By the ignition change the original CDI becomes a battery supported ignition system. As long as all components of the CDI are working well and all parts are in a good condition the original ignition works perfectly. But when the high voltage coil and/or the pickup coils are aging, or the load capacitors in the black boxes loses slowly at capacity, then starting becomes hard work and the engine doesn't run perfect. By the change to battery ignition there is always a strong ignition spark, which is kept constant by the dynamic dwell angle even at higher revolutions. As also with the 3 1/2 the Pickup on the left side of the engine block is replaced by a light barrier printed circuit board. The ignition is applicable with 6 and 12V. A suitable ignition coil is this from Beru (BERU ZS220), but you can also use different types with a primary resistance between 2 and 6 Ohms.
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The adjustment is very easy. As an additional adjustment help a LED near the light barrier indicates the right position of the pulse disc at TDC, further adjustments are not necessary.
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| ZDG3.1 with 3 ignition curves |  |
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| Additionally you can get the complete ignition coil set with all mounting elements. |
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mounting guideline