Name: Steve Oxley
Vehicle: 1985 Honda CBX750
Engine: 750cc, inline 4, naturally aspirated
Injection: Port, using throttle bodies and injectors from a 2003(?) Suzuki GSX-R600
MegaSquirt: Original v1.01 unit from the very first Bruce & Al group buy, way back in 2001 / 2002. The firmware has been updated to B&G 3.000. No other changes have been made to the unit.
Description: The CBX is the non-American version of the CB700SC 'Nighthawk'. It's 50cc larger, and with a chain drive instead of the Hawk's shaft drive.
Fuel pump is a Suzuki 2002 GSX-R 750 unit, providing whatever pressure it's set for. I've seen them rated as both 40psi and 43.5psi units. I modified the position of the fuel level sender, so that it would give a signal at a useful fuel level, rather than coming on when the tank was still half full.
ReqFuel is set to 5.6 msec, two banks of two injectors, alternating. It's set to fire injectors 1&3 and 2&4 in pairs.
There is no coolant sensor - the CBX is oil cooled, and I found it easier to rig a switch to the console that connects two resisitors to the MS - one for a 'hot' position (93 degrees C) and one for 'cold' (-15 degrees C).
Website: http://www.teamrc17.net/tech/projects/EFI/EFI.html
I played with using Speed-Density for the control algorithm, but gave up as I could not get a useful vacuum signal. As soon as I switched to Alpha-N, the bike ran much better right away, even with a fuel map that was more guess work than calculations.
Update: March 15 2006: I spent a couple of hours putting the bike through it's paces on a dyno this morning. At the end of it, I have a fuel map that looks really strange, but the bike runs better than it ever has.
We didn't do a dyno run (and I wish we had done a 'before' and 'after' for comparison!) but the bike runs a lot smoother and pulls a lot harder now than it ever did. About all I have to do now is balance the butterfly valves in the throttle bodies, and I'll be set.