new guy with some questions

[midnight08]

Hello everyone... I am in the beginning stages of my FI conversion on my 1976 CB750.

I am needing to figure out some items pertaining to the ignition pick up on my project. I am running fuel only and my motorcycle runs on a wasted spark system. I am going to be pulling my ignition signal straight from the coils and will be performing this http://www.microsquirt.com/viewtopic.ph ... 86#p151772 to the pick up circuit to try to clean it up.

The only thing that I am trying to figure out is if the wasted spark setting in Tunerstudio is looking for 1 or 2 pulses per cycle. The above circuit will give me 2 pulses per cycle unless i don't tap into one of the coils. If there is a source for me to find detailed information on the features built into Tunerstudio, I would love to find it as i have looked and came up with nothing.

also, I am trying to figure out if it is preferred to run a fast idle valve. or if it is necessary. I am quickly running out of space to hide everything so I am wondering if there are other ways of obtaining the same results. if someone could give me the run down on this or point me in the direction that I can research it myself, I would appreciate it.

[dontz125]

I'm not fully up on 'fuel only' triggering, but I THINK you want 1 pulse per cyl per cycle. Note that a cycle is 720 deg or two revs; the circuit you linked to will (with wasted-spark coils) give 2 pulses per rev or 4 pulses per cycle.

An automated fast idle isn't a bad thing, but isn't really necessary. If you read through the MegaManual and the MicroSquirt manual, you will find a few small solenoid valves that will add extra air. Note also that you could install a needle valve before (or after) the solenoid, in order to help 'dial in' the restriction. A fast-idle valve that is only ever open 5% isn't really controllable; by adding a needle valve the solenoid will have a much greater range of motion and controllability.

[midnight08]

I'm not fully up on 'fuel only' triggering, but I THINK you want 1 pulse per cyl per cycle. Note that a cycle is 720 deg or two revs; the circuit you linked to will (with wasted-spark coils) give 2 pulses per rev or 4 pulses per cycle.

So if I want 1 pulse per cyl, per cycle, then the 4 pulses per cycle that the wiring i posted is what I am after for an inline 4. correct?

[dontz125]

That's my understanding. If you look closely at the graphic, you'll see that the 'coils' are labelled "1&4" and "2&3". Note that with this circuit you do NOT follow the coil -ve procedures of the uS manual, which recommends connecting the OPTO- to +12v; this is to reduce the voltage across the components induced by the coil spike.

With this circuit, there IS no coil spike reaching the uS; the max input voltage is +12v, dropping to 0 whenever a coil fires. If you were to put +12v on the back end, there would never be a voltage differential, and no signal!