Optical sensors and chopper wheel and more

[Norzilla]

Hi

I have started another motorbike project, a custom CBX1000 bored out to 1425cc and a whole lot of other trick bits.( sucker for punishment ) but was talked into using a PowerArc triple spark ignition module to replace the OEM system.

Trouble is that the PowerArc product is total junk and we can't get it to work, in fact ,I was having horrible flash backs to a few years again when first setting up my Microsquirt on the Aprilia V twin Cafe racer and the 3600 rpm VR noise related rev limit etc etc.

Actually it was this that got me thinking again about Mircosquirt and if I could adapt some of the great ideas from the PowerArc system into the MicroSquirt unit and run my bike's ignition on MicroSquirt and leave the rubbish parts of the Power Arc behind.

PowerArc the good Stuff:

1) 3 sparks per cylinder per revolution, between 5-10 deg apart before TDC

2) Anti kick back function: ( this has been a big issue for me and my Aprilia V-twin as kick back on my existing system has broken 3 sprag clutches at a now total cost of repair of about $1000 , pretty aggravated about this)

I now know that the kickback problem is largely due to the B&G Manual recommendation that the sync and first fire be set at the earliest calculatable point to give a fast start up ie within a couple of teeth of first tach sync , it means that if the Battery in not fully charge and the cranking is a little slow on a high comp engine , there is a high chance of kick back, as the beast fires early in the starting cycle and potentially at a point where there is minimal momentum in the system, due to motorcycle's small flywheel and low rotating inertia. ie firing too early in the early cycle stops the piston b4 TDC and hence a kickback and $$$$$$$$$.

The PowerArc methodology is such that the system does not turn the coils on to start charging until 1 full rev has been counted , then the first spark only delivered at the end of the 2 rev , at this point the rotating assembly has gained all the momentum it is going to on crank and hence providing the lowest potential for kickback on the starter sprag.

I believe that the Microsquirt manual should recommend that for motorcycles at least, the system be allowed to count as many teeth as it can, before providing sync and firing the first spark on cranking , it might not be 2 revs as in PowerArc but every bit of delay helps reduce the chance of a kickback and broken sprag clutch.

Or maybe there is a way to set the coil to not be switched on for at least 1 rev then you could leave the sync and fire at the regular earliest opportunity after the 2nd sync and so mimic what powerarc are doing and save the sprag clutches.....

3) I would like to use a optical pick up on the bike and a more accurate timing event ie a binary on or off signal scenario and not a rising or falling signal that is very sensitive to system noise and coil ring and and and and and...


So my questions are

1) I see twin spark is now possible on MicroSquirt V3 but what about 3 sparks?
2) Can the first spark on starting be delayed and how ie what are my options?
3) Can Microsquirt handle an optical trigger sensor or 2 ?
4) Can I use a trigger wheel with 72 slots with the optical sensor?

Thats about it really.... too much to ask??

Thanks in advance to anyone with some ideas on how to achieve my dream....

[24c]

Hi Norzilla, long time no see...

Power_Arc.png (336.43 KiB) Viewed 1213 times

So my questions are
1) I see twin spark is now possible on MicroSquirt V3 but what about 3 sparks?
2) Can the first spark on starting be delayed and how ie what are my options?
3) Can Microsquirt handle an optical trigger sensor or 2 ?
4) Can I use a trigger wheel with 72 slots with the optical sensor?

1. AFAIK, the MicroSquirt only handles one spark event per channel, it can't do multispark. Out of curiosity, why 3 sparks...motorcycle cylinder heads like the one in your pic, don't need them! I can understand if you've got a hemi head, and a large combustion path, and folks like Mercedes Benz, use twin plugs to do this, but mainly for emissions, as the second plug triggers a couple of msecs after the first. BMW twin plugged their heads to reduce required advance & head temperatures by cutting down on the combustion path. I know the 123 ignition guys looked at multispark for Citröen 2CVs!, but abandoned it.

2. I am not sure you can delay spark on starting via a dialog box, other than taking longer to get sync. I think once you have sync, with a good starter/battery, plus a possible a soft start setting (well retarded) at cranking RPM's you should be OK. I remember your Aprilia V twin, and twins & singles especially have much greater variation in cranking speed compared to fours. In these cases it helps to have more teeth on the trigger wheel, as the resolution is increased.

3. No problem with an optical trigger, it's ON/OFF you just need to make sure the voltage is suitable for the MicroSquirt inputs.

4. AFAIK, there is no issue with that number re starting. I know that Porsche use a 144 tooth pattern, and guys have got this to work, but the problem might be the tooth count at high RPMs. Porsche are about 8K, so a CBX1000 at 11/12K? might be an issue, but I expect an answer will come shortly. I assume you want to keep the TriSpark set up, but looking at it, I'd make a new trigger wheel and fit a Hall sensor, as you have enough room.

Personally, after looking at v3 & v2 versions with 12-1 teeth on my engine, and using a car Hall sensor, I wouldn't be going in any other direction. I've experimented/tested other systems, and overall I can get sync from 49-21000 rpm on my rig with my Microsquirts & Module boards, which is more than good enough. Even turning the engine over by hand with a starting handle and the sparks are like clockwork! I also prefer the Tunerstudio software & datalogging capabilities to most out there too.

Hope this helps
Mike