MicroSquirt.com read only forum (Jan.15,2018)

Help please, Im banging my head off the wall trying to resolve a spark problem on my Honda CB500 180 deg twin cylinder motor cycle. I was running fuel only but now im taking over the ignition.. or would like to..

Microsquirt V2 using B&G 2.890

Im using a 12-1 crank wheel with VR sensor and a MRE sensor (works like a VR sensor but kicks out a square wave like a hall sensor) triggering off the camshaft, the sparks are provided by a pair of igniter coils. The problem im having whilst trying to set up "dual spark" is that both sparks appear (I strobed both sides) to be happening at the same time.. ???

Here is my current set up.

base ign..

trigger offset = 15
skip pulses = 1
predictor = last interval
time mask = 0.5
% mask = 35

cranking % = 75
after start % = 50
norm run % = 25

input capture = falling edge
cranking trigger = trigger rise
coil charge = standard
spark output = going high

advanced ign

trigger wheel teeth = 12
missing teeth =1
skip teeth = 12 ( tried 6 but it over fuels (wasted spark ?))
delay teeth = 10

dual spark options = falling cam sync with tach or wheel
off set advance = -180 ( have tried zero and +180 but same effect)

please help, if I had any hair left id be pulling it out

You are probably not going to get much help unless you post a msq and a data log.
But right off the bat, you have to set the skip teeth to six six or it is only going to fire once per revolution.
Have you checked tour timing with a timing light?
What tooth is your crank sensor on at TDC?
Where is your cam signal in relation to the crank wheel.Is it like this?

c. M-N toothed wheel on input 1. The cam synch on input 2 must be placed so that it occurs during the missing teeth. Ignition starts on the tooth after the missing tooth. If a cam synch has occurred just before this tooth, it fires on Output 1, otherwise it starts with Output 2. Thereafter the outputs alternate. This setup provides the fastest startup because you don't have to wait for cam synch. Note that the cam detection polarity (aka. "input edge capture") is independent of the crank detection polarity, and you must specify both.

For this option there can be no trigger return and no EDIS. Also, note that while having both a crank and cam signal gives us the information we need to control one coil per cylinder (COP), and sequential fuel injection, we only have 2 ignition outputs (and 2 injector outputs) so this is not possible with more than 2 cylinders on MicroSquirt® controllers.


M, the total number of teeth, must be such that MegaSquirt-II will be able to 'skip' a certain number of teeth so the only the right number of teeth are counted as 'tach signals' per revolution. In general, this is:

4-strokes: skip_teeth = (2 × M) / #cylinders
2-strokes: skip_teeth = (M) / #cylinders

Alternatively, the total number of teeth must be a multiple of one half the number of cylinders for a 4 stroke (a multiple of the number of cylinders for a two stroke).

Thanks for the quick reply.. I have altered some settings (skip 6 to get a 180deg offset spark)

msq and a data log attatched

Ignition timing double checked with a timing light.

timing jumps to 180 deg out during some of the cranking attempts.

Cam trigger set up as per trigger wheel page.

For this datalog the ignition was powerd by one battery and the starter motor was driven by another.

Looked at your msq. You have your offset for output 2 set to 0, it should be 180.
Time mask should be 0.2 and percent 10.
Are you sure your cam sync is triggering on the missing tooth?
Have you tried it with no cam sync, just single crank wheel wasted spark?
I don't know why you are running cam sync,unless you feel you need sequential injection?
For some reason in your log the battery voltage doesn't seem to be that steady.
What kind of coils and ignitors are you using?
If it was me I would update the firmware to 3.78 and use the auto trigger setup. This almost makes the toothed wheel setup foolproof.
http://www.megamanual.com/files/code/
http://www.megamanual.com/seq/autotrig.htm