Author Topic: 2 3/4 instruction manual  (Read 453 times)

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Offline tonyd

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2 3/4 instruction manual
« on: 12 Oct 2022 at 19:10 »
I will probably find out that I have been very silly in asking this question. In the instruction manual under the heading," Suggestions regarding irregularities in the ignition" it says:
If the ignition fails suddenly a short circuit caused by the cable connected to the nut may be assumed to be the trouble..
By removing this cable completely from the nut the fault can quickly be located. If ignition can be obtained now then the cable itself is shorting and the insulation of the same should be examined.
Are they talking about HT leads and the nut on the spark plugs caps.
Thank you

Offline cardan

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Re: 2 3/4 instruction manual
« Reply #1 on: 12 Oct 2022 at 20:20 »
Not silly Tony - the language is 100 years old. I think they are talking about the cut-out wire that was fitted to some magnetos back in the day. It ran from an insulted post on the points cover - where it was fixed with a nut - to a cutout switch on the handlebar. The connection was via a flat spring to the low-tension side of the magneto - the spring pressed on the head of the hex screw that holds the points block onto the armature. When this was grounded the magneto stopped sparking.

If the insulation on this wire failed and it touched the frame between the magneto and the handlebar switch the sparks would stop. Disconnect the wire at the nut on the magneto and all good again.

Many/most TSs these days don't have a magneto cut-out, with the engine stopped by lifting the exhaust valves.