Fitting to the XLV.
• TPS
• Injectors

Fuel Plumbing

• GPz Plumbing Parts
• Low Pressure Fuel - from tank to fuel pump, and from regulator to tank, including a low-pressure filter.
• High Pressure Fuel - from fuel pump to injectors and fuel regulator
• Manifold Air Pressure - to fuel regulator and to MAP sensor.

Sensors

• Crank Angle / Tach: The XLV has a pair of Variable Reluctance sensors mounted on its crank, each fires at TDC for its cylinder.
• TPS: See 'Throttle Bodies', above.
• O2/Lambda Sensor: 4-wire heated, Mounted in exhaust pipe, back behind the join. Wide-band sensors are becoming quite common these days, but I'll probably try to get it working with a narrowband first.
• Manifold Air Pressure (MAP): May or may not be necessary, depending on the algorithm used. May or may not be sufficient, as there isn't a lot of air volume between throttle and inlets so I'd expect the air pressure to be very erratic.
• Manifold Air Temperature (MAT): Mounted in the plastic airbox lid, I think. Possibly mounted so that the entire sensor is inside the airbox to make sure it reads the correct temperature. See also this page on MAT Sensor Location
• Cylinder Head Temperature (CHT): The XLV is air/oil cooled, so it's tricky to measure the engine temperature. Probably the simplest way is to tap a temp sensor into the rear head cover. This would provide cold-start enrichment info to the ECU, and also enable me to keep an eye on the state of the cooling system.

ECU Hardware

• Initial Thoughts on ECU
• Initial Thoughts on Ignition

• Enclosure / Connectors
• Inputs
  • O2 sensor - amplifier
  • MAP sensor - 0 .. 5 V
  • TPS - 0 .. 5 V
  • Other (switches and stuff)
• Drivers
  • Injectors - Optoisolated MOSFET
  • Power - for fuel pump, O2 sensor, starter.
  • Display - (leds and stuff)
• Power
• CPU

Links