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I believe when the magneto is moved to the stop position it contacts the bottom of the stop switch bolt and thus grounds the capacitors to stop the outboard ….
no HD expert but the condenser basically serves to prevent excessive sparking across the points when it/they opens. The collapsing magnetic field created in the primary winding by open points causes a counter rise of voltage as the coil tries to sustain the magnetic field . This counter EMF tries to jump across the point (s) which eventually burns their surfaces but the condensers absorb this kickback sparking.
The proximity of collapsing primary coil’s current induces the secondary coil’s high voltage which reaches the sparkplug (s) s and tries to establish a ground path by jumping the .020 gap.
sometimes the “plug body” grounded in the threads is the initial point of entry of the returning voltage but said voltage must have continuity back to the coil body otherwiseit may try to jump anywhere it can (watching it in operation in the complete darkness can pinpoint some “extra” jumping site wherreas all 100% of the spike needs to jump the plug gap.
Some engine actually have a ground wire connecting the mag plate body to the engine body to facilitate this.
MR. Mohat article on the “Magic of magneto” is a much better read !
if your ” guinea pig” only felt a week jolt well it is weak and weakness may come from a weak magnetic field induced by weak magnets
have you tried just holding a screw driver near the magnet (s) to see if they pull strongly ? are the coil laminates adjusted close to them
have you tested the ohms values on boot to primary wires (post results)
Joining AOMCI has priviledges 🙂