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I am restoring a 1967 250 Scrambler, all the wiring diagrams show a red, yellow, and white wires coming from the alternator. This one has (1) red, and (2) black wires. Anyone have any idea how to wire this up? I can start it up, and runs fine using the 6 volt battery, and it will continue to run with the battery disconnected, but has only 5 volts coming from the red wire and nothing from the black wires. Turning on any lights, kills the ignition. Any help will be appreciated. Coop

Hi,

is this a narrow or a wide case model? I suppose it's a n/c, because only some of these have a "magneto" ignition, allowing to run the engine without battery. I also suppose your bike has no regulator/rectifier box, neither the big black (steel sheet cover) box or a smaller, aluminum housing. Only the alternator for the wide case models was equipped with 2x yellow/1x red wires by the factory. Yours have either been modified/exchanged later by an owner, or it happens to be a n/c model.
Can you tell the engine no.? This would make it easy to specify your alternator type/ignition circuit scheme. Btw, detailed fotos are always useful.

cheers Hans

p.s. You can find the schematics of the 250 SCR magneto circuits in the workshop manual http://www.motoscrubs.com/Ducati_Manuals/4-5-speed-shop.pdf, p. 46 and p. 48, respectively. But beware, it is a >50MB download.

Engine case # is 101338, narrow case.

OK, then this schematics shw your electrical system:



Cable colours should be white, yellow and red. This was apparently changed on your stator.


Hans

Found my problem. Sometime in the last 50 yrs, the 3 alternator wires became damaged at the point that they exit the engine case. Someone patched in 2 black wires and 1 red. The wire coating and wrap were damaged and shorting out on the case. They even tried using duct tape to cover the repair. I removed the clutch housing and am making appropriate repairs.
HINT!! I used a small oil filter wrench to hold the clutch hub while using an air impact wrench to loosen the hub nut. Works fine.
Thank you to you great folks who replied to my problem.
Coop