Homebrew EFI for Motorcycles
This project has more or less stalled for the moment: the
XLV is off the road, and the BMW is keeping me busy enough
for the moment! I've been helping out a little with
EFI RC17 (CBX750) in the meantime.
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 ...
I sourced a set of 4 GPz1100-B2 34mm throttle bodies from a local
wrecker's yard, along with their fuel pump, fuel regulator
and TPS. They're not a perfect fit for the application, but
they're not bad.
EFI systems need an awful lot of spaghetti ...
- Crank Angle / Tach: The XLV has a pair of
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
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.
- Enclosure / Connectors
- O2 sensor - amplifier
- MAP sensor - 0 .. 5 V
- TPS - 0 .. 5 V
- Other (switches and stuff)
- Injectors - Optoisolated MOSFET
- Power - for fuel pump, O2 sensor, starter.
- Display - (leds and stuff)
See the Homebrew EFI links page.
homepage / motorcycles