Plug Fouling

[tombeau]

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

[Mosin]

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

[Mosin]

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

[chaterlea25]

Hi Simon,
Good to hear that you found your problem (one of anyway )
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
One word of warning though, DO NOT use plugs with an "R" in the code as these are resistor types

Cheers
John

[Mosin]

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?

[RichardL]

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.

[bsa-bill]

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

[A10Boy]

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..

[Mosin]

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

[RichardL]

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.

[Richard]

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

[RichardL]

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. 

[orabanda]

Have you swapped pick-ups?
Richard

[RichardL]

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.

[a101960]

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.