Author Topic: A10 1958 misfire  (Read 518 times)

Offline Ian

  • Moving Up
  • **
  • Join Date: Jan 2016
  • Posts: 5
  • Karma: 0
A10 1958 misfire
« on: 18.01. 2016 23:11 »
I was fettling my A10 when it suddenly developed a misfire on one barrel. Prior knowledge made me suspect the magneto carbon brush which on inspection had come adrift from the holder.
So I replaced the missing brush but the misfire persists. Could the missing brush be causing a short of some kind. Any ideas how to remove the brush without dismantling the mag from the engine?
All help gratefully accepted

Offline beezermacc

  • Resident Legend
  • *****
  • Join Date: Dec 2011
  • Posts: 994
  • Karma: 39
  • Not for the purist!
    • Priory Magnetos Ltd.
Re: A10 1958 misfire
« Reply #1 on: 18.01. 2016 23:48 »
Remove both pickups and blow it out by firing air in through one of the pickup windows. If you haven't got an airline you can try blowing it out with a rubber tube or pushing a tube in and sucking but make sure you use a tube which is smaller than the brush or you could choke. Check your slip ring for carbon traces and clean it with some fine emery on the end of a rubber tube pushed in one of the pickup windows. Make sure you are not using poor brushes - rub them on some white paper to see if they make lines like a pencil; if they do, bin 'em.
Priory Magnetos Ltd - A10 spares, magneto and dynamo refurbs. www.priorymagnetos.co.uk

Offline Ian

  • Moving Up
  • **
  • Join Date: Jan 2016
  • Posts: 5
  • Karma: 0
Re: A10 1958 misfire
« Reply #2 on: 19.01. 2016 23:18 »
Beezermacc
Many thanks for the swift reply and helpful tips,
Ian  *smile*

Offline BSA_54A10

  • Wise & Enlightened
  • *
  • Join Date: May 2008
  • Posts: 2018
  • Karma: 32
    • BSA National
Re: A10 1958 misfire
« Reply #3 on: 20.01. 2016 06:32 »
If you removed he pick up holder and there was no brush in it then yes.
There is a big lump of conductive material sitting on or near the slip ring shorting it out to the magneto case
Bike Beesa
Trevor

Offline Ian

  • Moving Up
  • **
  • Join Date: Jan 2016
  • Posts: 5
  • Karma: 0
Re: A10 1958 misfire
« Reply #4 on: 31.01. 2016 20:48 »
Bsa_54A10
Cheers for the advice, blew mag threw with air compressor engine started first time  *smile*