An Odd Charging Modification on Le Mans 1000

[MikeW]

I've been asked about an unusual modification to the charging circuit of a Mk4 Le mans 1000. The 80 ohm 2 watt resistor (47) has been swapped out for a 1000uf 24V capacitor. The resistor is connected to the same point on the diode block as the charge light and the other end connects to positive via the starting circuit fuse.

I'm told that the bike appears to be charging fine so I'm curious if anyone has heard of this mod and any claimed benefits.

[Kiwi_Roy]

The 1,000 microfarad capacitor should give the rotor quite a kick when you turn the key On, much higher than the bulb I think, the instantaneous current through the rotor will only be limited by its resistance.
The thing is a split second later the capacitor will be fully charged and the current will drop to zero, it must be relying on the residual magnetism after that.
I think the 80 Ohm 2 Watt resistor should have worked well.

[Kiwi_Roy]

I thought I would compare this to the Bosch alternator on my Convert, it was originally excited by a tiny bulb 63 Ohms when cold and the equivalent of 138 Ohms when hot.
I recently changed the dash over to all LEDs, of course the LED didn't draw enough current to excite the rotor so I put a pair of the old lamps in parallel.
Why two lamps, just because. I think it does help it excite with two lamps and they just lie in the bottom of the dash unseen.
Really the Capacitor and the lamp are quite similar in a way, they both cause a spike in the rotor current, the capacitor will be higher but its over long before the engine starts to turn over, the lamp is still supplying ~80 mA when the bike is idling. The 80 Ohm resistor should be supplying ~ 150 mA.
Note:
I do realize that the lamp current drops off as the engine speed increases, so will the resistor current, the Capacitor though is over long before the bike is running. Interesting idea though.