NGWClub®, Inc.

For those of you worried about if a stock stator can keep up:

I just installed a voltmeter in the shelter lid.

I am charging at 13.8 at 1100 RPM when combined with my LED headlight and tailight, even with the fan on.

Near redline, that goes down to 13.6. I imagine the EFI components and the ignition spend a lot more time energized at higher RPM and contribute to this slight decrease.

In any case, I have plenty of margin on power.

I forgot to mention that I also have a MOSFET reg/rectifier combo on this bike.

That bike looks familiar! Amazing what your capable of. Good work!

Thanks Tim!

It's been a lot of fun. You should swing by sometime and take her for a ride!

Sorace,

I am thinking about working on ignition control... Did you find that it was an improvement? The stock mechanical advance is a little touchy for my taste.

Uh oh..... The bug bit again.

I'm thinking about creating a CDI unit. I've shamelessly borrowed from some other circuits that I have seen around on the internet and modified them to fit my needs.

It seems to work ok on a circuit simulator: I get nice high-voltage pulses to the coil on the rising edge of the tach signal, as well as a nice 10 volt square wave from the tach output. This should work well for the megasquirt. If any of the EE people on here would provide a sanity check, I would greatly appreciate it. The LTSpice model and the library I used for the SCR is attached.

Just when I thought it was safe to read your posts, now you had finished the F.I., you go and hurt my brain again!

(don'tya just hate it when folk keep proving how little you know)

Very cool. Just picked up a '78 myself, and have quite a bit of experience with MS in automotive apps. I even have a micro laying around for no other reason than I got a good deal on it and "I'll find somewhere to use it"

If my carbs wind up being junk, I'll probably go the same route you did. Nice work.

Looks good Toehead. Just spotted your spice model post today, for some reason. From what I remember about capacitive discharge ignition design, it's important to match the HV supply impedance to the charge time used for the storage cap. Guess you could put a scope probe on D2 cathode and check for sagging under a variable load. Seems like most designs I remember used 400+ volts for cap supply voltage.
I went with a high energy inductive system for mine. Four low-inductance, high current coil-on-plug coils (from a late model Ford V8) are triggered by 4 logic level IGBTs (irgsl14c40l) driven directly by megasquirt. They are just shrink-tubed and zip-tied to the bike's frame for cooling. Used megasquirt's constant dwell control to set peak coil current to about 17 amps, I think it was. No current limiting other than the supply fuse, but no problems so far!
Using 4 coils also means that each plug can get the same ignition polarity, a big benefit over waste-fire, even without the high energy stuff.
Thought I did a NGW write-up on using the Ford coils but can't find it now. You can sort of see them in my sig picture.

Thanks for the feedback. Yes, I think that I'll need to spend some time on the scope to make sure that this circuit can handle the spark frequency required. I'll try not to zap myself

I made some changes after I found an IC specifically made to drive this sort of circuit. Instead of relying on a blocking oscillator, I figured this might be more robust and a little less dependent on my transformer winding skills .

I also changed to a full-bridge rectifier circuit. Hopefully this is a little more efficient to help lower charging times.

I've got the transformer, IC, and some fast-switching NPNs on the way. I already have all the diodes and caps.

I'll let you know how it turns out.

What are you using for a trigger, if you don't mind me asking?

That HV power supply looks very robust; push-pull outputs, feedback regulator; could do the job alright! Will be following along on this.
My trigger sources are a small 36-1 crank trigger wheel and hall sensor (mounted in the stock gl1100 location, rear of crank), and a hall sensor mounted to detect the fuel pump drive cam, to provide a cam signal.
The stock gl1100 reluctance pickups requires a zero crossing detector that the microsquirt has, but does not work very well in this app. The reluctance ic used by microsquirt has a timeout feature that is shorter than the time between Honda triggers, so no signal could be detected below about 750 rpm, I think it was! The only way to disable the timeout feature was to also lose the zero crossing feature. Could have converted the reluctors to hall effect, that doesn't need zero crossing, but decided the 36-1 wheel was cheaper to build (on the gl1100 anyway) and more accurate.

Thanks for the feedback. It's nice to not have to design stuff in a vacuum.

Since that last post I have moved some stuff around on the power supply side to contain some nasty flyback spikes I was getting when the transformer switched. It looks much better now.


I also might try to use a trigger wheel at some point, but I might have to get creative on a mounting location. I wonder if I can get something small enough to fit inside the stock breaker point housing on a 1000.... I know it won't be as accurate as with a crank wheel, but it might be easier to get to work.

i got my 36-1 from here http://trigger-wheels.com, fits inside the 1100 spark generator housing.

they have some as small as 2"...

Wonder how C5 would interfuse with Micro-Megasquirt or the like? I believe their trigger wheel is 90 teeth and optical reader.

I think you could do fuel only pretty easily, as they have a tach output.