The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Mosin on 23.09. 2009 17:31
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Can I pick your brains guys?
My A7ss is running lovely (except perhaps for a little difficulty starting). But I am finding that the right hand side plug is sooting up to the point where the engine runs very lumpy and then drops to one cylinder after about twenty miles. If I take the plug out and clean it, off we go again. The left hand plug is consistantly in perfect condition.
So far, I have checked the points, plug gaps, replaced the complete HT leads on both sides including the plug caps and pick-ups and cleaned the inside ring of the magneto using a stick with a bit of rag soaked in petrol as described in Haynes. None of these seem to have made any difference.
Can anyone suggest anything else to try?
Thanks,
Simon
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How far up the insulator does the mixture ring go on the left (good) plug? It IS fuel fouling you're seeing, right? Sooty, not oily?
There has been some discussion about bias spacers on this forum, but the more likely culprit is the ignition bias suffered by an inconsistent point gap. This has also been discussed at length.
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What plug are you using, maybe a hotter plug would cure it.
All the best - Bill
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I am using NGK B7ES plugs on both sides.
I have just double checked the points and discovered that whilst the gap on one side is dead on at 12 thou, on the other side it is quite a bit wider. Does this sound like the cause of my sooting? If so, how do I go about changing the one side without adversely affecting the side that it set correctly?
Apologies for my unacceptable ignorance of what should really be the most rudimentary piece of schoolboy mechanics.
Simon
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Widening the gap will retard the ignition as it will take slightly longer for sufficient potential to build up to force a spark to jump the gap.
This will do either one of 2 things.
1) cause the spark to track down the side of a slightly contaminated insulator = miss.
or
2) cause a fouled plug to fire and eventually run clean.
Which way it goes in any particular cylinder seems to rely on Vodoo more than any combustion or engineering principles.
The only way to get plugs exactly the same is to use one of those plug testing machines which tests your plug under pressure but they are very hard to find now days as the plug companies stopped making them as they reduced new plug sales.
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one side is dead on at 12 thou, on the other side it is quite a bit wider
magneto points cam & timing, see http://www.a7a10.net/forum/index.php?topic=1375 & http://www.a7a10.net/forum/index.php?topic=1610.0
A little l\r difference in points opening gap should not affect spark strength in any big way, but timing may be off. Seems like your mag may need a tune-up, whatever the cause of the R cyl sooting.
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Actually, closing the points gap will retard the timing; one flat equals 2 degrees.
David
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Well today things have just gone from bad to worse. Or at least, to more confusing...
Last night I had a right good tinker with the points and got the gap on both sides as close as I possibly could. This morning she started second kick and after a few moments just running on one cylinder settled down nicely on two. I went for a ten mile run, stopping half way to fill up with petrol, after which she started first kick. All seemed well and she was actually running really nicely. I got home and figured I'd have a quick look to see if the r/h plug was sooty. It wasn't. 'Great' I thought, all sorted!
But alas no, When I tried the bike again a couple of hours later (after touching nothing else in the mean time) she fired just on the l/h cylinder. I set off, thinking that the r/h would kick in as thing warmed through. After a couple of hundred yards it was clear that this wasn't going to happen and I limped back home running just on the left hand side.
Much more tinkering with the plugs, points HT pickups etc and now I cannot get the bike to run at all. Grrr.
But the really weid thing is that I tried using an ignition tester on the r/h side and it is showing a very good spark between the ht lead and the plug, but this just doesn't seem to be igniting anything in the barrel. And equally crazily, my tester isn't showing me as having any spark at all on the l/h side regardless of what I do.
To say I am confused is an understatement.
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I think my next move would be to replace plug leads and caps
All the best - Bill
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I think my next move would be to replace plug leads and caps
All the best - Bill
I replaced them with brand new ones a couple of days ago. I also tested them for resistance at the same time and they showed up as having virtually none.
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In circumstances like this its time to go back to basics. Check and reset everything from scratch. Clean the mag ring, pick ups, refit the ht leads, new caps. new plugs, clean the points with a mag file and reset the gaps. If you do all that and still no spark, the mag must be duff. Its not something silly like a bad cut out button is it?
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I replaced them with brand new ones a couple of days ago. I also tested them for resistance at the same time and they showed up as having virtually none.
[/quote]
Was this after or before your troubles
All the best - Bill
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I replaced them with brand new ones a couple of days ago. I also tested them for resistance at the same time and they showed up as having virtually none.
Was this after or before your troubles
All the best - Bill
[/quote]
I've had it running well since replacing them.
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I would not use NGK plugs in any British bike. I have tried them and had nothing but trouble.
I stick to Champion.
Trev.
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Plug leads must either be solid copper, or spiral wound inductive type.
Normal car leads ( graphite powder in a fiberglass matrix ) will not work.
Even worse is that they will test ok and may even throw good sparks the when you get underway and vibrations start the graphite powder will shake away from the high points and the lead will go open circuit.
This applies to any and all graphite leads which includes Harley , BMW's or any other motorcycle branded leads.
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I have to agree with Trev regarding NGKs.
In my experience, when I had a duff mag that was killing plugs, I always got far further on Champions than an NGK... Only half a mile on NGKs once.
I think your problem is not just plugs though.
Do you have a local mate with a good running A10 ?
If so, see if you can borrow his leads (including pickups) and plugs, and try them out.
I know a lot of people have run into problems with new pick up brushes that are too soft as well.
Cheers,
Iain
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I've now swapped the leads over and the situation is still the same (no spark on lhs and spark but not even trying to fire on rhs). I even made up a new lead from some bits that I had kicking about and tried it on both sides with exactly the same results. I can only assume that the rhs is failing to spark under compression which is why it is not firing.
I guess that kind of rules out the problem being anything to do with either the plugs or the leads.
I cannot think of anything at all that I can do to the points that I haven't already tried, short of replacing them, so I have ordered a new set from C&D which should be here tomorrow. But if the plugs had burned out, why would I still be getting a spark on the rhs? Hmmmm.
Things are increasingly starting to look like the problem might be in the Magneto somewhere. And that sounds expensive.
Simon
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Ha ha! Fixed it!
It turns out that the rocker arm adjuster on the rhs inlet valve had worked itself so loose that it had actually allowed the rocker arm cup to jump off the top of the pushrod = no mixture getting into the cylinder = no firing. Persumably it beginning to work loose was also the cause of the plug fouling issue that started this thread.
I fixed this and re-set all the valve gaps and she started first kick! I tried again, this time with my ignition tester on the left cylinder and sure enough, it was now sparking!
It would appear that because of all the other things going on at the same time, I lost site of the wood for all the trees. The points were still badly pitted though, so with a new set fitted tomorrow I should be laughing. Until the next thing goes wrong that is!
Simon
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Hi Simon,
Good to hear that you found your problem (one of anyway *ex* *ex*)
If the points are pitting or burning it means the condenser (capacitor) is on the way out
Unlike others I am an NGK fan, if the bike is running properly they will last almost indefinitely, they dont like being oiled up tho, that said my MZ gave no bother for years on NGK's,
My wifes Mini has NGK's and the reccommended life is 60,000 Km
I changed them but could see very little difference between old and new *ex* *ex*
One word of warning though, DO NOT use plugs with an "R" in the code as these are resistor types
Cheers
John
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Just been for a ten mile run and while the rh cylinder is running lovely, the lh one is cutting in and out quite regularly, especially at lower revs. I have always had a weaker spark on the lhs, but this is getting annoying now. At first I thought that it might just be the new pickup bush taking a bit of time to bed in, but it doesn't seem to have got any better (or worse).
Given that I have now changed virtually everything in the system, I still seem to have this problem which has been with me since I bought the bike. What on earth could be causing a significantly weaker spark on one side than on the other?
If my problem is with the capacitor, can this be changed easily?
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Simon,
I don't think it can be the capacitor if only a problem on one side.
If you have not reviewed the following discussion, this might be a good time: http://www.a7a10.net/forum/index.php?topic=1258.0
One thing that sticks out in this topic is checking closely for cracks in slipring and pickups or other leakage paths between mag and spark plug.
Refreshing our collective memories, you only have one carb, right?
Richard L.
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I agree with Trevor, I have known these carbon leads to be faulty on cars (mine) but test ok, just moving a lead would have it working but once it settles back to it's in situ position it would cause misfires, took ages to track down as a fault.
Of course maybe you have'nt used this type.
Shortly I will be wiring up my refurbished 12 volt converted dynamo and solid state regulator so your problem is of great interest to me. hope you get to the bottom of it soon
All the best - Bill
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Carbon leads are a pile of manure, throw them away and get copper wire ones.
I would not use NGK plugs in any British bike. I have tried them and had nothing but trouble.
I stick to Champion.
Its funny how we all have different experiences, I had NGK plugs in my A10, when I rebuilt the engine I fitted new Champions, one failed after about 50 miles or 3-4 heat cycles, went back to NGK and no more probs.
ps, Her indoors is at work in the morning, the forecast is good so the plan is to do some serious miles up in the Cotswolds... Bring it on..
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My HT leads are just ordinary copper core, bought by the foot from my local bike shop.
And yes Richard, I am just running the one carb.
Given that I have now replaced, swapped or exchanged everything beyond the Mag, by my reconing the problem must be something to do with what happens to the spark before it hits the HT lead pickups. Tomorrow I will replace the points. If that doesn't fix it, then that only really leaves the Mag itelf. But frankly, I wouldn't have thought it possible to have one side sparking noticably more powerfully than the other with all other things being equal.
The only other thing I can think of is that I have used quite a bit of "Holt's Damp Start" on the caps/leads etc. I wouldn't have thought that this could cause me any problems with conductivity, but maybe I am wrong.
All I want to do is ride the bloody thing..... :(
Simon
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Simon,
I hear you. When you find the actual cause, we are all going to feel like "gee, why the hell didn't I think of that!" Keep trying. It will be worth the effort and make the ultimate hard-earned riding all the sweeter.
I really don't know what affect the "Damp Start" might have, but wiping everything down to nice and clean, including the slipring (maybe, using some alcohol) and, while at it, taking another look at the condition of the pickup caps, is a reasonable next (or repeated) step. One of the frustration stories that has been told here ends with the owner finding a hairline crack in the pickup cap with the spark tracking through the crack out of view of casual observation. I'm not going back to re-read the whole thread. I think you tried swapping leads with same result, but can't recall.
I admit to grasping at straws here, maybe more than anyone, and I don't want to cause you unnecessary mess-around labor that doesn't lead to an answer. However, I wonder if it would be informative to reverse the timing of the mag so that the lobe now firing left becomes the lobe firing right. The one thing that I think this could show would be if there is a flaw in the slipring, but it may be another goose chase, so, proceed at your own risk of frustration.
I hope that having the advice and guesswork still pouring in is useful to you. Maybe something will trigger the spark (so to speak) in your head, that finds the trigger for the spark in your left cylinder.
Richard L.
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I have been following this thread for a couple of days and I think Richard, (manasound) has some good advice as it is not unusual for the point gap to be different on each ramp of the cam ring, worth a check when you fit the points, if that is the case then it looks like another dremmal job!.I wish you all the best with it
Richard
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Simon,
I just re-read my last post and I thought there might be some misunderstanding. When I said "I'm not going back to re-read the whole thread," I meant that I had not checked to see if you had already tried swapping your leads to determine if the problem followed the leads or the followed the mag.
Just thought I'd better try to be clear, at the risk of adding to the confusion.
Richard L.
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Have you swapped pick-ups?
Richard
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Yes, I did mean leads and pickups, and Richard (Orabanda) is quite right in correcting my shortcoming of detail. Thank you, kindly, Richard.
Richard L.
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Forgive me if this suggestion has already been made. Have swapped the plugs over? You might just have an intermittent fault with the plug. I have had similar symptoms in the past due to plugs breaking down when they get warmed up. I have no idea what causes this, but by the simple expedient of changing a plug the problem has been resolved. I once fitted a set of new plugs to my car and the complete set was faulty. I only found this out after I had changed everything else on the ignition system. The engine would rev it's head off until it was under load, then it would miss and not pull. What this proves is that just because something is new there is no absolute guarantee that it is serviceable. The other thing that occurs to me is this: when you swapped your leads over did you swap the pick ups and brushes over or did you unscrew the leads and swap them. It could be the case that you have a weak spring and that the brush is intermittently loosing contact with the slip ring. On a general comment relating to uneven plug colours, this seems to be an on going problem with A10s, and there numerous causes, anything from uneven timing due the cam being not exactly 180 degrees apart to subtle differences between the head geometry. Even when the points have a 12 thou gap on both cylinders it does not mean that they are opening at the same point, and if one cylinder is more advanced than the other the retarded cylinder will appear to run richer. There are so many variables, and they can prove to be very elusive. Good luck in your endeavors to sort your bike out. For the record I have spent the morning trying to extract a piece of inner cable from my rev counter after it sheared inside the drive head. Nothing it seems comes easy.
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Yes, wise words A101960.
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I would not use NGK plugs in any British bike. I have tried them and had nothing but trouble.
I stick to Champion.
Its funny how we all have different experiences, I had NGK plugs in my A10, when I rebuilt the engine I fitted new Champions, one failed after about 50 miles or 3-4 heat cycles, went back to NGK and no more probs.
ps, Her indoors is at work in the morning, the forecast is good so the plan is to do some serious miles up in the Cotswolds... Bring it on..
And what happened, started her up, warming on the drive while I was putting my helmet on and suddenly stops firing on RH cylinder, -- lovely new NGK failed. *conf*
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My 1960 A10 G.Flash is suffering from exactly the same symptoms. It was running well, back in 1966 when I put it into retirement. Brought out from its sleep recently,after a bit of fettling it started 3rd kick! However a short trip down the road and it was mis-firing with the plugs sooting up. Carb.seems O.K. Timing has never been interfered with. I have spoken to Gary at SRM and he is convinced that after all these years the condenser is the most likely culprit, so thats my next step.
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About 20 years ago I restored a Triumph twin ( first and last one I have owned) and when I got it the maggy looked perfect. The insulation was rock hard on the armature and it threw a very good spark so I put it on the bike. First ride after about 50 miles the armature melted stripping the drive gear and I had to walk home, not impressed ! Its not easy getting a melted armature out of a maggy body either.
Anyway to get to the point, since then every bike I have owned the very first thing I do even if its supposedly a brand new maggy is to get the armature rewound and the body remagnetised if necessary. I am lucky to have a very good magneto specialist to do the armatures. Use only solid copper wire and the best caps money can buy. Do not buy cheap pickups, get them from a reputable supplier, those plastic hexagonal ones you see are utter rubbish.
Since I have been doing this I have never had a failure and all my bikes are one kick starters.
On the subject of plugs, I have used NGK's for nearly forty years now and have always sworn by then but over the last five years or so I have had a few fail. One would not spark at all brand new out of the box. I wonder if they are manufactured under license in Taiwan (my apologies if there are any Taiwanese reading this) or somewhere and the quality has gone downhill in recent years. I used to use Golden Lodge's in my race bikes in the early seventies, anyone remember them?
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As to the origin of NGKs, I don't know if it's true, but I was told recently that they are made in Japan and in France. The Japanese ones apparently are better. Why am I not surprised?
I have been using them for years too, but have come across a couple of dodgy ones, like Brian, in the recent past. However, the B6HS's (I think) in my A have done best part of 25000km and are good as ever, I've successfully run B7ES and B8ES in other twins for ages, and find BP6's (with the sticky-out nose but never with an R in) good in another beast.
Friends with other marques have had a few probs with NGKs from whichever source, however, and their name is mud thereabouts. But they are easily available over every counter . . .
To be safe I carry Champions in the toolboxes just in case . . . . but to be fair I have had dodgy Champions too over the years.
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and they call lucas the prince of darkness *smile*
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Well, to bring things up to date, I have finally got my bike running again. I think the problem was that the original left hand mag picup was U/S and the replacement part which I bought was also faulty. Eventually I got hold of a third pickup, cleaned it meticulously with petrol and a small artist's paintbrush and left it to dry out for a couple of days before fitting a brand new brush and reconnecting the original lead/plug cap. Result: it fired immediately!
I have now covered about 30 miles on it and to my frustration, I am exactly back where I was three pages of posts ago. The l/h cylinder is running fine but the right hand one is sooting up again.
Grrrrrrr.
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By "sooting," I am assuming you mean completely dry and dusty black; no wet oil or odor of gasoline on the plug; still firing on two cylinders the entire 30 miles; left plug is a delicious chocolate brown. If all these are true, then, by the education granted to me at the The A7/A10 Forum University, I must assume that your problem is induction bias, to be cured by a wedged-shaped gasket fitted between drip pan and head and causing the carb to angle toward the left cylinder. If, after this, both sides are equally a bit sooty, then, mixture is too rich.
As an undergrad, I welcome any correction from faculty.
Richard L.
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The head of the r/h plug is sooty and dry. There is a bit of oily wetness on the threads. and it seems to be missfiring intermittantly. This seems to be worse at low revs, but I might just be imagining it. Because the problem is not there all the time, it is quite difficult to diagnose accurately, and I am cautious that I may be desctibing symptoms of a totally different problem which are just making the original issue!
I have a 20 mile run home from work today and when I get there I will take both the plugs out and get some photos so people can see what they think. That might be easiest!
Simon
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OK, I took advantage of the unseasonably nice weather and had a really good run home from work today (about 30 miles). For the most part, the bike ran absolutely fine with only a few blips. On checking the plugs, I found that while the right one was a bit sootier than the left, it wasn't too bad and the electrodes were both clean. This set me a wonderin'...
The symptoms I have been experiencing were a sudden loss of power, particularly when the engine was running at low revs or ticking over, or if I had just closer the throttle having rounded a corner or something. This loss of power usually lasts somewhere between one and ten seconds before full power is returned. However, I discovered that by pulling in the clutch and giving the engine a quick rev, this would usually return me to full power immediately.
I have always associated these types of symptoms with the bike failing on one cylinder, but the nature of this power failure coupled with the engine's tendancy to return full power at higher revs has made me question whether I might be barking up the wrong tree altogether. Rather than being a total temporary ignition failure on one side, could my problem possibly be something to do with the auto advance unit sticking?
Simon