There's no telling,,it's precise trigger point is subject to several variables.
What You have is a Magnetic Triggered CDI.
The Basics are simple.
A) CDI "Black Box"
This has a Capacitor which acts as a "Storage Tank" somwhat like a battery.(excepet it only HOLDS electricity,,it does NOT Produce it)
The Box also has a semiconductor SWITCH,,,which is normally closed.
It gets Triggered OPEN,,,and allows the Stored Electricity to flow to the Ignition Coil/Spark Plug Coil.
B) Charge Coil in the Magneto.
The Mag's Spinning Magnets swinging by the Charge Coil,,,which generates Electricity.
That juice is what Fills the Capacitor in the CDI BOX with electricity.
C) TRIGGER COIL,,,,also known by many other names,,"Pulser Coil" is one
It too operates on the principle of a Magnet swinging by a Coil to generate Electricity.
The Electricity it produces controls the SWITCH inside the CDI Box,,which in turn controls the Capacitor's Discharge to the Spark Coil
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So ,,,Magneto is Simultaneously doing 2 Separate Distinct "Generating Functions",,,,, thus acting as 2 Sources of Voltage Output.
1)Charging
2)Triggering
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You're asking about the TRIGGERING Section.
Specifically,, WHEN the Trigger Point occurs.
The Only way to KNOW is to have access to the engineering specs.....which is always Unavailable to public.
Yet,,,when we are Told Ignition TIMING specs,,,,
and the Adjustment Procedures to achieve those specs,,,
In a 'round-about way All That is an indication of the Position/Orientation of the Parts of the Trigger Mechanism.
If Your Bike has TIMING MARKS,,,,and You Align those marks,,,
Whatever Position the Pickup Coil and the "Flywheel Bump" are in,,,is When it Fires.
The "Bump",,the Raised Section on Your Flywheel is actually called a "RELUCTOR"
You can Watch it "Real Time" with a Strobe Timing light.
It "freezes" the appearce of those 2 at the Instance of Firing,,and ya can See the relationship.
TYPICALLY,,,,Most Reluctor/Pickup Combos will trigger anywhere from
Shortly AFTER the Reluctor Aligns with leading edge of Pickup Coil----to--- MIdway Point.
GENERALLY,,,the "Window" of Triggering is Very Narrow in terms of Degrees of Crank Rotation..
Understanding That,,it forms the basis of "Shadetree" Rule of Thumb CDI Magneto Timing.
>>If You Position the Leading Edge of the Reluctor in approx the Center of the Pick-Up,,,
Ignition Timing will be VERY CLOSE to "correct".
Provided that Crankshaft is in correct position.
Or in Simpler Terms,,,
"It's a Safe Guess that Reluctor's Leading Edge when CENTERED in the PickUp,,,is Very Close to Actual Trigger Point"
That's APPROXIMATELY where it Will Spark.
So,,For Example when assembling an engine,,You can Arbiratrily install the Mag Assembly in that Approximate Position and be certain that it's "Close Enough" to Start and Run.
And then go from there with Fine Tuning,,or Actual Correct Timing Procedure.
In Any Case,,,,understanding the How's Why's helps Initial Assembly,,,,,getting Parts Bolted on in the correct GENERAL Area.
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Reason why PRECISE Trigger Point is Not Easy to Determine for WE-The-People.. us End Users,,,,
is that there's a Bunch of Variety in the Construction and Specs and Tolerances.
All that is Juggled by the Engineers to acommodate different conditons,,,or to Compensate for operational characteristics.
One Common example is that the Reluctor/Coil Relationship is set-up to deal with the effects of Varying RPM.
The Voltage Generated does not simply APPEAR.
It Rises>Peaks>Falls.
When Monitored it Creates a WAVE PATTERN.
Specs are Juggled to Use only a Portion of the RISING Ramp of the Wave.
That is LESS THAN Peak Voltage,,,but ABOVE MINIMIMUM Voltage.
The Logic is simple,,,,that Prevents TOO EARLY a Triggering,,especially at Slow Speeds.
And Prevents Too LATE a Trigger at High Speeds.
Being Set to a Trigger Threshold at LOWER Than Peak Voltage insures "Excess Voltage" is available to Reliably trigger the CDI Box's Switch and Make the Spark.
The Surface Speed of the Flywheel is quite High.
At even Medium RPM's it's Flyin' Past the Pickup.
At some theoretical Extreme RPM it moves "Too Fast".
ELECTRICALLY,,It will still Trigger the Spark.
But the Crankshaft will have moved Past where it's Supposed to be.
In Real Life,,,Some degree of that theory is actually in play,,it's effect does exist.
Engineers can Manipulate that phenomenon to best advantage in a variety of ways .
They may chose to MINIMIZE the Effect----Use Hot Magnets,Responsive Coils,,,HIGH Voltages,,,,and Trigger off only a Tiny Percentage of the Volts.
That makes Trigger Point VERY Precise at High Speeds.
But at Lower Speeds,,,,such a Sensitive SetUp will Trigger EARLY as the Reluctor just Creeps Up to Coil.
"Creeps up" is obviously a Relative term.
Or,,they can do Vice Versa,,,,make a "Tight Coil",,,Low Voltage,,,Very Stubborn to generate X-Volatge.
This Requires the Reluctor to be IN The Window of the the Coil before it'll Trigger.
So it Reduces chances of Early Firing.
Different Mechanical Arrangements,,,,,construction of Reluctor and Coil,etc are also possible.
Reluctor may be Just Non Magnetic Metal,
Or it may be a Magnet.
Pickup may be a Simple Coil on an Iron Core,,,
Or it may be a Magnetic Coil---Maybe WOUND on a Magnet,,,or have Magnetic Pole Pieces adjacent to it.
Each different arrangement creates Different Operational Characteristics and Mannerisms.
They do SAME THING,,,but behave different.
Some are Fast,some are Slow.
Some are wide range,others are very narrow.
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CDI Principles are VERY simple.
Anybody could make one with "household items" and less than $10 worth of stuff from Radio Shack.
In actual practice,,,CDI Circuits get QUITE Complex.
Electronic Ignition Advance has Multiple Voltage Controlled "Switches" ganged together to Change When the Spark Occurs at the Spark Plug
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While all those variables make it impossible to say WHEN spark will occur SPECIFICALLY,EXACTLY,,,without knowing Allll the Details,,,
It's very "Safe and Easy" to say that ANY CDI Reluctor WILL Trigger a Spark when it's Within the Proximity of the Pickup Coil.
It Must,,that's the BASICS of how it works.
To Narrow it Down,,,we can ASSUME that when the Reluctor is Centered in the Pickup,,,,,,That will be Very Near the Precise,Actual Trigger Point.
We can go even a bit Further towards precision by understanding that Most All CDI's are built to Trigger on Leading Edge of Reluctor,,,,,and Not Before.
So if You Look at the Leading Edge of the Reluctor--The "Bump" on the Flywheel,,,
And the 1st Half of the Pickup Coil which the Reluctor will swing across,,,,
Odds are HIGHEST that is where Trigger Point will Occur.
And in terms of Igntion Timing,,and Crankshaft Position in Degrees,,,,,,
That's gonna be VERY,VERY Close to CORRECT Ignition Timing Position.
Plus or Minus a Tiny,Tiny amount.
Hope any of that Makes Sense,,,let alone helps answer your question,,lol