Author Topic: Points heel issue  (Read 2569 times)

Offline BSA500

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Points heel issue
« on: 11.12. 2023 13:06 »
Has anyone had issues with wear on their points heel on the K2F magneto. I was trying to start the A7 this weekend just run it up and she just wouldn't start and has been a bit stubborn for a couple of weeks, I just thought it was the damp/cold. Pulled the plugs wet with petrol. No spark at the plugs. Surprising as Andrew had gone through this mag completely last summer and new leads plugs etc. I assumed the drive cog must have failed. I checked if it was turning and yes it was then I noticed that the points heel didn't seem to be touching the cam. It has completely worn away I had only ridden it for about 500 miles and had noticed she was getting more tricky to start which I put down to using a spare incorrect carb.
 I have had this bike for over 30 years and never seen this before, i have never had to adjust points gaps in that time they just never changed, its just very weird??. its no biggie as the bikes off until the finer weather and I have to service the gearbox but is there a bunch of dodgy points out there?

1960 A7 (57 motor to SS spec)

Online Triton Thrasher

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Re: Points heel issue
« Reply #1 on: 11.12. 2023 16:00 »
New points sets and baseplates are poorly made.  Check carefully for a loose pivot pin. That makes the gap close up.

Even the little contact points themselves can come loose on their arm.

There should be a wick under the bottom of the cam ring, with a plug of felt that sits in the round hole in the cam ring.  It should be kept oiled.

Offline BSA500

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Re: Points heel issue
« Reply #2 on: 11.12. 2023 16:44 »
Thanks for the reply. I can actually see that the heel has lost material and worn away in around 500 miles of use. I have had points that I  used for years without having to adjust(and I admit to neglecting to lube). Its just so odd

1960 A7 (57 motor to SS spec)

Online Triton Thrasher

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Re: Points heel issue
« Reply #3 on: 11.12. 2023 16:58 »
The newer points may have an inferior nylon heel, rather than the old Tufnol.

There is such a thing as special points cam grease, but I don’t know where it’s available.  I think I heard that specialists in air cooled Volkswagens used to have it.

Offline BSA500

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Re: Points heel issue
« Reply #4 on: 11.12. 2023 19:26 »
Well I will have to take it out for a closer look see and eeplace at least its an easy fix. I will get a decent set from Andrew rather than the "genuine' lucas ones on ebay ;). Like I said no rush I have gearbox oil leak to sort

1960 A7 (57 motor to SS spec)

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Re: Points heel issue
« Reply #5 on: 12.12. 2023 06:55 »
Had the same thing happen to me. A newly overhauled mag got steadily worse and would only run on fully advanced. I discovered that the points gap had closed to 1 1/2 thou. I'm used to mags running without attention for years. Now checking points has gone on the the frequent checks list.
2 twins, 2 singles, lots of sheep

Online groily

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Re: Points heel issue
« Reply #6 on: 12.12. 2023 08:52 »
It's quite common to see points gaps self-adjusting with the later Lucas steel-backplate cb assembly because the method of attachment of the fixed point carrier leaves much to be desired. But not so common I think for the heel to be worn down the way BSA 500 describes. (I infer that the problems recounted here relate to these later versions.)

Replica points kits for the steel backplate units have been of very variable quality and some just aren't fit for purpose: flimsy construction, serious mis-alignment of the contacts when fitted on a decent Lucas backplate, loose contacts, dodgy rivet holding the bent tin opening point carrier to the heel - all and more of what TT said.
I'm not sure what the quality is like of any of the bits that are available from the usual sources to be honest.

Ideally I'd always  use an earlier brass backplate if one is to be had. Although they suffer over time from worn pivot posts and oval holes in the heel, these weaknesses can be sorted, and if needs be better contacts can be grafted onto damaged or worn parts. The heels on these parts last pretty well - a bit of lube (as also says TT) is good, using the felt strip and pimple supplied.

It is also worth bearing in mind that it is possible to fit a BTH or Bosch contact breaker unit of the correct rotation. It may (depending on the individual version) require suppression and recreation of the integral keyway/ register on the male taper to get the internal timing right (or repositioning the camring), but the design of these cb units is superior to the Lucas one in my view.

As an aside, the temptation to regard these things as 'fit and forget' has to be resisted, a bit at least!
The general advice back in the day, per any number of Owners' Manuals, was that a mag should be sent to a 'Lucas service agent' every 10,000 miles for a complete strip and replacement of any worn or defective parts, with interim maintenance such as points cleaning, lube and re-gapping every 3000 miles. I'd say these days, for the miles most folk do, that annual removal and checks to the cb unit and HT pick-ups and brushes is probably enough. Simple checks can be revealing, especially in relation to oil ingress, excess armature float or wobble etc etc and are often the stitch in time that saves nine.
Bill

Offline BSA500

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Re: Points heel issue
« Reply #7 on: 12.12. 2023 12:42 »
then I am really unlucky I have the brass points plate, God hates me

1960 A7 (57 motor to SS spec)

Online groily

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Re: Points heel issue
« Reply #8 on: 12.12. 2023 13:51 »
That is definitely boring. But I reckon you're better off with the brass one despite this one-off problem.
The heels do wear - in the end - but if it's an original Lucas bit, it's a really gradual thing usually, even if a bit low on lube.
Is there any sign on roughness / damage on the camring that could have caused the heel to be ground down so quickly? Or any small part missing or detached and floating that could have got into the works and damaged either the heel or the ring?
Bill

Offline BSA500

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Re: Points heel issue
« Reply #9 on: 13.12. 2023 11:10 »
I will have a close look when time allows

1960 A7 (57 motor to SS spec)

Offline BSA500

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Re: Points heel issue
« Reply #10 on: 19.12. 2023 21:29 »
I got a good picture of the points in place and it looks like they are in fact opening but I think the plastic washer that goes under the clip that goes over the points is missing. I need to take these points out and have a good look

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Online Triton Thrasher

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Re: Points heel issue
« Reply #11 on: 20.12. 2023 10:00 »
I think the plastic washer that goes under the clip that goes over the points is missing.

It’s not difficult to know whether the little insulating button is there or not.

Post a photo with the clip moved out of the way.

Offline BSA500

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Re: Points heel issue
« Reply #12 on: 20.12. 2023 12:35 »
I have tried to find a way to reduce the image but have not found a program etc that works yet. I shall have a nose at the points later. Does this act as an insulator?

1960 A7 (57 motor to SS spec)

Offline RichardL

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Re: Points heel issue
« Reply #13 on: 20.12. 2023 13:31 »
Regarding photos, find and load the program/application “Snapseed.”  Hit three dots. Go to “Settings” and set image size to 1,366. Then, after opening a photo in Snapseed, select “Export.” The reduced file will be saved in the Snapseed folder.

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Re: Points heel issue
« Reply #14 on: 20.12. 2023 14:41 »
The spring clip blade that holds the moving point onto its pillar should be kept from metal-to-metal contact with the rocking arm, by a small plastic button sitting atop the hole in the rocking arm.