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CDI Pulse Trigger Time Delay Circuit


Oct 27, 2013
Oct 27, 2013
workin on my racing outboard engine that began life as a 1986 Evinrude 60 hp 2-stroke outboard engine. after reverse engineering watercraft tech throughout it makes 100hp reliably as far as racing engines go.

Tried aftermarket programmable ignitions but could not get all feature desired and also was not happy with reliability, keeping batteries charged and cost of the entire system.

The stock system uses OMC's CDI2 ignition which is very unique. The flywheel has N/S magnets opposed 180 deg by S/N magnets. The CDI uses the Positve pulse generated by the single trigger to fire one cylinder and the negative pulse to fire the other. There is one CDI Charge Coil that supplies between 150 - 300V. (I thru the above in to add chaois to this thread)

The Trigger makes from .5 - 20 V , has a resitance of 40 Ohms +/- 5%.
I want to use the Silcon Chip oscilating high energy CDI with the or a pulse trigger.
I can get initial advance mechanically thru the stock throttle linkage.

MY Goal is (you have waded thru the initial Chaios)
I need then at about 3000 rpms or so begin to retard the timing (2-stroke with chamber perform better with timing retard at "high" rpms for several reasons)
a .0003 Sec Delay from Static Timing would give a 14.5 degree retard @8000RPM which is what I would like to achevie. I do not believe the delay will be constant (or linear retard rate) due to the Nature of unknown waveform of the Triggrer.(thru that in for additional chaios).

Calls to add a simple air core Inductance coil that will cause a time delay when the Pulse Trigger Fires thru it. It was suggested by a "Tech Rep" to Try 3 coils of "wire" at about 10mm dia and 3 more coils over. (do not know laymans terms for that configuration but do know the tech did not recomend wire dia and said to experiment) My share of Chaios.

Try a RC Circuit.................

The curve in the pic is close to what I hope to achieve with a timing light & (lots of angry boaters at the local ramp due to 120db noise pollution) they will also share in the chaios.

Please overlook my typo's and sarcastic humor. It seems simple.

I guess I should throw in 3000 - 8000 rpm corresponds to Frequency of 50hz - 133hz so will not get a linear retard rate / constant time delay with a simple circuit as the pulse trigger frequency/voltage will vary . Not a problem I can bestfit the curve "I hope"....................


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