G80s contact points

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capercaillie
Posts: 6
Joined: Mon May 15, 2017 3:01 pm
Location: Rhondda. UK

G80s contact points

Post by capercaillie »

Hi.
I have a Matchless G80s 500 single, about 1954, although I cant be totally sure of the year.
It has magneto ignition and I am trying to set the points.
The rotor moves in a clockwise direction and the points are open approximately from the 5 o clock position, to the 1 o clock position and are closed between 1 - 5 o clock.
Is this right ?

Thanks
Chris.
Last edited by capercaillie on Mon May 15, 2017 6:14 pm, edited 1 time in total.
Groily
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Posts: 2151
Joined: Thu Jul 04, 2002 1:00 am
Location: NORMANDIE FRANCE

Re: G80s contact points

Post by Groily »

Whether you have an SR1 or an N1 the points are designed to be open for much longer than they are shut. Doesn't take a lot to recharge the primary (when the points are closed) - so what you have sounds about right in terms of 'open & shut'.
If you have an SR1 then it is important to be sure the cam is set on the armature shaft in the right place on its taper.
You want the points to start to open just after (a few degrees after) the magnetic flip of the armature (not before). (There are 2 flip points per rev, note, one is redundant on a single.) There are very good instructions available on setting the thing correctly in the Lucas workshop instructions for the SR series. See, for one source, page 8 of the pdf here http://www.brightsparkmagnetos.com/libr ... %20SR4.pdf
You'll be able to see whether the cam is roughly right by turning things and noting when the points start to open relative to the flip of the rotor. If it looks roughly right, chances are it is actually correct - but no guarantee on that of course!
capercaillie
Posts: 6
Joined: Mon May 15, 2017 3:01 pm
Location: Rhondda. UK

Re: G80s contact points

Post by capercaillie »

I have established that it is a lucas N 1 Magneto.
The points seem to close at TDC, is this correct?
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