The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: CrispinA10 on 15.07. 2016 16:38

Title: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 15.07. 2016 16:38
1960 A10 Super Rocket RGS replica has been running beautifully for last few hundred miles - sweet as a nut, no oil leaks and all just lovely. About 300 miles back developed a slight stutter on acceleration, so I gently filed some light pitting from the points and that sorted it. Last night on way home from work noticed similar slight stutter (which had been increasing over week or so) so this afternoon used my day off to whip the top off the Lucus K2F and dress the faces of the points again. There was some slight pitting which I smoothed off.
Put it all back together, kicked it over and - nothing. Took off magneto cap again but all looks fine. Put it back, kicked it over, but still nothing. Took out the plugs and kicked it over to see if there was a spark. There wasn't - but the plugs were completely dry. Tickling the concentric gives a healthy stream of petrol, but it doesn't seem to be getting through to the head. If I put my thumb over one of the plug holes and kick it, there isn't even a whiff of fuel. Drained the carb chamber, checked for gunge but all clean. It is a new Amal (Wassell) 930R and has been running fine. Clearly the fuel and spark issues can't be connected - can they?
Is there a well known daft-as-brush cock up relating to K2Fs and the points? I didn't take them out so cannot have anything the wrong way up or missing an insulation collar like the points I am familiar with.
Any suggestions gratefully received.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Greybeard on 15.07. 2016 17:07
I'm sure one of the forum trusty's will pop up shortly but I suggest that the lack of fuel and the no spark cannot be related. If you had a spark I would suggest squirting a little petrol into the plug holes, refitting the plugs and seeing if the engine fires at all. Focus on one thing at a time.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Triton Thrasher on 15.07. 2016 17:35
You may have left grit or grease between the points.

Wet them with petrol and drag a clean piece of paper through them.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 15.07. 2016 17:48
Logical ideas - and quite right, I need to focus on one problem at a time in case I create another. Poured a little petrol down both plug holes, kicked over, but nothing. Cleaned the points with a petrol-soaked bit of paper and again, nothing unfortunately.
Although the battery is pretty well flat, the bike always fires first or second prod, so there is something distinctly wrong somewhere...
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: groily on 15.07. 2016 18:38
What sort of contact breaker have you got? Sounds to me as if the total sudden loss of sparks is a low tension problem, and if you have the later steel backplate cb assembly it is possible that the spring on the opening point is kissing the camring following adjustments and cleaning? If it is, there'll be no sparks as the opening point is connected to low tension live on the coil and it will be shorted out. Happens often. There needs to be a good few thou clearance all the way round as the cb rotates. Occasional kissing could also explain prior misfiring, typically on one cylinder only (although a few other things could too of course). Adjustment of spring position is provided for by a slot in the springs where they are anchored to the little ear that sticks out from the backplate - a tighter arc will avoid anything touching.
If you've got the earlier brass backplate though, a kissing spring won't have this effect as the opening point is earthed anyway, and it is rare to develop a total loss of sparks after fiddling.
If you're getting regular pitting on the points after not much use, then you could be faced with a failing condenser, but you'd expect difficult hot starting as another effect of that - and you wouldn't expect total loss of everything.
It's weird that there's no obvious fuel flow either - but I suspect if the sparks came back, the thing might run, as sometimes plugs don't look very wet even when all is well. I'd try to get the sparks back first, before playing with anything else, as it won't run whatever you do if there aren't any!
(Nothing to do with a flat battery by the way - that's the beauty of the mag, doesn't need it.)
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 15.07. 2016 19:53
Not sure which backplate I have (I'll go and have a look and take a picture if possible) but didn't think I had a condenser. That's the first thing I thought of as just about every ignition problem I have had with bikes and cars has boiled down to a blown or failing condenser. Can't see anything resembling one inside the magneto. Ah. Just looked at manual and it says it's inside the armature - er, where's that? I'm looking at the Haynes manual illustration of the armature, which I assume sits inside the mag, but there is no sign of a condenser.
Having said that, it was running fine yesterday (apart from slight stutter) so not sure why cleaning points would have any effect on condenser, which I can't even see, let alone bugger up by fiddling.
Right - picture attached. Looks like steel backplate rather than brass.  Think I will order a condenser straight away, as based on experience if it hasn't packed up yet, it probably will soon. I always used to carry a spare when riding the Enfield, although I understood that electrical system slightly better. I was surprised to see that the BSA one turned around the cam rather than being fixed. All part of being a twin I suppose...
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Billybream on 15.07. 2016 20:20
The condenser is buried inside the magneto, replacement is not a simple task, its normally undertaken during magneto overhaul by a specialist.
If you want to go down the DIY route it might be best to try the Easy Cap solution supplied by Bright Spark Magneto,s, Easy Cap is a modern type of capacitor and mounted close to the points. Your points are the steel back version.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: chaterlea25 on 15.07. 2016 21:40
Hi Crispin,
Another possibility is  the cam ring has popped out and turned, with  some types of end cover this is more common than others  *conf* *conf*

John
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: KiwiGF on 15.07. 2016 22:27
The points leaf spring in the pic does look very close to the cam ring.....is that normal? Can it be adjusted to be further away? Are there any signs of it rubbing on he cam ring, difficult to see if so in the pic.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: groily on 15.07. 2016 22:49
Looking at the pic, I don't THINK the camring has jumped out judging from the fact it's still pretty flush with the housing. The ring is located by a screw-in pin which engages with a notch and said pin should be in said notch.
The spring looks close to the lower lobe of the cam, at about half past five in the pic - but the spring's arc also looks as close as can be to its smallest judging from the amount of 'tail' extending beyond the securing ear where the little screw is. Probably OK - but worth making quite sure that it isn't touching there or on the opposite, upper, ramp of the camring, because if it does it's a definite reason for a problem.
All 'K series' mags have camrings rather than a central cam. The system works fine as a rule, especially on mags like yours with a fixed camring.
The condenser is indeed on the inside as mentioned, in a recess at the drive end of the armature next to the coil. About the most awkward place it could be! It is wired between the 'nut' at the bottom of the centre screw that holds the cb unit on (low tension 'live') and the body of the magneto ('earth'), so in parallel with the contact breaker, which is what we need. It is unlikely that anything has happened to it that would kill all sparks all of a sudden though - usually they deteriorate and you get misfiring, pitted points, and poor starting when hot, which gets progressively worse.
Might be worth checking that when the points are 'closed' they really ARE closed and making good contact. It's delicate with a meter, but if you have a sensitive one you want to see 0 ohms across the points, shut, and about 0.5 ohms across them, open. That half ohm is the resistance of the primary winding of the coil, so it's not like measuring across the points on a battery & coil ignition system where you'll see 'Open Line' when they're open. Also worth checking that the brush or brass strip in the cb end cover (for stopping the engine) isn't touching anything except the head of the centre screw.
 
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: metalflake11 on 15.07. 2016 23:51
Are you sure the points are still closing when they should?
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: duTch on 16.07. 2016 03:01
 
 In case I missed something, and at risk of sounding really dumb *eek*, but does it by any chance have a kill switch that you've 'forgotten to flick on' or a button ? (it's probably the oldest catch-out in the book)
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 16.07. 2016 08:54
Yes , there is a kill button, opposite the horn button on the dip switch. I should have thought of that. Have to go out in four minutes, but this evening will give that a good wiggle. I certainly used it to stop engine when I came home on Thursday, which is the last time I saw a spark. That would be a wonderfully simple and logical solution - and somewhat easier than stripping down a mag to replace condenser. The points do open and close fuller as far as I can tell with a feeler gauge, and was running fine before, so I don't think anything has jumped or slipped. Is there a quick way to disable kill switch - can I simply disconnect a wire?
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: duTch on 16.07. 2016 10:42
 Disconnect it at the Maggie end or just leave the cover off (saves  having a bare wire to short out  *eek*),  but be ready to pull the plug leads if you need to stop it
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: muskrat on 16.07. 2016 12:44
Leaving the cover off may lead to the camring coming out. If there's a joiner in the wire between the mag and switch disconnect there or at the mag. Replace that wire with one with a bare end. Touch the bare end to the motor to stop it.
Cheers
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: nimrod650 on 16.07. 2016 20:07
Yes , there is a kill button, opposite the horn button on the dip switch. I should have thought of that. Have to go out in four minutes, but this evening will give that a good wiggle. I certainly used it to stop engine when I came home on Thursday, which is the last time I saw a spark. That would be a wonderfully simple and logical solution - and somewhat easier than stripping down a mag to replace condenser. The points do open and close fuller as far as I can tell with a feeler gauge, and was running fine before, so I don't think anything has jumped or slipped. Is there a quick way to disable kill switch - can I simply disconnect a wire?
i run the mag wire to a lucas fog light switch under seat also acts as anti theft device when parked up
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 16.07. 2016 20:13
OK, really simple but stupid question - where does the flamin' cutout switch wire go into the magneto? The only wire I can see is what I assumed was the high tension cable, which goes into the mag cap in the centre and is secured with a serrated washer, plain washer and nut. Surely that's not the cut-out wire? The Haynes manual suggests that it is, Is it really? And if it is, how on earth is the mag wired in to provide a spark - I can't see how that could work. But I do confess to being pee-poor at electrics. Preferred iambic pentameter to resistance and multimeters at school. Still baffled by the twilight world of Joe Lucas, Prince of Darkness.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Billybream on 16.07. 2016 20:19
That's the cut out wire, the ht cable or spark plug leads go into pick up carriers either side of the magneto. These must be connected to provide power to spark plugs.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Greybeard on 16.07. 2016 20:34
My knowledge, which I obtained from the book Magneto's for Dummies, (no such book) says that the wire that's connected to the centre, or side of the end cap just shorts the mag to earth via a push button kill switch originally fitted on the handlebars, (and/or an after market toggle/keyed switch, usually hidden somewhere to provide some kind of engine immobiliser). If that single wire is connected to the machines earth the magneto stops working. As long as the mag body is properly earthed it needs no other power source or external connection apart from the HT leads going to the plugs.

In the old days, anyone who knew anything about motorcycles would know that popping off the end cap or cutting the kill wire was enough to counter the simple switch idea. These days I comfort myself by thinking that there cannot be many bike thieves who know these tricks. *doubt*
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 16.07. 2016 21:04
If anyone planned nicking my Beezer they would have a hell of a job pushing it up two miles up the lane and onto the main road - it isn't going anywhere at the moment. Disconnected the mag cap centre wire and despite my best hopes, nothing. Still no spark. Didn't touch anything other than using abrasive strip (wife's nail thingy) to clean up points so still at a loss as to why no spark. Points are now spotless, perfectly gapped but still nothing. Unfortunately have to work tomorrow so no chance to delve deeper. Argggh.
Still love it to pieces though...
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: nimrod650 on 16.07. 2016 21:07
My knowledge, which I obtained from the book Magneto's for Dummies, (no such book) says that the wire that's connected to the centre, or side of the end cap just shorts the mag to earth via a push button kill switch originally fitted on the handlebars, (and/or an after market toggle/keyed switch, usually hidden somewhere to provide some kind of engine immobiliser). If that single wire is connected to the machines earth the magneto stops working. As long as the mag body is properly earthed it needs no other power source or external connection apart from the HT leads going to the plugs.

In the old days, anyone who knew anything about motorcycles would know that popping off the end cap or cutting the kill wire was enough to counter the simple switch idea. These days I comfort myself by thinking that there cannot be many bike thieves who know these tricks[quote they just chuck it into a van anwayauthor=Greybeard link=topic=10877.msg81637#msg81637 date=1468697688]
My knowledge, which I obtained from the book Magneto's for Dummies, (no such book) says that the wire that's connected to the centre, or side of the end cap just shorts the mag to earth via a push button kill switch originally fitted on the handlebars, (and/or an after market toggle/keyed switch, usually hidden somewhere to provide some kind of engine immobiliser). If that single wire is connected to the machines earth the magneto stops working. As long as the mag body is properly earthed it needs no other power source or external connection apart from the HT leads going to the plugs.

In the old days, anyone who knew anything about motorcycles would know that popping off the end cap or cutting the kill wire was enough to counter the simple switch idea. These days I comfort myself by thinking that there cannot be many bike thieves who know these tricks. *doubt*
[/quote]
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: morris on 16.07. 2016 22:31
how on earth is the mag wired in to provide a spark - I can't see how that could work. But I do confess to being pee-poor at electrics. Preferred iambic pentameter to resistance and multimeters at school. Still baffled by the twilight world of Joe Lucas, Prince of Darkness.

Very pretty looking machine you got there Crispin  *wink2*

Everyone calls a K2F a magneto but in the strict sense of the word, a magneto is just a device that makes electricity and does just that.
The K2F on our bikes contains a magneto (the square shaped part opposite to the points side) to generate power for the spark.
That's why you don't need a battery or other external power source. The magneto generates low tension power, which is transformed to high tension by the opening and closing action of the points, and it's this high tension you need to generate a spark.
This high tension is distributed to the spark plugs by means of the slipring which is driven by the magneto shaft.
The slipring is made out of a non conducting material and has a bronze insert that passes by the pick up carbon brushes and thus sends the high tension to the correct plug.
The condenser is just there to prevent the points from arcing, as this arcing would otherwise wear them out fairly quickly.

It's known that bad quality pickup brushes can leave a trace of carbon all around the slipring so the whole circumference of the slipring becomes conductive. The spark will then follow any path and end up god knows where...
Remove the rear pick up brush, and have a peek in the hole. If there's carbon on the ring it will be clearly visible.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 17.07. 2016 09:21
Unfortunately no need to be able to whip off the plug caps to stop the motor - there is still no spark with the kill switch cable removed. Off outside to have another fiddle before I have to go to work.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: mugwump on 29.07. 2016 09:22
This thread is like the episode of  Hancock's half hour show ( Brits only will be familiar with this show) 'The last page'. Hancock's frustration at the last page missing from a borrowed book.
Is there a happy ending to this story CrispiA10 ? 
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 30.07. 2016 18:31
Apologies for the delay - arrived home from holiday six minutes ago. Hoping the pixies have been in the shed and sorted it while we've been away, but they probably haven't. Full day off tomorrow before returning to work so will be trying again and will report.
Thanks for all the help so far - really looking forward to rekindling that spark in my relationship with my BSA...
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 31.07. 2016 15:56
Taken the magneto cover off and had a good long stare and fiddle again. I am reluctant to start taking things apart on the grounds that it was sparking fine until I cleaned the points, and that anything else I do could make the problem more difficult to trace. I don't think I took too much off with the abrasive paper - the gap seems to be 0.012 -0.015 depending on the exact definition of slide fit. I have taken off the cut-out wire just in case that is having an effect, although it doesn't appear to be the issue. Still no spark. I have taken the plug caps (unsurpressed) off and am holding the HT lead close to the head hoping for a spark - is there a better way? I know that mag systems don't need a battery. The reason I mentioned a charge earlier was that with my Enfield (which has a different points system) it is easy to induce a spark between the faces by separating them with a thin wooden probe, thus checking that all is well. Can't do that with cam ring set-up of course.
I noted the advice to "remove the rear pick up brush, and have a peek in the hole. If there's carbon on the ring it will be clearly visible" Looking at my Haynes manual I'm not sure exactly what the rear pick up brush is. Is it what is marked High Tension Pick-up? Or is it the Earthing Brush? I'll have a look, but if there was a carbon issue, surely it would have been apparent before. Incidentally, my mag doesn't look the same as the one on page 84 of Haynes, Fig 5.1 The Magneto Components. I did include  picture of the points end of mine and was told it was the later type. The unit was professionally reconditioned for the previous owner (and builder) and has so far done about 800 miles.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Triton Thrasher on 31.07. 2016 16:31
The spark should be capable of jumping 1/4" from the lead to the cylinder head.

The slip ring, which can get coated in carbon, is sort of visible when a high tension pickup is removed.  Check that the brushes in the HT pickups have not stuck out too far and been sitting sideways against the slip ring.

Clean the slip ring with petrol on a rag, while turning the engine over.  Remove the points, or short-cicuit the kill switch lead, to avoid shocks.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: chaterlea25 on 31.07. 2016 16:57
Hi,
BY any chance did you remove the complete points rotor?
On replacing it are you sure the rotor key is located properly in the armature?

Another possibility since the mag has only done 800miles since rebuild and the points have pitted is that the condenser has failed
There were and are a lot of unsuitable condensers being fitted *problem* *razz*
Failures of condensers have similar symptoms to yours

John
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 31.07. 2016 17:15
No, I didn't remove anything - just a light clean of the faces.
Thought I had found something just now. Following the advice to check the HT pick-ups, did so and found that one in particular was a bit loose. Checked the carbon springy things and they look OK (although not sure exactly what I am looking for). Refitted them and tried to squeeze the retainer strips in a bit to create a tighter fit, turned it over without plugs in and...nothing. If I hold one of the bare leads and kick it over, there is no hint of a shock. And I know what an HT shock feels like after an unfortunate incident with a James Captain when I was about 14. Quite a jolt.
Just how tight should those pick-ups be held in? Not too tight I assume or the carbon brush would wear too quickly.
Seems unlikely that the condenser would pack up completely at just the moment I cleaned the points, but wouldn't I still get a weak spark?
Another possibility: How critical is the tightening of the bezelled ring that holds the black Bakelite end cap in? There is a little brass triangular marker which sits in one of the grooves, but no indication of which one it should sit in. I took it off and put it back fine the first time, but could this be an issue? I have it finger tight at present.
Off to wipe the slip ring (which I assume is the thing I can feeling turning beneath the pick-ups) with petrol as advised.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: chaterlea25 on 31.07. 2016 18:40
Hi Crispin,
At this point I think you need to recruit some help from an experienced person or workshop  *sad2*
Are there any forum members in your locality who may be able to help?
These magnetos are fitted to quite a few different makes of bikes so not necessarily a BSA owner???

John
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Triton Thrasher on 31.07. 2016 18:45
If it won't even shock you, there's more wrong than a dirty slip ring.

Can you check whether the centre screw that holds the points plate on has electrical continuity to the casing?
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: RichardL on 31.07. 2016 20:12
And I know what an HT shock feels like after an unfortunate incident with a James Captain when I was about 14. Quite a jolt.

Crispin,

You've only had ONE shock from HT? You must officially hold the forum record for the fewest such shocks.

I have a few ideas that I don't think have been shared yet, however, I'm not really optimistic any of them hold the answer if all you did between sparking and not sparking was clean the points.

In no particular order:

1. Is the correct notch in the cam ring sitting over the cam ring stop peg and is the stop peg visible and not broken? One of the pictures below shows two stop pegs and covers (though, there is only one in the mag). The other picture shows the stop peg location with the cover in place. If the stop peg is missing or broken off it is possible that the cam ring is rotated such that the points open when the brass on the slip ring is not in contact with the pickup brush.

2. It is possible that the connections of the plug wires within the brush holders have come loose or otherwise degraded. With so much trouble going on, it would not be a bad idea to renew these connections anyway, meaning, cut back a little wire for a fresh end for the pickup to screw into. (we assume you are using copper plug wire and not carbon-impregnated fabric filament plug wire).

3. Be sure the springs that hold the brushes in the holders are seated at the bottom of the holes in the holders. They may be pushed down with a very small screwdriver (I have also used a cut-off toothpick). 

I think the idea of finding a bit of local help is a good one. It doesn't mean you couldn't do it yourself. Sometimes when we are frustrated we just go blind to the big picture and it can really help to have another set of eyes on the issue.

Richard L.

Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: duTch on 31.07. 2016 22:32
 
Quote
Another possibility: How critical is the tightening of the bezelled ring that holds the black Bakelite end cap in? There is a little brass triangular marker which sits in one of the grooves, but no indication of which one it should sit in. I took it off and put it back fine the first time, but could this be an issue? I have it finger tight at present.

 I think the 'pointer' may be an anti-rattle doodad, and you need to screw the cover on so it's snug...?

 Without re-reading the whole thread, is it possible you've crossed the plug leads? Swap them over again anyway.. *conf*
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: RichardL on 31.07. 2016 23:26
Dutch,

Apparently, Crispin is geting no spark when testing by placing hand on engine and touching tongue to lead end, so, issue of crossed leads might be there, but not the basic problem, me thinks.

Richard L.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: duTch on 01.08. 2016 00:55
 You;
Quote
Apparently, Crispin is geting no spark when testing by placing hand on engine and touching tongue to lead end, so, issue of crossed leads might be there, but not the basic problem, me thinks.

 Me; brainfart *shh*
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 01.08. 2016 19:00
Many thanks for all this - I am working through ideas one by one.
However the suggestion about asking someone who knows a lot more about mags than I do and who lives nearby is a good one.
Have just phoned a bloke named John who lives in the next village. You can tell he's a great bloke because he keeps a pair of Triumph GP racers in his sitting room and has had loads of BSAs including a Goldie. He went through most of the ideas posted here, and after gathering that I was reluctant to take off the mag and take it apart for detailed study, he said: "and if nothing else works and you're not in a hurry, I might be able to take a look at it."
I'm to clean off that slip ring with petrol, check the length of the carbon brushes and if nothing happens, phone him back...
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 04.08. 2016 16:46
Right - progress I think! Perhaps my magneto isn't dead after all. Have just discovered that if I kick the bike over with the points end cap removed completely, then there is a faint spark at both plugs. Pale and weak, but a definite spark. Put the end cap back on (with or without the kill lead) and nothing.
What could cause that? The carbon brush in the cap looks clean and springs in and out as it should. There is no visible damage and it looks in excellent condition.
I'm assuming that the mag should generate a big fat spark rather than a Tinker-bell style flicker - might that mean the condenser did give up the ghost at exactly the moment I cleaned the points?
Really looking forward to some suggestions - day off work tomorrow so I can fiddle at will.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 04.08. 2016 16:59
This is the type of cap I have - not sure if there are varients.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: metalflake11 on 04.08. 2016 17:23
Firstly, the brass pointer thing is there to sit in the serrations in the end cap to stop it unscrewing, period. With the cap off the end of the mag, take the plug caps off the H.T. leads and hold the ends close to the engine and kick it over........... No plug, no cap, just the end of the lead close to the engine. Let me know if the spark improves. I'm on line for a bit and will reply quickly.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Triton Thrasher on 04.08. 2016 17:50
Ok, it sparks with the points cover off.

Does it spark with the cover screwed on, but no kill switch wire attached to the cover?

Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: metalflake11 on 04.08. 2016 17:54
Ok, it sparks with the points cover off.

Does it spark with the cover screwed on, but no kill switch wire attached to the cover?

No.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 04.08. 2016 18:42
The spark is no better using the bare end of the HT lead with no cap.
No, it doesn't spark with the cap on whether the kill wire is attached or not. Unless..... of course there is an intermittent fault and there is an element of coincidence.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: RichardL on 04.08. 2016 19:14
Take a look at the attached image. It appears you are missing an insulating cork washer between the steel washer and the end-cap body. I believe that would explain it.

Richard L.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Triton Thrasher on 04.08. 2016 19:30
Take a look at the attached image. It appears you are missing an insulating cork washer between the steel washer and the end-cap body. I believe that would explain it.

Richard L.

The brush holder certainly does have to be insulated from the magneto casing.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 04.08. 2016 20:04
My response appears to have disappeared into the ether rather like my washer - basically it said Arggggh! Then well spotted mate to Richard L - then thanks to everyone else who has been so, so helpful. Off to grovel around on the bricks in attempt to find the washer...
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: RichardL on 04.08. 2016 20:24
I think what you would be looking for is the earth brush holder washer. I suppose you could get it from Bright Spark Magnetos, Priory Magnetos or SRM. SRM shows it on their website, though, I guess I was expecting to see a shouldered washer. I've never really seen one before because both of my end caps are the bakelite type.

Richard L.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: metalflake11 on 04.08. 2016 22:19
Richard L is right about the insulating washer being missing. Have you got some more H.T. lead? If so change the leads (easy job) and try again with them close to the engine. When you unscrew the connectors give the inside a clean up.

Personally, I don't think your condenser has gone as they usually work when the mag is cold, and start to fail when they get warm. Yours sadly, is stone cold now. *sad2*

Keep going, we'll get there!
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Triton Thrasher on 04.08. 2016 22:43
So, if you replace the insulating washer (where did the old one go?) or remove the brush, you may have a running engine.

Although with no brush you have no good way to stop the engine.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: RichardL on 05.08. 2016 01:02
Although with no brush you have no good way to stop the engine.

Well, the brush is there, so I'm sure TT meant, "with no wire between the brush and a kill switch you have no way to stop the engine." On the other hand, up until now, with no insulating washer, it has been pretty effective at stopping the engine.

Richard L.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: duTch on 05.08. 2016 01:40
Quote
Although with no brush you have no good way to stop the engine.


Well, the brush is there, so I'm sure TT meant, "with no wire between the brush and a kill switch you have no way to stop the engine." .......

Richard L.


 I read it as "...or remove the brush,...", just to test it with the cover on... (?)

 
Quote
On the other hand, up until now, with no insulating washer, it has been pretty effective at stopping the engine

        *smile*
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: RichardL on 05.08. 2016 03:30
Yep. You're right. Missed that.

You can always stop the engine by pulling off the plug caps or, maybe, popping the clutch too fast.

Richard L.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: groily on 05.08. 2016 07:34
This always had the smell of a low tension problem.

But what is quite intriguing is how, if the only thing that was ever done to the instrument was a bit of a clean-up at the points, the insulation arrangement of the engine-stop brush could have altered.

With a meter, the brush should show no continuity to the alloy with the cover off, measuring from the carbon or from the stud/tag for the stop wire.
With the cover on, you'd expect a very low resistance reading from the stop wire to the bike, representing the 1/2 ohm resistance of the low tension winding (from cb centre screw head to main magneto earth), plus any small resistance across the brush and spring.

If the bike ran perfectly before, and if the problem is the simple fault described, the bike should run again with the brush removed or freshly insulated, using any suitable washer in fibre or plastic.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 05.08. 2016 08:55
Failed to find the washer in the fading light last night, although it was a good three weeks ago that I must have displaced it while removing the cap so not surprising. Will attempt to start the bike without the cap, and if no luck, try new leads. I ordered a new box of brushes too, which should arrive today. Then I'll attempt to source or make a new insulating washer - I assume fibre would work as well as cork.
Getting there....many, many thanks to everyone.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 05.08. 2016 09:16
Can't believe how lucky I am to have Roadstar British Motorcycles 18 miles up the road at Dover. Just phoned and they have in stock both types of brush holder washers for K2F magnetos. Off I go.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: bsa-bill on 05.08. 2016 09:22
Quote
Will attempt to start the bike without the cap,

be aware the cap keeps the camring in place, just check it hasn't moved outwards and turned when your about to replace the cap
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Greybeard on 05.08. 2016 09:30
Jumping in with no experience of that type of endcap: if you're talking about the big washer; I can't see how that insulates anything; surely it's just to keep water out of the points. I guess without it the cap may go on too far and cause a problem.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: duTch on 05.08. 2016 09:53

 My interpretation;-
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 05.08. 2016 11:23
Just back from bike shop at Dover - was offered the black ring thing but after explanation came home with the cork/fibre washer. The bike is now outside ticking over like a dream and twittering gently - off for a quick blat and will then post again. Yes!!!
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 05.08. 2016 12:02
It is running perfectly - a heartlifting blat around the country lanes with the sun shining. I'm so pleased and grateful. Although it turned out to be something so basic I have at least learned a lot more about the magneto along the way. I do recall that when I removed the cap to clean the points that turning the nut on the kill lead loosened off the brush holder inside - the insulation must have slipped out at that point and disappeared into the frame below, creating my very own and highly effective permanent kill switch.
Again, thanks to everyone who helped solve the problem - much appreciated.
Right - off for another celebration ride!
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: Greybeard on 05.08. 2016 13:37
 *smile* *smile* *smile* *smile* *smile*
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: RichardL on 05.08. 2016 14:22
Fantastic news. Great to hear you got it running. What's the report on starting when hot?

One more piece of advice: Toothpicks work quite well for removing bugs from between teeth.

Richad L.
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: CrispinA10 on 05.08. 2016 14:59
It's always been absolutely fine starting from hot. First or second prod and the same from cold. I understand that the previous owner (and builder) had the magneto completely refurbished. It was just that he hadn't allowed for some idiot to lose the insulating washer...
Thanks again for spotting the missing component - I should have posted that picture of the cap earlier (although at that stage had no reason to think it might be the issue)
 *smile*
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: groily on 05.08. 2016 17:19
Great news. This has to be one of the best 'for the want of a nail' stories - but luckily the horse isn't lame, nor the battle lost. Excellent result!
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: metalflake11 on 05.08. 2016 21:42
All's well that ends well!
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: duTch on 06.08. 2016 00:23

 What will we do now for entertainment *eek*
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: muskrat on 06.08. 2016 06:18
NEXT *pull hair out*
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: duTch on 06.08. 2016 08:52

 
Quote
What will we do now for entertainment *eek*

  But as serious as I like to be, I'm stoked for yea- and heps of kudos to ol' Eagle Eye Richard for spotting the lack of insulating washer *beer*
Title: Re: I've killed my spark and fuel supply - how on earth...?
Post by: RichardL on 06.08. 2016 16:46
Thanks, kindly, Dutch. I finally got one right after a hundred or so wrong guesses.

In a way, this reminds me of the Plymouth Trouble Shooting Contest I was in in high school. Every year, every Southern California high school would send two auto shop students to the Los Angeles Plymouth plant where maybe a hundred identical cars had been jiggered-up with the same engine problems. A couple of the problems I always remember were the wood block jammed under the fuel pump arm and (sorta like the washer) no copper in the phony 12V wire to the ignition coil. We came in 5th place (no ribbon).

Anyway, just glad Crispin can happily ride his A10 until the next challenge.

Richard L.