Author Topic: Ebay mistake, or not? Mag points assembly  (Read 270 times)

Online MrShifta

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Ebay mistake, or not? Mag points assembly
« on: 14.12. 2020 23:36 »
Hi guys,  I have four K2F mags, none working,  all have no points assemblies so when I went on Ebay today there was a good looking set going for £30 in 30 seconds time.  I jumped at them and won.  Hooray..........  Only to realise they are Clockwise !! 

Two questions.

 1,  if I fit them to a mag and spin it backwards ( clockwise) will it be enough to tell me if the mag works ?

2,  Does anyone know what the clockwork ones are for ?

Off now to bang my head on the wall.......


Online groily

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Re: Ebay mistake, or not? Mag points assembly
« Reply #1 on: 15.12. 2020 07:16 »
Clockwise rotation (from drive end) on Vincent twins and singles, some (few) Royal Oilfield twins and very few other makes. Most cars (GJ4 etc Lucas) were clockwise though and the cb assembly is the same standard unit on almost all Lucas rotating coil + camring mags. Camring inside dimensions were standardised very early on, across models and across makes, and armature tapers at the cb end were too.

Fitting clockwise-mag points to an ACW mag won't be a good test of anything, as the internal timing will be well out, and the points won't operate as well as they should with the 'heel' of the opening one leading not trailing. You might get some sort of spark, but it won't be anywhere near right and won't really help you with the state of the magneto. Rotation reversal on a K2F requires the right cb unit, the 'other-handed' slipring inside, and the repositioning of the camring - mix n match of those three is  a recipe for grief.

You could probably get your thirty quid back by reselling and put it towards a correct set. But it is one of life's pains in the rear that cb units are getting harder and harder to find in resaonable order, and the manufacture of the steel-backed later option seems to have come to a halt.
Anti-clock BTH points will work if you have any lying around (their sets are also handed, note) - but you may need to suppress and 'recreate' the little integral keyway/register on the male taper that engages with the armature. At full advance (if manual) the points need to open just after the flip points of the magnet.
Bill

Online Swarfcut

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Re: Ebay mistake, or not? Mag points assembly
« Reply #2 on: 15.12. 2020 08:15 »
 Barry. Maybe a ray of hope here. If they were the steel (rather than the brass ) carrier variant you will be in luck as this type is reversible.

  For next time an easy rule is that the fibre heel trails behind the pivot  as the points rotate.

 Swarfy.

Online groily

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Re: Ebay mistake, or not? Mag points assembly
« Reply #3 on: 15.12. 2020 09:44 »
On the why and wherefore of the rotation thing,  this here might provide a light lockdown diversion  . . . works nicely on bike club quiz nights anyway!
http://www.brightsparkmagnetos.com/faqs/FAQs%20about%20magnetos%20generally/Why%20are%20some%20magnetos%20driven%20clockwise%20and%20others%20anti-clockwise.htm
Bill

Online MrShifta

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Re: Ebay mistake, or not? Mag points assembly
« Reply #4 on: 15.12. 2020 13:45 »
Thanks guys, I think I will put it back on Ebay and look for a correct set.   Buy in haste, repent in leisure Eh ?

Barry.