ALTON Testing

Martyn Goodwin

Well Known and Active Forum User
Non-VOC Member
Recently I took my Comet out for its first long ride. Up till then I had only undertaken trips of under 50 miles, and in all had covered a total of 450 miles. My recent trip was of 190 miles and my Comet performed wonderfully. About 50 miles from home I noticed that the ammeter suddenly was indicating discharge and before I actually got to my home I had flattened the battery – fortunately with a Magneto ignition it was no great problem. I checked the fuse that I have in place between the battery and the voltage regulator output and it was intact. I also checked the earth connections and they seemed to be fine as well.

Suspecting that something was amiss with the Alton unit, once back home I contacted Alton by email asking them to advise me what checking procedures they recommend so I could verify the correct operation of the Alton and the voltage regulator. Their reply that includes the recommended testing regime is reproduced below that may be of use to others on this forum.

QUOTE::This is our testing procedure:

Two static tests (engine off):

[1-1]test continuity between the 2 wires from AC generator. There should be CONTINUITY between those wires.

[1-2]test continuity between one (or the other) wire from the AC generator and the Alton body. There should be NO continuity.

Two dynamic tests (engine running):

[2-1]disconnect the AC generator from regulator. Start engine. Check AC voltage between the 2 wires of AC generator. This voltage should reach 20-22 volts AC as soon as you rev up engine (let's say at a high idling rpm).

[2-2]connect the regulator to the AC generator and anything as it should be. Start engine. Check DC voltage between the 2 terminals of battery. This voltage should reach 13 volts DC as soon as you rev up engine (let's say at a high idling rpm).


I eventually tracked down the cause of my “no electrical power” problem. Today, as part of another task, I removed the side cover of the motor of my comet and found the reason why the Alton was not producing any output.

The Alton drive cog retaining screw had come out and allowed the drive cog to separate from the Alton shaft. The drive cog, the retaining screw and the washer were all in the bottom of the timing case; fortunately it appears that no damage was done.

I used brake and clutch cleaner to remove all traces of oil from within the thread in the Alton shaft and also from the thread of the screw then reassembled the drive cog to the Alton applying Loctite 248 on the screw thread. Hopefully this will be a permanent fix.