2 squirts/cycle with 3 cylinders?

[wmax351]

I'm currently running my BMW k75 motorcycle with 2 squirts/cycle, basically making it think the bike is a 2 cylinder (I'm running fuel only, triggered from one of the wasted spark coils). The OEM Bosch ran 2 squirts like this too, and it runs well, it averages the fuel injected over the cycle, which is better for low RPM and takeoff. I would like to preserve this when I convert it to fuel/spark control. It seems it would be useful to allow this configuration for odd cylinder engines, like 3 or 5 cylinders. I tried running it as a 6 cylinder, but it wouldn't read the RPM right even with wasted-COP mode.

[dontz125]

What sort of trigger wheel do you have? You could run sequential.

[wmax351]

Currently, just doing coil negative trigger. I'll be putting in a crank mount missing tooth wheel. I could do semi-sequential with that, but I would have to add another injector driver.

[dontz125]

You have a triple running as a coil -ve twin?! That must do strange things to the rpm reading ...

You might take a look at the jbperf 4 channel injection and ignition board.

[racingmini_mtl]

Actually, with an odd number of cylinders you can't do semi-sequential with a crank-only signal.

And you can't do 2 squirts/cycle because you have 3 trigger events per cycle. So you would have to fire an injector once per 1.5 trigger event which is obviously not possible. You can use 1 or 3 squirts/cycle.

Jean

[wmax351]

You have a triple running as a coil -ve twin?! That must do strange things to the rpm reading ...

You might take a look at the jbperf 4 channel injection and ignition board.

It's dead accurate. It's a 3-coil wasted spark system. The MS gets the expected number of pulses for a 2 cylinder wasted spark (1 per rotation).

What about running it as a 6 cylinder? It's a symmetrical half of a 6. With wasted spark, it would still be 3 sparks, 1 injection per revolution. I could even do batched sequential like that, batching the "pairs" of cylinders. I would do 3 squirts per rev, but the pulsewidth gets a bit small at idle, and the duty cycle approaches 85-90% at higher RPMs/Loads.