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Discussion Starter #1 (Edited)
Dimensionally they are pretty much the same, though the Gen 1 is a bit deeper.

It's been mentioned before that the trip for the pick-up coil is different between the two.

My measurements were somewhat quick and dirty, but I show the Gen 1 trip strip starts at 128° BTDC with a duration of 20°.


The Gen 2 starts 157° BTDC and has a duration of 50°.


They both seem to stop at about the same place, 107°-108°. Could be they are supposed to be exactly the same, but my measurement is a bit off.

Tom
 

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Discussion Starter #3
No clue, though I don't see what there is to wrestle with. It's one of those lock, stock, and barrel things, ain't it?

Tom
 

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I'll suggest that .5 to 1 degree is more accurate than most can or will accomplish in a home garage, Tom.
It is a KLR after all, it probably won't matter 'much'. ;)
 

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The thyristor-triggering thresholds of the two rotors, a parameter influenced by the arc length of the sensor sector, may be in play.

Generation 1: I think the CDI capacitor discharges at a rate of 186,000 miles per second; doesn't need much rotor rotation to do its job.

Generation 2: Might have to wait a while to achieve total collapse of the electromagnetic field in the primary ignition coil windings, inducing a robust spark of the desired duration, before primary ignition coil winding saturation begins again . . . hence, wider sensor sector angle.

Speculation only.

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We may have discussed this issue before on this website: SOME CDI systems advance the spark, proportional to rpm, thusly: At higher rpm, the magnitude of the pulse from the pickup coil increases. The thyristor trigger threshold is reached earlier in the cycle at higher rpm; so . . . the spark plug fires sooner, proportional to rpm within design limits.

Make sense? Didn't think so! :)

Figures 10-14, 10-15; p. 203 of this reference address the ignition advance issue:

http://bennettco.k12.sd.us/cms/lib/SD01001545/Centricity/Domain/223/SMALL ENGINE IGNITION SYSTEMS CH10.pdf
 
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