Motorcycle Ignition Output

[Paul_H]

I am in the process of planning my installation of Microsquirt to manage fuel and ignition on a Ducati V-Twin motorcycle engine. My current ignition setup on this engine is Lucas Rita electronic with two Pazon dual output 2.2 ohm 6 volt coils connected in series firing two plugs per cylinder. Each coil fires accross two cytlinders (wasted spark) and this setup works very well. With Microsquirt I will be using dual tach inputs and initially planned to duplicate this coil setup (dedicate one per cylinder) so I could direct drive each one with the two ignition outputs as I believe this would be optimum although I would be wasting one output on each coil to ground. Alternatively I could stick with the current setup, providing that I could tie the ignition outputs from Microsquirt together without adversely affecting the VB921 coil drivers. After all of this I guess my question is, is this possible?

regards
Paul

[SQLGUY]

I also don't see why you would need to. If the coils are currenty run in series with a single driver, you should be able to do the same with uS, running the two coils in series off of one ignition output. In fact, seeing as their 6V coils and uS is mostly setup for 12V components, series setup may be required if you don't want to replace the coils or use resistors in series with them. I assume, since their in series, that the rest of your electrical system does run on 12V?

[Paul_H]

Yes it is a 12volt electrical system. The existing ignition system uses a single VR sensor triggered by a two tooth reluctor on the rear cylinder camshaft. This sets up the phasing for the odd angle but it seems that this is not a configuration that is compatible with dual spark in Microsquirt and anyway I still need a crank tach input for RPM. So I chose to install two VR sensors at the appropriate spacing on the crankshaft triggered by a single tooth wheel to achieve firing at the odd angle of the Ducati engine.

[SQLGUY]

I think the easiest thing may be to run the coils independently through Microsquirt's two ignition channels, and use 2.5 Ohm power resistors (2 to 5 Watts) in series with each of them.

[honda33cr]

Paul,

I think that your stock setup should work just fine with microsquirt. I am doing the same thing that you are except that I do not have a dual spark engine. Either I am doing things the wrong way or the single vr sensor on cam timing is sufficient enough for uS. If you bring in the vr sensor on the vr input and use single cam wheel under dual spark options you should have no problem with the odd fire engine. I am at the stage where I have a valid engine speed during cranking and I was getting spark but I think that one my coils went bad and fried the ignition driver. If you place about a 15 k resistor inline with the vr+ signal that should help clear up any vr signal issues. I definitely think that your stock set up will work, you just have to decide how you want to wire your coils.

[SQLGUY]

I think I see what you're saying: connect the switched side of the "bottom" coil to both pins 11 and 12 so that one IGBT can fire the coil pair for cylinder one and the other can do it for cylinder two. That does make sense as well, though it might get a bit weird if your #1 and #2 dwell times overlap at higher RPMs.

I still like the resistor idea better since it would avoid any interaction issues and also reduce stress on the coils a bit.

Cheers,
Paul

[newtyres1]

I think I see what you're saying: connect the switched side of the "bottom" coil to both pins 11 and 12 so that one IGBT can fire the coil pair for cylinder one and the other can do it for cylinder two. That does make sense as well, though it might get a bit weird if your #1 and #2 dwell times overlap at higher RPMs.

I don't think the dwell times would overlap, otherwise it would not work correctly straight from the factory. 4.4 ohms and 12V across the 2 coils in series is an easy load for the uS. The main question is can the two independent ignition outputs be tied to the one coil? I would think so, but hopefully someone with more authority will chime in.

It never ceases to amaze me the plethora of different ignition setups on different bikes/cars/IC engines in general

Ian.

[Bruce Bowling]

It never ceases to amaze me the plethora of different ignition setups on different bikes/cars/IC engines in general

Ian.

Me either

You can probably get this to work, but you may also look at using something like a LSx-style coil on this setup - these are inexpensive and will work for sure...

- Bruce