The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: owain on 11.02. 2019 21:37

Title: Can ignition timing go faulty during use?
Post by: owain on 11.02. 2019 21:37
It's been a few months since my A10 suddenly stopped working whilst I was out riding. The next day it was incredibly hard to start (I had to run down the road and drop into second) and when it did start it would only stay alive with a lot of throttle. The day after that it wouldn't start at all.

The magneto had been reconditioned by APL magnetos in June last year. Both cylinders have 150psi. And I recently replaced the auto-jumble concentric carburettor with a brand new concentric carburettor ( a 928, .240 main jet, .106 needle jet, throttle slide 3, needle pos. 2).

I'm back at trying to get the bike working again now. Fresh fuel in the tank yesterday but I'm getting little sign of life out of it. Perhaps the occassional 'pop' out of the carburettor but no kick back from the pedal (I remember a poorly timed B33 almost snapping my leg with a strong kick!). Even with the new carb not being correctly tuned, I'd expect there to at least be splutter or a brief moment of continuous ignition. The only thing I have left to think of is that the timing is off. It is an auto-advance timing btw. The irritating thing is that I ensured that the timing was set up exactly (11/32" BTDC with auto-advance unit wedged in full advance) and it worked grand for a few weeks. So how could the timing go bad so quickly? Is it possible that it rotated out of it's position during operation? Is that normal to happen with only  a few weeks worth of short distance riding?

Would love to hear what advice might be out there. Thanks!
Title: Re: Can ignition timing go faulty during use?
Post by: morris on 11.02. 2019 21:50
Quick check; remove the pickups and have a peek inside if there’s a trace of carbon on/around the slipring. Bad quality brushes leave a trace of carbon and will create an arcing path for the spark to go anywhere except to the plugs
Title: Re: Can ignition timing go faulty during use?
Post by: chaterlea25 on 11.02. 2019 22:06
Hi Owin,
Has it wet sumped while standing?
A sumpful of oil can prevent getting a good kick over
A quick stationary check of where the points open without stripping off the timing cover will tell a lot, clean the points too
they should open about top dead centre, (there or there abouts is fine)
Is there a good spark at the plugs?

John
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 11.02. 2019 22:09
Following on from morris, check that when the points open, the plug lead to the cylinder on compression is the one which is contacting the brass segment of the slip ring. We have all swapped the leads over by mistake. Pick up brushes must be clean and free to move. Remove the points cover, in case the maggy is earthed somehow and check for good sparks at the leads.  Timing can slip, but you should get some sparks if the maggy is being driven. Like they say, most carb problems are ignition.

 Swarfy.
Title: Re: Can ignition timing go faulty during use?
Post by: Greybeard on 11.02. 2019 23:02
Ignition timing will change if the points gap changes. Too wide, spark retarded. Too close, spark advanced.
Title: Re: Can ignition timing go faulty during use?
Post by: Black Sheep on 12.02. 2019 06:49
Yes, the timing can slip especially if it has recently been set. It's not too difficult to check with the calibrated stick down the plug hole technique. It will give you a fair idea if there's anything badly amiss.
Title: Re: Can ignition timing go faulty during use?
Post by: a10gf on 12.02. 2019 06:57
Some causes that needs checking\eliminating.

Removing the plugs and 'earthing' them, do they show a good, strong spark even with gentle kicking.

If a good spark, check timing, the autoadvance could have slipped on the magneto, has happened to me (with fixed gear) due to not securing the nut properly, while riding the bike behaved worse and worse then stopped net a few miles from home.

Regarding carb & fuel supply, after kicking (or pushing) for a while and getting no start, there should clearly be 'wet plugs' + fuel smell from silencers.
Title: Re: Can ignition timing go faulty during use?
Post by: Klaus on 12.02. 2019 08:12
Ignition timing will change if the points gap changes. Too wide, spark retarded. Too close, spark advanced.


Are you realy sure?
I say its the other way.
If the gap is bigger, the contactbreakershue is closer to the camring and the shoe is tuching sooner the ramp. This means the ignition is advanced.

cheers Klaus
Title: Re: Can ignition timing go faulty during use?
Post by: duTch on 12.02. 2019 08:15

 
Quote
.....? Is it possible that it rotated out of it's position during operation? Is that normal to happen with only  a few weeks worth of short distance riding?...

 Only you the owner/ Rider can verify that with an easy check
Title: Re: Can ignition timing go faulty during use?
Post by: Triton Thrasher on 12.02. 2019 08:53
If you’re the slightest bit worried about points and timing, check the points and timing.


If the points close up, the ignition retards.

If the drive pinion slips on the tapered end of the armature shaft, the timing retards.
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 12.02. 2019 08:54
Points and Timing. I'm with Klaus on this one. On a conventional fixed points/ moving cam set up, opening the gap brings the fibre heel of the moving point, at rest, closer to the cam. So the cam has less distance to rotate to open the points, so advancing the timing. Logic would say it does not matter whether the cam is fixed and the points rotate. False logic? So we need a definite answer from our electrical department.

  Checking the timing with the ATD in its retarded position.....Someone measured the piston height, but fool that I am, I  did not make a note. It must be somewhere on the Forum.....a useful dimension for a quick check before things get a bit oily.

 Swarfy.
Title: Re: Can ignition timing go faulty during use?
Post by: Rex on 12.02. 2019 09:29
Personally I would investigate the carb and in particular the pilot jet/idling circuit. Do the plugs get wet? Will it run with a squirt of fuel in the cylinders or in the air intake?
Title: Re: Can ignition timing go faulty during use?
Post by: Greybeard on 12.02. 2019 09:36
Ignition timing will change if the points gap changes. Too wide, spark retarded. Too close, spark advanced.
Are you realy sure?
I say its the other way.
If the gap is bigger, the contactbreakershue is closer to the camring and the shoe is tuching sooner the ramp. This means the ignition is advanced.
Yes, you are correct. I was thinking of car distributors where the cam is inside the points heel. Of course on our bikes it's outside of the heel. Sorry if I confused anyone.

Anyway, points gap affects timing.
Title: Re: Can ignition timing go faulty during use?
Post by: duTch on 12.02. 2019 09:52

 
Quote
.....The magneto had been reconditioned by APL magnetos in June last year....

 Yeah but the fact you had it 'reconditioned'  means Jack-shit as per my earlier reply to another thread on this..... did you have it  checked out by the refurb guy,  and/ or an independant someone as I inferred  you should??
 If you don't follow up or feed back on suggestions,  we can't help much as we'd like

Title: Re: Can ignition timing go faulty during use?
Post by: Colsbeeza on 12.02. 2019 10:24
Hello Owain,
All that has been said should dictate your check list. However, if a solution does not happen after all that you may need to get the magneto bench-tested. I had my magneto timing shift soon after having it overhauled and then checked again. So a magneto fault is a last resort. Took me months to pin that down. The serviceman could not explain why it happened.
Cheers Col
Title: Re: Can ignition timing go faulty during use?
Post by: orabanda on 12.02. 2019 11:38
Are the teeth on the fibre gear stripped?
Been there, had that happen....
Remove the points cover and check that the points rotate when engine is turned over.
Title: Re: Can ignition timing go faulty during use?
Post by: Triton Thrasher on 12.02. 2019 12:41
Quote from: Greybeard
Yes, you are correct. I was thinking of car distributors where the cam is inside the points heel.

In a car distributor, points gap closing up retards the timing.  Same as in a magneto.
Title: Re: Can ignition timing go faulty during use?
Post by: Greybeard on 12.02. 2019 12:45
Quote from: Greybeard
Yes, you are correct. I was thinking of car distributors where the cam is inside the points heel.

In a car distributor, points gap closing up retards the timing.  Same as in a magneto.

 *red* I think I'd better just shut-the-f*ck-up.
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 12.02. 2019 22:11
Thanks for the quick replies. The bike hasn't wet sumped (I have a plumbing valve to completely cut off the oil flow when I'm not using it). I'll check the pick-ups first seeing as that's the simplest and will have a look at when the points separate with a marked paintbrush through the spark plug hole. I haven't taken the mag off the bike yet Dutch. I was a bit fed up with the bike when I lasted posted and have been putting my efforts into rebuilding my A75 engine during the winter. Mag removal and sending it off to get tested is gonna be my last resort right now.

When plugs are removed, I can see a bright blue spark with a reasonably mild kick...but it doesn't spark every time. Out of 10 kick attempts, I'll get a spark 7 times-ish.
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 13.02. 2019 18:04
An update on the problematic A10. I checked the magneto plugs and they appeared clean. Timing was very slightly off, so I reset it again to 11/32" BTDC in full advance. I'm happy with the timing there but when I kicked it over there was just a very brief combustion but died immediately. No signs of life since. I cleaned the points on the magneto again and tried kicking it over. No luck. I switched the high tension cables over. Still nothing.

I even ran down the road and dropped the bike into 2nd gear a few times but not a single sign of combustion.

Here's the strange part...after running down the road with it, I got out the spark plug tester and plugged in between the high tension cable cable and the spark plug. I kicked the bike over. No light to indicate a spark. I then detached the spark plug and just earthed the spark plug tester to the chaincase. Big bright light came on with every kick. Indicating that there is an electrical input. So I tried plugging a spark plug back onto the end of the spark plug tester (ensuring a very good connection) and earthed the spark plug on the chaincase...No light, albeit a very dim light and no visible spark.

Scratching my head as to what is going wrong. There is an electrical input reaching the spark but no spark is forming :/
Title: Re: Can ignition timing go faulty during use?
Post by: Triton Thrasher on 13.02. 2019 18:43
Does a new plug spark?
Title: Re: Can ignition timing go faulty during use?
Post by: muskrat on 13.02. 2019 19:09
G'day Owain.
Do you have resisted or non-resisted plug caps?
Cheers
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 13.02. 2019 19:50
Brand new spark plugs but no spark. I'm running NGK B6HS spark plugs. So there shouldn't be a resistor in them and this spark plug type has worked relatively well for me to this point. I've also checked the spark plug gap (0.018"-0.020").

I'm totally baffled though. Spark plug tester is showing a bright light with a gentle kick when it is grounded to the chaincase but as soon as I add a spark plug and ground that to the chaincase. No light or spark.
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 13.02. 2019 21:25
High Tension Electricity is funny stuff and can defy all logic. Test the plugs by substitution with known good ones. Further  checks before you condemn the magneto are to remove and inspect the carbon brush between the magneto body and armature, located under the brass slot headed screw adjacent to the nameplate. No electrical path here means the HT current cannot return to the armature to complete the HT circuit. With no load the HT current can usually find a way back, but is unable to do this when there is a load in the circuit... as I said it was funny stuff.

    A brass contact breaker carrier usually also has a carbon brush under it to earth the points to the body, the later steel points carrier is a slightly different electrical set up and does not have this brush. An inherent flaw with these penny pinching universal rotation steel points is that if the steel spring blade touches the cam ring, the LT circuit bypasses the points and the result is no sparks or erratic running.

 If these are in order I would suspect condenser failure.

 Swarfy.
Title: Re: Can ignition timing go faulty during use?
Post by: Bsareg on 14.02. 2019 09:17
On the subject of brushes, you may have a set of those crappy lucas pickup brushes fitted . They would throw carbon over the slip rings causing leakage to earth. Might be worth a rag in the pickup hole to give the slip ring a wipe. If tgat works buy some brushes from Brightspark.
Title: Re: Can ignition timing go faulty during use?
Post by: Rex on 14.02. 2019 09:48
Lucas copy maybe, but not genuine Lucas. Right what you say though...I've had carbon smeared around the slip ring through that duff batch of brushes some years back.
Title: Re: Can ignition timing go faulty during use?
Post by: bsa-bill on 14.02. 2019 10:02
Had this problem a few years back, cured it the quick way (fitted Pazon), however if earth is a suspect remember the maggie has an earth brush at the timing case end, I did not check mine at the time (confessional ) so might be worth a punt
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 14.02. 2019 10:16
    I got to feeling this thread is getting familiar, so I have just read all of Owain's posts.  Cheered me up as it looks as if the curse of the A10 is currently residing in North Wales, and a long way from me.

    This bike has had a lot of time and effort spent, but seems to be mostly an unreliable runner, with one or two episodes of really showing what it can do.

  I reckon if there is an award for perseverance in the face of adversity,  Owain would win by a landslide. Makes another forum member's oil feed problems look like a walk in the park.

  Like all reluctant motors, it can only be  electrical, carby, or mechanical.  Time to stand back and consider what's what, and make sure these three elements are set up correctly.  My thought is that the magneto, despite a rebuild, is the weak link. Providing the charging circuit is reliable, a Thorspark system is a cost effective and reliable solution, allowing the magneto body and armature to be retained but with the benefit of electronic switching and no permanent alteration to the magneto. It also times the sparks in both cylinders exactly the same.  Compared to another overhaul or a new magneto  I know where I would be inclined to punt my cash.

    Spring is in the air and the open road beckons......you need this fixing soon.

  Keep on spannering,  Owain


 Swarfy.
 
Title: Re: Can ignition timing go faulty during use?
Post by: RDfella on 14.02. 2019 11:23
Swarfy's comment 'Makes another forum member's oil feed problems look like a walk in the park' presumably refers to me. I'd happily swap the ignition problem for mine. In my case the lack of oil flow is merely the latest in a long line of irritating faults. Sort of the straw that broke the camel's back.
Ref Musky's post - the danger of using resistor plug caps with magnetos is widely underestimated. I once posted the details of testing which proves resistor caps put a massive load on the mag, sufficient in fact to cause the windings to fail.
Title: Re: Can ignition timing go faulty during use?
Post by: groily on 14.02. 2019 14:04
A few thoughts for what they're not worth, if it's indeed a mag thing.

First - have you got close to 0 ohms from inside plug caps to carbon brushes on pick-ups? With the brush, spring etc there'll often be a small resistance, few ohms maybe. But if loads of ohms show up, or 'open line', then the plug cap isn't attached correctly.

Secondly, small variation in points gap isn't the problem here I don't reckon. It affects things slightly, but as long as the gaps are somewhere close to correct and the points are squeaky clean, it should work. A good wheeze is to take an old plug, grind off the earth electrode, and stick that on the HT lead. With a good 4mm-ish gap, you should get a smart crack of a spark at kickstart speed, no problem.

Third, Swarfy's point about steel cb assemblies - the blade must not kiss the camring or it's bye-bye some or all sparks.

Fourth, a quick HT test  . . . if you put a meter on the Resistance scale from the brass of the slipring with a pick-up off, and the other probe to mag body or a good earth, what do you see? Should be c 5000 ohms typically on a K2F. Open Line says a break in the winding, or that slipring-to-coil contact is absent. There should be no problem in this department  . . . but you never know.

Fifth, ref possibility of timing having altered  . . . If the ATD assembly hasn't moved and the teeth haven't stripped, what does the keyway on the cb backplate's male taper look like? Does it still exist and does it engage properly with the female tapered bore on the armature? If the cb is not correctly positioned, the thing will work badly, or not at all, as the internal timing will have been lost. The keys are fragile and can be wrecked by clumsy fitting of the assembly, also as a factor of age and loads of 'on-and-off'. Hard to feel with the mag on the bike if the drive is connected, but with it off the machine (or with just the ATD off so you can feel what is happening), can you see that the points start to open just after the flip points of the armature (which you should be able to feel easily)? (The key can be reclaimed using a little broach made out of, say, a bit of blade from a small reamer, if need be.)

Sixth, it's a tough one to test, but I wouldn't be totally surprised if the condenser(s) that will be in there have failed, even though the problem isn't the typical 'just when hot'. The hassle here is that you can't test the thing while it's wired to the primary winding, and it's made worse by the fact it will be potted in resin and bloody hard to get at. But if all else tests good and it's not a fuel / valve / other problem, that's maybe where you'll have to go next, unless you want to go electronic of course.
Title: Re: Can ignition timing go faulty during use?
Post by: RichardL on 14.02. 2019 14:15
...and let me fill in where Groily is obliged not to. Assuming you have the magneto off, or maybe perfect reason for taking it off, put in an EasyCap from Brightspark Magnetos in place of the original (or, maybe even, standard replacement) cap.

Richard L.
Title: Re: Can ignition timing go faulty during use?
Post by: chaterlea25 on 14.02. 2019 15:04
Hi All,

Quote
Fourth, a quick HT test  . . . if you put a meter on the Resistance scale from the brass of the slipring with a pick-up off, and the other probe to mag body or a good earth, what do you see? Should be c 5000 ohms typically on a K2F. Open Line says a break in the winding, or that slipring-to-coil contact is absent. There should be no problem in this department  . . . but you never know.

Digital meters are a poor choice for this test, more often than not they will show open circuit, the connection at the slipring is just a push fit
The very low voltage applied by a digital meter, most often sees this as an open circuit
Something like the old AVO Mk8 analog meters are needed to get a real reading

John
Title: Re: Can ignition timing go faulty during use?
Post by: groily on 14.02. 2019 17:16
Not with you on that John. A digital meter will do the measurement just fine. They don't 'more often than not' show an open circuit on a continuous coil - at least none of the four such meters I have here does! (Nor does the analog one, perfectly true.) This applies to still-good original windings from eg Lucas, Bosch, BTH and the rest, as it does to rewinds.
The slipring to coil connection on rotating coil mags is a lousy bit of work really, but the push-fit has been with us as the standard method since before WW1, and never really got improved. A plastic grub screw (or something) might have been a good idea, maybe, but there's norralot of playspace and the angles of dangle are awkward.
Absolutely crucial to test continuity when fitting sliprings, as it's all too easy for there to be an open circuit, and then arcing inside the slipring, which does things no good. We want to see exactly the same resistance from armature earth (spindle) to brass on slipring as we see from spindle to the bare spike on the coil before the slipring is fitted. Always a very good idea to clean out a slipring that is to be reused with a small number drill - but better still to replace with a decent modern job, as they're not expensive in the overall context, and the dielectric strength of old ones may have degraded: putting seemingly-good ones in the HT line off a coil tester and heating the ring up will often show how badly, as the current required to get a spark through often goes much too high with temperature.

But I'm pretty confident I haven't come across a continuous coil which any of my digital meters shows to be open line. Hundreds of coils with a break will work on an independent tester due to the spark jumping inside, indeed they'll work often almost to the makers' specs (eg Lucas' "2 amps at break for 5.5mmspark across  three-point test gap") which confuses things, but a break is a break for a' that as Rabbie Burns didn't say. And a break only gets worse until it doesn't allow the spark to get through.

Ref Richard's kind comment, not in the least in selling mode, honest! A WIMA 220nF job as fitted by Dave Lindsley and many others, the caps used by Andrew Beezermac, and the caps used by a number of others do a really good job. Rolled paper, ceramics wired or solder-mount, whatever. And some of the old mica ones from way back remain good almost indefinitely as far as I can see, having tested them from all eras, back 100 years or even more.

I have a graveyard of extracted modern capacitors chez moi, though (hundreds of, literally) and it is sadly the case that a lot of repaired mags with perfect rewound coils and other parts are let down by the use of capacitors which aren't that great in this application. 
Whether that's the case here remains to be seen when other causes of grief have been eliminated. As I said, hopefully not, cos it's a pain in the backside to fix  . . .

Title: Re: Can ignition timing go faulty during use?
Post by: chaterlea25 on 14.02. 2019 20:14
Hi Bill,
The slipring connection as you say is the weak link
I have found that this will show open circuit on the armature when tested with a digital meter from the brass segment to the core
If you remove the slipring and test from the HT "spike" the winding will read OK
My experience has shown me that the higher voltage applied by an analog meter will "make the connection" and get a reading through the push in spike where a digital will not

In use I believe that centrifugal force will make a good enough connection so the "spike" and slipring segment do not burn away ????

Digital meters can give false readings when circuit testing on 6 or 12v electrics  *problem* where a simple test lamp
would show up a dodgy connection
I own 2 Fluke meters which were at the top end of the price scale when new, luckily they were supplied my my job
plus an assortment of analog testing stuff gathered over the years

John




Title: Re: Can ignition timing go faulty during use?
Post by: owain on 14.02. 2019 21:11
Thanks for all the tips guys, I really appreciate the advice. I'll try out the tests suggested on the magneto this weekend. I tried cleaning the slipring today by removing the plug and taking a clean cloth to it. Still no change in the symptoms. I recorded a video as well which may help to illustrate the problem as well (https://vimeo.com/317319823 (https://vimeo.com/317319823)).

I need to sort out of the circuitry on the sidecar before making the decision to swap to an electronic ignition instead. i.e. the battery charges fine without the sidecar attached but when I've plugged the sidecar up, there is a huge amount of resistance in the circuit and battery dies not long after but that's for another time! First port of call is to get the bike going! Plus I sorta like the concept of an independent ignition system that doesn't rely on a battery (I remember the stator cables vibrating loose from my stator on my Triumph trophy and the battery died in the middle of nowhere!  *lol*)

New carb, Reconditioned mag and plenty of compression...It should be running like a dream!  *problem*

Failing the tests, I'll take the mag off the bike this weekend though!
Title: Re: Can ignition timing go faulty during use?
Post by: groily on 15.02. 2019 08:07
Hi John,
Thanks for the additional comments. I shall have a play next time I'm faced with an open circuit on an armature, and see whether the analog jobbie will show continuity when one of the digitals doesn't!
But as a general comment, there are lots of slipring connections that are bad, with a small gap inside due to the design's not being so hot. I would never continue with reassembly of a mag if I couldn't see absolutely the same HT resistance with the ring on as with it off, using any meter, because arcing in there leads to failure over time. The number of rings with pinhole damage caused by this is significant - not so much with K2Fs, but certainly on a lot of others. In extreme cases there's a complete breakdown of insulation between ring and armature spindle or between the boss on the ring and the surrounding brass of the armature end cheek.

Sometimes HT spikes have been cut too short to suit a replacement ring; sometimes it's necessary to tin the HT spike to get a bit better fit in the tiny inner hole in the slipring; sometimes things are just filthy dirty; and sometimes the insulation on an original coil's HT take-off is too thick to slip into the outer hole of a replacement slipring (and that section of the ring needs opening out to allow full penetration (!)) - but in the end I strongly believe every armature should conform to the 'no difference' requirement and be tested for it after the bearing race and any shims/flinger etc have been fitted, as well as before. Rotating forces and vibes may well make good a connection that isn't so brilliant, but it's not a place to take chances as it's a PITA to revisit. This particular thing can drive a bloke mad sometimes, and take up disproportionate time, but I reckon it's worth the effort to get to 'happy'!
Title: Re: Can ignition timing go faulty during use?
Post by: Greybeard on 15.02. 2019 09:15
...This particular thing can drive a bloke mad sometimes...
Yup, I think he is nearly there!
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 17.03. 2019 21:25
An update on the A10: Sadly still no sign of life. I removed the mag and tested for a spark on the workbench. I was getting a good bright and consistent spark with a flick of the wrist on the bench. Placed the mag back into the bike...No spark.  *problem*. I took the spark plug out of the cylinder and grounded the spark plug directly to the mag with an electrical cable. Nice spark again. Placed back into the cylinder: No spark.

The slipring is new from having the mag recently renovated and don't think the mag is the issue (Although I could still be wrong). It seems to me that the spark plug isn't grounding when in the cylinder. My theory is that oil has leaked from the rocker box cover onto the the spark plugs and ran down the threads. Insulating the plug from the cylinder. Although this sounds a bit too unlikely to have happened to both spark plugs at the same time.. The pain in the ass is that I then cleaned the cylinder and spark plug threads with degreaser and used fine grit sand paper to expose bare metal. Still no spark! I even secured a piece of electrical cable from one of the cylinder base studs to the magneto to guarantee a path to earth the spark plug to the mag. All to no avail. I'll repeat these steps again tomorrow and hope for a different result but at this point I feel like I'm grasping at straws  *sad*

Just re-read  RichardL's post about easycap from Brightspark magnetos. Sounds interesting, there is no capacitor on my K2F as it is at the moment.
Title: Re: Can ignition timing go faulty during use?
Post by: Triton Thrasher on 17.03. 2019 21:46
How do you know there is no spark inside the cylinders?

That issue of the plugs failing to conduct through the threads never happens.
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 18.03. 2019 08:44
Owain..The Thrasher is right, the plug/cylinder joint is not where the problem lies. You should get nice big fat sparks from the end of a bared plug lead to any part of the engine unit. The system will only generate sparks that will fire a plug under compression if a capacitor of the correct rating is in the circuit.  So, looks as if the magneto in its present state is the weak link. Once you have sparks, making sure they appear regularly and at the right time and place is your way forward.

    Easycap is a very cost effective and reliable alternative to revive an otherwise serviceable maggy.  Or a case of  talking things over with whoever renovated the mag....If it was you, get a second opinion, 'cos something basic is not right.

 Good luck.

 Swarfy.
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 18.03. 2019 09:08
Thanks again for the tips!. Of course, It is an assumption that there is no spark in the cylinder as I'm not getting any sign of combustion when kicking the bike over or running down the street and dropping it into 2nd gear. I fitted a new concentric carb onto the bike as I initially thought a worn carb (bought from an autojumble) was the original cause of poor starting. Even if the the air/fuel mix is way off with the new carb fitted, I thought there would at least be a pop from the engine...

Taking your advice on board. I'll twiddle with the carb settings this evening and see if that makes any difference. Failing that I'll send the mag off to be looked at by a different company for a second opinion!
Title: Re: Can ignition timing go faulty during use?
Post by: chaterlea25 on 18.03. 2019 13:29
Hi Iain,
The fault you describe can be due to loose bearings in the magneto and or bad earth brushes,
I have seen cases like this but really cannot offer a great explanation as to why it happens
I am presuming that you checked the fibre mag drive gear ?

John
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 18.03. 2019 16:15
Checked the fibre gear and it looks solid. I just tried turning the air/fuel mixture screw in and out sequentially (half a turn at a time) on the carb with no success. Worth trying a different main jet before I remove the magneto? Otherwise, I'll just take the magneto off and send it to again to a different mag guy.
Title: Re: Can ignition timing go faulty during use?
Post by: Klaus on 18.03. 2019 17:02
Hi owain,

get off the fibregear and look for scratches at the rear side. Sometimes the the tapers are in such way ,that the gear is just against the timingcase. In this way you can fit the gear and the magneto turns, only for a few turns you have the right ignition point, but the taper doesnt fit proper.
I had this, and it drive me mad.

Cheers Klaus
Title: Re: Can ignition timing go faulty during use?
Post by: RDfella on 18.03. 2019 17:44
I have read several of the posts on this thread but maybe not all, so forgive me if I’m re-covering what others have said.
Owain says no spark in the cylinders. How does he know? Is the head off to see? He says there’s a good spark on the bench, so I suspect this is not a magneto problem. If he lays a plug on the cyl head (or any metal part that’s earthed) he should get a spark. If not, try holding the end of the HT lead ¼” away from the head. If still no spark, try another HT lead – maybe his are carbon instead of copper core, or the plug caps are resistor type.
Oh, and BTW, his magneto has a capacitor / condenser - it wouldn’t work without one It’s inside the armature.
Given there’s a good spark on the bench, is the magneto timed correctly when on the bike? It is actually turning when the engine turns over? Do the plugs come out wet, indicating fuel is getting to the cylinders? Is the fuel fresh? I once spent an hour or so trying to start my B31 to no avail. Wouldn’t even fire with a push start. Reason? The petrol was about a year old. Fresh petrol and it started within a couple of kicks.
Title: Re: Can ignition timing go faulty during use?
Post by: Triton Thrasher on 18.03. 2019 17:47
If you want to be sure there is petrol in the combustion chamber, put a teaspoonful in through each spark plug hole.
Title: Re: Can ignition timing go faulty during use?
Post by: Ted_Flash on 18.03. 2019 18:19
I seem to remember that a colourtune plug lets you see if there's a spark inside the cylinder?
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 18.03. 2019 18:35
I tried changing the main jet from .240 to .200 (the size that was last on the bike when it was running) but still nothing. I also checked the timing again and it seems spot on and checked the gap between the points. All seems fine there. The spark plug tester shows there is electricity getting to the spark plug i.e. bright orange flash. I can't check for sure whether there is a spark in the engine, however before I cleaned the points I was getting a bright light from the spark plug tester but no spark at the plug. Since then, I've been getting a spark when I've earthed the spark plug but I'm not quite as confident in relying on the spark plug tester anymore. Coupled together with the lack of any combustion, it led me to believe that I've not been getting any spark in the cylinder.

The fuel in the tank (which is definitely not air tight) is no more than 2 months old. I also tried spraying 'engine starter' through the carb today to try and get any sign of life out of it but still nothing. I'll check the magneto fibre gear again and will drain the tank and place new petrol into it. Plugs do come out slightly wet after several unsuccessful kicks and the magneto appears to turn as I would expect when the engine turns over.
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 18.03. 2019 19:35
Owain.  With both plugs out, turn the engine over until one cylinder is on its compression stroke...finger in the plug hole trick. Then remove a magneto pick up. Look down the hole.  If the brass slip ring segment is visible, that is the the lead that goes to the cylinder about to fire.  No brass segment....that lead goes to the  other cylinder. Easy to mix the leads, could be as simple as that. Forget the carb, should easily fire a few times on a spray of " start yer bas***d."  Leave the points cover off in case there is an unintended earthing of the magneto.  Test plugs by simple substitution.

 RD and Klaus' observations are well worth considering, before you take it all apart.

 Ted...you would need good eyes to kick and look at the same time, but once running a colourtune is fascinating to see in action.

 Swarfy.
Title: Re: Can ignition timing go faulty during use?
Post by: duTch on 18.03. 2019 21:46

 I was also going to suggest switched plug leads, but Swarfo had it ccovered, nevertheless.....

 For what it's worth, and without going back to the beginning- if I recall, the problem started when the bike was running fine but cut out suddenly while riding....
Title: Re: Can ignition timing go faulty during use?
Post by: berger on 19.03. 2019 00:54
owain have a look at the points spring thing and make sure its not sometimes catching the cam ring. get hold of the centre bolt with some pliers and when it is nearest to the cam ring see if you can shake it about and make it touch the cam ring, if you can get a fag paper between the two without it gripping it -that isn't your problem--. just a thought I had after I had read previous posts and noted you had constant 15 thou valve clearances, otherwise I was going to say your followers had worn out and no valve lift ;) *shh*
Title: Re: Can ignition timing go faulty during use?
Post by: ironhead on 19.03. 2019 03:08
owain,
you mentioned an "orange' flash with your plug tester.
It should be blue/white for a good ignition system, usually orange is a sign of a failing condenser.
I use a Briggs n Stratton 3 point spark tester. If the spark doesn't jump this, the engine , no matter what kind, will not start. The best test tool I've ever bought for finding ignition problems.
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 19.03. 2019 07:55
duTch..  You're right. I re-read the whole thread and watched also watched Owain's  video again.  I reckon it is all down to the lack of sparks under compression, and a nut and bolt inspection of every part of the magneto is needed.  Ignition is the number one place to look when an otherwise well performing motor just stops. A Thorspark type of system is starting to look more attractive.

 Owain.. We all assume the motor is OK mechanically and the magneto is being driven.

 bergs.. Good timely reminder if you have  later type points with a steel backplate. Yup, another fine penny pinching design.

 Swarfy.
Title: Re: Can ignition timing go faulty during use?
Post by: BSA_54A10 on 19.03. 2019 11:03
owain,
you mentioned an "orange' flash with your plug tester.
It should be blue/white for a good ignition system, usually orange is a sign of a failing condenser.
I use a Briggs n Stratton 3 point spark tester. If the spark doesn't jump this, the engine , no matter what kind, will not start. The best test tool I've ever bought for finding ignition problems.

He is using a red neon in line spark tester.
I have 4 of them because I am always leaving them on customers mowers.
The logic behind them is you can use them outside to check if a spark is being made and grounding through the plug
A good spark is of course blue white so a bit hard to see in daylight even with a 3 point tester.
If it gets a flash at compression then a spark is grounding via the plug, although it can be running down the side of a contaminated middle electrode and not jumping the gap.
For testing the strength of a magneto the best tool is the sliding electrode gap spark tester, however the longer the jump, the thinner the spark.
A good magneto will jump better than 1 full inch in air.

And the easiest way to make said same tool is to poke the ends of 2 HT leads into an old Bic Biro tube.
secure one side and allow the other to slide.
Gently & slowly pull one wire back till it no longer sparks then measure the distance between the two wires.
Back in the day they were called spark intensifiers and the favourite bodge was 2 firemans brass buttons 1/2 inch apart inside a garden hose.
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 19.03. 2019 12:52
Trev.. I remember them, usually found on  Evinrude and Johnson 2 Stroke Outboards. The idea was that if a plug fouled, the spark would jump the internal air gap in the booster and this would clear the fouled plug somehow. Bit of a disappointment if you opened one up to see what was inside. Lifting the plug cap from the plug to make an air gap was the way we cleared fouled plugs on cheap knackered 2 strokes, James, Bantams, Fanny B's, and these days the same trick can be used on your reluctant mower or strimmer.

    Before the days of vehicle emission tests I made my own (a couple of pointed nails in a plastic tube) to keep a real oil burner running, rather than having to take the plugs out when the oil fouled them.  They were also hyped as a fuel saving power boosting wallet emptying must have.   

 Swarfy.
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 19.03. 2019 14:02
UPDATE: It's alive and running again!!!  ;D

I switched the cables over this morning and it started first kick. I tried switching the cables over much earlier on during this process with no luck. I think when I took the mag out of the bike and thoroughly cleaned the points, slipring, etc cured the non-sparking/weak sparking problem but then attached the cables to the wrong spark plug. This issue has caused no end of frustration for me and it seems so simple now. Thank you all for the troubleshooting advice, I think I would have given up if this problem had persisted for any longer!
Title: Re: Can ignition timing go faulty during use?
Post by: RDfella on 19.03. 2019 14:48
Glad to hear that. Sounds like you had two problems, which invariably confuses. Fortunately, forums like this give one the moral support to carry on whereas otherwise one might give up.
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 19.03. 2019 15:43
Owain... Well done for getting a runner. After all the doom and gloom you were foiled by an error we all have made at some time. Check the oil and give it a little local run... just in case.   

 Spring is here, happy days.

 Swarfy.
Title: Re: Can ignition timing go faulty during use?
Post by: duTch on 19.03. 2019 21:55

 Good stuff- lets just hope it keeps running well... *beer*
Title: Re: Can ignition timing go faulty during use?
Post by: BSA_54A10 on 20.03. 2019 09:16
Trev.. I remember them, usually found on  Evinrude and Johnson 2 Stroke Outboards. The idea was that if a plug fouled, the spark would jump the internal air gap in the booster and this would clear the fouled plug somehow. Bit of a disappointment if you opened one up to see what was inside. Lifting the plug cap from the plug to make an air gap was the way we cleared fouled plugs on cheap knackered 2 strokes, James, Bantams, Fanny B's, and these days the same trick can be used on your reluctant mower or strimmer.

    Before the days of vehicle emission tests I made my own (a couple of pointed nails in a plastic tube) to keep a real oil burner running, rather than having to take the plugs out when the oil fouled them.  They were also hyped as a fuel saving power boosting wallet emptying must have.   

 Swarfy.

Yep thems the things and that is exactly where they get used.

And the real funny bit for me is the number of times I get called in for a "Mower won't start " service.
Put the plug tester on and that tiny bit of extra resistance is just enough to make the spark jump the gap on a fouled plug  & the engine fires right up
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 21.03. 2019 19:23
Well that was a short lived success  *roll*

The A10 went brilliantly for a short run around the countryside yesterday. Started well, ticked over nicely and pulled great. Until I took it to work this morning. The bike suddenly stopped working 1km into my journey. I went around a roundabout and engine just conked out. No life in it again.

I've just pushed the motorcycle home and back to square one. I took the spark plug out of the cylinder and kicked the bike over. Have a good spark. I sprayed engine starter into the engine incase it was bad fuel...nothing again. I cannot understand this motorcycle one bit. Cracking the engima code couldn't been this hard  *lol*
Title: Re: Can ignition timing go faulty during use?
Post by: RDfella on 21.03. 2019 20:45
Presumably the good spark was after it had cooled down? In which case almost certainly a duff condenser in the mag. Unfortunately that means a rewound armature as it's in the centre (daft design). Not sure about the lates ones that fit at the points. Look a bit small to me, but maybe worth a try.
Title: Re: Can ignition timing go faulty during use?
Post by: berger on 21.03. 2019 22:49
RD fella many years ago mine had similar problems, had the mag re-wound with what I think he said were 2 modern condensers and if one packed up the other took over *dunno2* but also at this time it started banging in the exhausts and  missing then picking up ,after the mag was done I found out  the points  were toast as well. glad I had the mag done though it was  a 1960ish mag and still had original wrapping. I put the platinum tipped points on and jobs a gooden. it seems when owains is getting hot is when the problem starts which at first I would say condenser, in my case I don't know weather mine was points- condenser- or both at the same time
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 22.03. 2019 08:23
Hi Owain.  One more try.  Get yourself some plugs from a running engine. I re-read this thread and see you have new NGK plugs, which have (I understand) been the subject of counterfeit operations.  Maybe you got unlucky.

 Give the cylinders a good dose of fresh fuel down the plughole, then maggy end cover off, fuel off and get kicking with no choke, varying the throttle. It should fire and run for a couple of seconds. If successful, repeat with the fuel on and a bit of choke to keep it going.

 If it is still dead, time for another go at the magneto. This is still your number one suspect, reviewing this thread again from the start.

 If it will only run with continual priming down the plugholes, that suggests the carb is acting up. Try your old carb, cleaned and checked, the new one may be not as good as it could be. Check the fuel lines, just in case some sediment is being drawn down after your heroic test run.

 Once running OK cold, the classic symptoms of a failing condenser are  a reluctance to start when hot, and erratic running and sudden cutting out, again once hot. The condenser within the magneto is buried in the armature, at the drive end, where it is nice and warm.... they have a hard life.

 The Brightspark Magnetos Website will tell you all you need to know about why they fail and the simple effective options for a fix, essentially and very sensibly moving a modern type condenser to the points plate for easy access.

 If you go this route the existing armature does not need a rewind, just as long as it is electrically sound, and is used with a slight  circuit alteration to isolate the suspect condenser.  In the end the choice is yours, but for my money, conversion to an easily access  Brightspark condenser makes good sense if you are determined to retain a standard magneto.

 For a simple assessment of your magneto, I would recommend Priory Magnetos. Here bear in mind this is a small business, and opening hours and availability of service depend on existing workload, so best to make contact first by email via the website. If the armature turns out to be the problem, electronic ignition, typically Thorspark, is a good choice as it retains the defunct magneto  with ATD as a basic mounting and is fairly priced compared to a full house rebuild of your suspect magneto.


 Swarfy.
Title: Re: Can ignition timing go faulty during use?
Post by: RDfella on 22.03. 2019 12:05
Just to a add to my previous post - it's not unusual for condensers to be fine when cold but fail when they get warm. Trouble is new condensers will be of unknown quality and NOS are no better, because they can deteriorate with age. Wonderful.
Another thought - is Owain using suppressed plug caps? If so not only do they reduce the spark intensity, but they also cause a large rise in mag internal voltage - enough to make a mag fail. Have the test data on that somewhere and it's quite alarming.
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 04.05. 2019 20:29
UPDATE:
I've just received the magneto back again from the repairman. Symptoms are still the same though. I get a shock if I hold the ends of the HT cables and kick it over but I'm not getting any indicator of combustion.

I'll change the fuel tomorrow and buy new spark plugs to see if that fixes the problem. Although I can't help but think that there still is another underlying issue causing the ignition to fail. It just seems very odd for the motorcycle to start running again only to die on me the moment I go around a roundabout.
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 04.05. 2019 22:01
Owain
 Do the usual check of making sure the cylinder on compression has the pick up brush over the brass segment of the magneto slip ring, it's easy to swap the leads over by mistake.
 Does the magneto look as if anything has been done by your repairer? If it gives you shocks, back from being checked over I would expect it should give a bloody big spark in the open air. If this in order, another rough check of the timing may be worth doing.

  Leave the magneto cover off, it could be grounding somehow, through the kill button wiring.

  Give it a good dose of Start Yer Bas**d along with your new plugs. Just dropping the plug cap loosely onto the plug was an old trick to boost the spark enough to clear a fouled plug, as the spark jumped the gap between the plug and the cap as the engine vibrated. So try this, may be just the boost it needs to get it to fire up.

 Swarfy.

 
Title: Re: Can ignition timing go faulty during use?
Post by: duTch on 04.05. 2019 22:28

 
Quote
.....It just seems very odd for the motorcycle to start running again only to die on me the moment I go around a roundabout

 I don't recall that bit, but as suggested above, maybe there's something loose earthing it out, or *dunno* maybe if there's a wire to a handlebar cutout rubbing or pinching when you turn 
Title: Re: Can ignition timing go faulty during use?
Post by: ironhead on 05.05. 2019 12:02
UPDATE:
I've just received the magneto back again from the repairman. Symptoms are still the same though. I get a shock if I hold the ends of the HT cables and kick it over but I'm not getting any indicator of combustion.

Sounds like leaky HT leads and or Plug caps. If all is good you should be able to touch the plug caps with the engine running & not get a boot *eek*. Or are you sticking your finger where the the plug is supposed to go :o
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 05.05. 2019 17:00
Tried new NGK B6HS plugs today. No luck. I also tried a simple test: Spark plug tester connected to a plug cap with the other end grounded to the engine. When I get the the engine over the bulb lights up. When I introduce a new spark plug to the circuit and ground it to exactly the same point. The bulb does not light up and no spark can be seen.

I checked for a possible source of grounding but can't any and the above test seems to indicate that a unexpected ground isn't the issue. 
Title: Re: Can ignition timing go faulty during use?
Post by: RDfella on 05.05. 2019 20:07
Lets get back to basics here, or you'll be going round in circles. You say you get a shock from the ends of the HT leads. But that's no real indication. Need to hold the end of the HT lead about 8 - 10 mm away from bare metal and make sure you've got a fat blue spark. If no-one's around to help you to do that, open up the gap on an old spark plug and lay it on the cyl head and look for said blue spark.
Do you have a mag cutout on the bike - either on the mag or by wire to a kill button?
If no spark, have you tried it with the end cap off?
What condition are the mag pickups and HT cables?
Are HT cables wire core or carbon filament?
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 06.05. 2019 22:11
@RDFella Thanks for the tips. I have mag cutout on it and I removed it when kicking the bike over but had no effect. I couldn't get a spark to jump 8-10mm either from the HT lead to the engine either.

I took the magneto off the bike to test it to see if it's a bad ground (although I was trying to ground it directly to the mag before anyway). Long story short, the little process on the rear of the contact breaker assembly (that little bit that sits in the groove in the spindle) has broken off. Now I have to get another contact breaker assembly before continuing with this horrific problem that has been plaguing me.

Oh also, I bought new copper core HT cables and new NGK non-resistor type plugs. The mag pick-ups were replaced by the repairman and seem to be a pair new replacements for the originals.
Title: Re: Can ignition timing go faulty during use?
Post by: chaterlea25 on 06.05. 2019 22:39
Hi Owain
Surely the "repair man" should have looked and seen the contact breaker rotor problem??????
Is it a brass or steel points rotor?
A new "key" can be made and soldered into place Or
A competent repairer can press a new key 180 degree's opposite the missing one

 *conf2* *conf2* *conf2*
John
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 06.05. 2019 22:48
It's a brass one. I have a feeling that I may have broken it by over tightening the autoadvance bolt onto the mag spindle (maybe). I tried to solder a bit of flux myself but it doesn't want to bond to the brass (perhaps I'm using the wrong stuff). I also tried to 'build up' a little bit of material with my arc welder...in hindsite that was a foolish idea. :(
Title: Re: Can ignition timing go faulty during use?
Post by: groily on 07.05. 2019 07:09
The keys are fragile and if the cb unit has been shoved on out of alignment, the raised portion gets squashed when the centre screw is done up. Sometimes, it's missing altogether and there's just an open notch where the key used to be.
As Chaterlea says they can be reclaimed, or a new one formed exactly opposite - and they can also be repaired with solder if necessary. Fiddly job with swiss files etc after, but the brass will take it ok, and as the key shouldn't be doing any work beyond acting as a register, the thing ought to stay put, and survive.
Title: Re: Can ignition timing go faulty during use?
Post by: Swarfcut on 07.05. 2019 09:17
 Owain...    At last, a bit of good news.  A contributing fault identified and the answer to the title of this topic. YES IT CAN!

 By all accounts the magneto is generating sparks but not necessarily at the right time, and the reason why is now clear. Looking back at this saga, the answer was there from the start. 

 So for now I would clean up the mating surfaces, even a vestige of the key should be enough to locate it. If it is smoothed off completely try a small drilling and a soft brass or copper locating peg. Just big enough  to locate the plate, but not too big to bottom on the internal slot on the armature taper. As groily says, the drive is transmitted by the taper, and the bolt needs to be reasonably tight for the taper to grip, but not murder tight. Tapers too loosely tightened are the main cause of keyway damage and sheared keys, typically as seen on gearbox mainshaft/clutch centre tapers.

  Another problem may be that the internal taper on the armature has been spread, resulting in rock on the points plate, and consequent inconsistent points gap (and varied timing) between the cylinders.
   What I am suggesting is to reassemble with what you have to establish whether the magneto is capable of sparking at the right time, before spending more cash on what may prove to be a shagged  armature. A bit of a temporary and maybe unreliable fix, but to just get it running again. For future serious use I still consider a Thorspark System is your cheapest long term option. You may spend up to 25% of this cost just for a set of well used points on a questionable backing plate.

 Brass contact plates and later steel backed versions interchange, but each requires its own specific retaining bolt.

 Swarfy.

 
Title: Re: Can ignition timing go faulty during use?
Post by: duTch on 07.05. 2019 09:43

 Without going back to read the whole story, is it possible to try a known good maggie to see i how it goes ?
Title: Re: Can ignition timing go faulty during use?
Post by: groily on 07.05. 2019 14:50
To Swarfy's point, yes - it should be poss to get the cb on in pretty well the right spot even without a proper register, to see how it does, even if only temporarily.
If it was miles off position from the get-go, you'd have had no / very weak sparks because the internal timing won't tolerate a truly massive error. But if when freshly assembled all seemed well, and then it went off, could be the cb unit had gone walkabout from a correct starting position, and moved enough - within the capacity of the mag still to spark after a fashion - to mess up the ignition point.
Sounds as if you'd maybe get to happy if the keyway could be recreated by one of the methods mentioned  . . . worth a go, anyway.
Title: Re: Can ignition timing go faulty during use?
Post by: owain on 23.07. 2019 22:13
As a follow-up to all the advice given and all problems with ignition, the motorcycle has been running well again. APL magnetos were kind enough to replace the contact breaker assembly that after using fine grit sand paper to give the point a very thorough clean; the bike started straight away. It appears that my problem may have initially been due to dirty points on the magneto. Although they allowed for some electrical discharge from the spark (enough to light up my cheap spark plug indicator) the connection between the points wasn't good enough to allow enough voltage to jump the spark plug gap. As for the broken fin on the contact breaker assembly, it's difficult to know whether this was broken before hand contributed to my initial problems or whether it broke due to my heavy handedness. Either way, once it was replaced and magneto points cleaned it worked fine!

Huge thanks to everyone for their input!
Title: Re: Can ignition timing go faulty during use?
Post by: Greybeard on 24.07. 2019 10:13
Good news!