The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: wortluck on 14.04. 2018 18:12

Title: Help - bike's gone bang!
Post by: wortluck on 14.04. 2018 18:12
Returning home today after a 100m ride when bike started popping, banging (misfiring) then packed up.  Tried to kick it a couple of times but just popped and banged.  Checked plugs - fine with good spark.  Checked points - all good.  There is a bit of oil in the left hand silencer - right hand silencer is nice and dry.  What do you reckon - could it be a valve problem (broken spring, for example)?  Any help to diagnose would be much appreciated so I can get back out on the road asap.

Cheers in advance!!
Title: Re: Help - bike's gone bang!
Post by: Billybream on 14.04. 2018 18:32
Could it be stale fuel, on my first ride out after winter lay up never seems to run very well until the tank is refreshed.
Title: Re: Help - bike's gone bang!
Post by: a101960 on 14.04. 2018 18:39
Quote
Checked points - all good.
Sorry to hear about your problem. I had a similar breakdown a few years back and in my case it was caused by one of the points faces falling off. I am not sure how they are held in place (welded) I suspect. Anyway at first glance everything looked to be O.K. I could see nothing wrong. The points even appeared to be opening and closing, and it was not until I started to remove the points plate that I noticed the point face lying on the cam ring. I replaced the points and the engine started right up. The symptoms I had though, exactly matched yours. Not saying that is your problem, but it s worth checking. The sliver of metal that makes up the point face is very thin and small which is why I probably did not notice anything being amiss, because everything looked O.K.
John
Title: Re: Help - bike's gone bang!
Post by: wortluck on 14.04. 2018 18:47
Thanks for your speedy replies!!

Fuel - I had half a tank of old fuel but it was sealed (taps off and tape put over fuel cap breather) to try to keep it as fresh as possible.  Bike was a bit sluggish but I burnt off 50 miles of it before refreshing with super unleaded - then went the other 50 miles really nicely.

Points - this is a good point (pun not really intended!?).  However, would the plugs not spark if the points face had fallen off?  Spark did seem quite healthy on both pots.  Will look at them a bit more closely though as the checks were done roadside.

Cheers again guys.
Title: Re: Help - bike's gone bang!
Post by: a101960 on 14.04. 2018 19:14
Quote
Will look at them a bit more closely though as the checks were done roadside.
Yes that's where I checked mine at the side of the road. It was not until I got the bike back home that I noticed what had happened. The facing is very small so would not be easily noticed. It is always possible I suppose that the timing has slipped, not very likely I know, but it is possible.
Title: Re: Help - bike's gone bang!
Post by: wortluck on 14.04. 2018 19:30
Could you tell me how the timing could slip.  I've never had this on any vehicle I've ever owned, so would need some pointers (another bad pun, sorry)
Title: Re: Help - bike's gone bang!
Post by: duTch on 14.04. 2018 19:41
 
Quote
Help - bike's gone bang!

 That sounded like the piston was coming up to say hello... *eek*

 
Quote
Could you tell me how the timing could slip.  I've never had this on any vehicle I've ever owned, so would need some pointers (another bad pun, sorry)

   It could slip if the nut was not done up on the pinion. (They don't need to be super tight though)

 Maybe check the carby for loose jets or blockages....I think a loose or dropped main jet could have those symptoms. The other week after I'd had my Gutzzi apart, I discovered the needle clip had somehow dislodged and the needle was stuck protruding up out of the slide - that made it run uneven...... *conf2

Title: Re: Help - bike's gone bang!
Post by: a101960 on 14.04. 2018 20:08
Quote
Could you tell me how the timing could slip.
Not a common occurance, but it has been known to happen. The pinion relies  on a tapered shaft to keep everything tight and it is clamped into position when its all tightened up. I am sure you have heard or read about the pinion slipping during the tightening up process when the ignition is being timed. Occasionally the pinion will slip spontaneously for no apparent reason under normal running conditions. Somehow the pinion manages to become loose. As Dutch has said maybe the nut was loose or perhaps it could have backed off a bit. Something else has just crossed my mind. It could be that a push rod has jumped ship. It does not happen often, but once again it is not unknown.
Title: Re: Help - bike's gone bang!
Post by: berger on 14.04. 2018 20:20
I have not been to the pub, don't know about the oil bit but when mine had symptoms like that it was condenser breaking down under load. off to pub tmow
Title: Re: Help - bike's gone bang!
Post by: wortluck on 14.04. 2018 20:39
Thanks for all the suggestions fellas!

Tried to kick it over this evening when it was nice and cool.  One big pop/bang/ then nothing at all.  Compression seems fine.

Would the pushrod try and make its way out of the engine?  If so, non have appeared.

Carb was brand new, but will check it anyway.

Timing is an interesting one.  Can totally see how this would screw things up but not so sure how its happened.

I guess its time to start taking things apart and having a look.  Just a git how it's on its first run of the 'summer'.

Let me know if you have any more thoughts.

Will keep you updated!

Title: Re: Help - bike's gone bang!
Post by: morris on 14.04. 2018 20:58
Carbon traces from the brushes on the slipring can cause similar
Title: Re: Help - bike's gone bang!
Post by: wortluck on 14.04. 2018 21:01
Cheers morris, but would that stop the bike starting altogether?
Title: Re: Help - bike's gone bang!
Post by: morris on 14.04. 2018 21:24
Cheers morris, but would that stop the bike starting altogether?
Yep. Mine did. It’ll arc round the slipring and the spark then goes to both plugs at the same time.
At the plug it will show a good spark though.
I remember when trying to start it popped and banged but wouldn’t run.
When checking the spark at the plug, I accidentally forgot to put one of the caps back on and miraculously, on the next attempt it started to run on one cylinder.
But as soon as I put the cap back on it died and refused to start again.
Title: Re: Help - bike's gone bang!
Post by: wortluck on 14.04. 2018 21:29
Thanks morris.  Presumably giving the slip ring a really good clean then applying a light touch of oil again will be the way forward.  Might even try removing one of the plugs and see if it fires.
Title: Re: Help - bike's gone bang!
Post by: duTch on 14.04. 2018 21:38

 
Quote
Presumably giving the slip ring a really good clean then applying a light touch of oil ...........

  *????*
 
Title: Re: Help - bike's gone bang!
Post by: wortluck on 14.04. 2018 21:42
Sorry duTch, too much ale!  Any tips on how to clean the slipring, or check its condition, or diagnose if it's that that's causing the problem?
Title: Re: Help - bike's gone bang!
Post by: morris on 14.04. 2018 21:54
Take the brush off and have a peek in the hole. If there’s a carbon trace it should be visible and/or can be felt with your finger
Title: Re: Help - bike's gone bang!
Post by: duTch on 14.04. 2018 22:00
 
Quote
Sorry duTch, too much ale! ......
      making me look good  *smile*

 
Quote
......... Any tips on how to clean the slipring, or check its condition, or diagnose if it's that that's causing the problem?

 A small round mirror and bright light is handy for close look; to clean I just use some metho on a rag and poke that in (one of) the pickup holes with a stiff middle finger- can be a bit fiddly... and crank it over *slowly* (lessens chance of a whack if no kill-switch) Do all the brushes also, not forgetting the Earth brush at drive end.

 Brake or Carby cleaner may work too, but unsure of compatibility with bits.
Title: Re: Help - bike's gone bang!
Post by: chaterlea25 on 14.04. 2018 22:00
Hi,
As Morris found out try starting the bike with one plug lead disconnected (the same happened to my bike some years ago *sad2*)
Next,
I would check the timing, maybe the mag tufnol gear has failed?
Next,
Check the valve clearances, you might have sticky valves??
If the tank has sealer in it it can dissolve into the fuel and cause sticky valves *ex* What a PITA  *angry* *problem*
When you have the rocker covers off check with a suitable lever /screwdriver that the pressure to open each valve is the same ( I once got an A10 in with a very soft valve spring)

John
Title: Re: Help - bike's gone bang!
Post by: duTch on 14.04. 2018 22:26

 You may or not also have another earth brush behind the points plate (CB Plate), my magneto has both but I'm not sure if they all do.

 Just remembered when my maggie died last year, it fired up fine as normal to go to work, then cut out one side but came back intermittently but finally died completely after 1 or 2 Km's ( 'dead' = burned windings & dud condensors)
Title: Re: Help - bike's gone bang!
Post by: wortluck on 15.04. 2018 08:14
Morning all, up bright and early to start investigating.  *conf*

Thanks for all your suggestions - really helpful!!  I suppose that the method of starting with the simplest is the way forward.  Just a PITA that it's just before a half decent week of weather in the UK (rare) when we could be hitting 20C (heatwave). *cry*

To my chagrin, I have to confess (duTch) that my terminology and knowledge isn't as good as all yours when it comes to Brit bikes (slipring gaffe), *respect* as this is really the first one I've owned apart from a brief flirtation with a B31.  As a kid, it was all 70s and 80s japanese bikes apart from a 1959 R60 BMW which was found in a chicken shed and restored by myself. 

A good soaking in ale complicates things even further. *beer*

Thanks for you patience!
Title: Re: Help - bike's gone bang!
Post by: duTch on 15.04. 2018 11:08

 hmmm....not sure what to make of that ^^ I try not to do doubledutch, but sometimes it just happens *conf2*  let me know which bits are messing you up ??

 PS ;
Quote
*respect*
..while you down there...nah just jokes....get up and face the day.... *smile*
Title: Re: Help - bike's gone bang!
Post by: wortluck on 15.04. 2018 12:41
You posted a  *????* when I mentioned putting a dab of oil on the slipring.  *eek* What I was getting confused with was the ring where the points sit (the ring with raised bits to open the points).  There, you can see how thick I am.  Was hoping to avoid some of the humiliation but your saucy comment has helped dash any hope I had of that. ;D
Title: Re: Help - bike's gone bang!
Post by: bsa-bill on 15.04. 2018 12:56
Quote
Was hoping to avoid some of the humiliation

Like many here I've spent 74 years trying to avoid humiliating myself, not quite there yet but getting a tad better .
No worries it's all worth it when you get out and about on an A and see the admiring glances, oh and that would be the camring
Title: Re: Help - bike's gone bang!
Post by: wortluck on 15.04. 2018 13:14
Thanks Bill, my mental health has now improved after that nasty-wasty wikked duTch said howwible fings. *sad*

Camring - of course - after drowning my sorrows with copious amounts of Tetley's Smoothflow, my brain departed to Never Never Land. *dribble*

You're right about getting out on the A. Only told wifey I'd be going for a quick jaunt to blow the cobwebs off and ended up all over the Peaks (down Woodhead Pass and back across Snake Pass) - absolutely brilliant! *wink2*

Just to complete my humiliation, by the way, I broke down about a mile from home.  Knowing Mr Breakdown wouldn't recover me so close to home, I pushed the (Better Shoved Along) back home - damn near killed me especially as some of it is uphill. *red*  It was also at the warmest bit of the day in T-shirt, fleece and jacket, so I was dripping when I got in.  I'm sure I saw a few grins as I pushed it forlornly through the town centre.  *roll* At one point, a guy came out of his house and helped me - probably though it was that or an ambulance. :o  The joys of owning a Beezer eh.

Title: Re: Help - bike's gone bang!
Post by: duTch on 15.04. 2018 13:28
 Above all- *don't* panic...we here to help each other......and have fun
   
Quote
.....when I mentioned putting a dab of oil on the slipring.  *eek* What I was getting confused with was the ring where the points sit (the ring with raised bits to open the points)........
  Had a feeling th's what you meant, as B-Bill says it's the 'Cam-ring' that opens the points, the Slip-ring is under the pickups at the other end of the plug leads from  *????*  yep the spark plugs *smile*

 
Quote
Quote.... Was hoping to avoid some of the humiliation ...

 I'm a bit different in that I guess I make a point of self-humiliation and get in first to steal the thunder of those that like to burn others... then it's all skyward...

A bit off topic, but it's often difficult to determine where each of us is at, because not just here, but in the big world we're all encouraged to 'sell' ourselves as big as possible; like with resumes/CV's, we're expected to embellish the facts with bullshit- I don't come at that at all....feel free to tell it like it is. I stuff up a bit most days ('no-not that left, the other left') *smile*

edit-rounded me up...
 
Quote
Thanks Bill, my mental health has now improved after that nasty-wasty wikked duTch said howwible fings. *sad*   

 Ok daffy- dat gave me a belly good belly laff  *smile*... too bad I just ran out of  *beer* *beer*
 
Title: Re: Help - bike's gone bang!
Post by: jachenbach on 15.04. 2018 13:40
Best to systematically troubleshoot. You say compression "seems good"? Check it and know for sure. If good, move on to ignition timing, spark quality etc. Finally carburetion. Going helter skelter from this to that is generally time wasted. I'm not saying not to check the obvious first. I've had bikes brought in to the shop due to being out of gas! All the above suggestions are possibilities, and I agree that ignition is the most common ailment on most any engines I've ever worked on, but diagnosis is a process best done in a linear fashion.
Title: Re: Help - bike's gone bang!
Post by: Triton Thrasher on 15.04. 2018 13:50
Clean the points.  Check the points gap and the ignition timing. 

Do it now!


Yes, clean the slip ring.  It is not the cam ring.
Title: Re: Help - bike's gone bang!
Post by: duTch on 15.04. 2018 13:56

 ...and don't forget that some symptoms that suggest a fuel/carby thing often turn out to be ignition...conversely things that (do I need to say it?)...show symptoms of Ignition related turn out to be fuel/carby issues
Title: Re: Help - bike's gone bang!
Post by: wortluck on 15.04. 2018 15:47
It's ok duTch, I'm with you with the bull&^%$ thing. When it comes to the world and all the carp in it, I'd rather be on the bike giving a metaphorical two fingers to all the nanny-state, snowflaky, pc, brigade that blindly follow all the other sheep in believing what they're told. Don't worry (sure you won't mate), I work in a secondary school with teenagers with behavioural issues - you soon grow a very thick skin very quickly!

RIGHT - have checked the SLIPRING and a curious thing happened.  As I did what was suggested and put a clean rag with meths on to clean it with my finger (did have a bit of carbon deposit on), turning the rear wheel in fourth no plugs, I found I could actually STOP the slipring from turning just with my finger in the hole (easy duTch).  There was also a bit of vibration which felt like a gear wasn't engaging properly (like when your bike chain used to come off or you've not engaged a gear fully).  I'm pretty sure this shouldn't happen as the slipring needs to be turning constantly.  I'm also guessing that if I've stripped something and it's not turning properly, all my timing will be out as well.

If I'm right, does sound a bit like a s**t load of money to get something rebuilt.  I tried to include some photos of the slipring which also shows what looks like a bit of a chunk out of the right hand side?  Files are too big to upload apparently??
Title: Re: Help - bike's gone bang!
Post by: harvey mushman on 15.04. 2018 17:43
If the slipring is running loose on magneto shaft the wire connection on slipring may also be disconnected, sounds like a magneto strip job!

Hope that helps   ;)

derek
Title: Re: Help - bike's gone bang!
Post by: wortluck on 15.04. 2018 17:58
Thanks Derek.  The slipping of the slipring is intermittent but definitely happening.  I even took of the mag cover to the points and observed it not going round as it should.  I'm still getting sparks, but I fear that my mag is goosed.  Next question is if anyone can recommend a good company for a complete strip and rebuild.  May be a stupid question but I'm guessing my timing is now all over the place??
Title: Re: Help - bike's gone bang!
Post by: Ted_Flash on 15.04. 2018 18:11
Stripped fibre timing pinion (on the Auto advance) - sometimes turning the magneto, sometimes not?
Title: Re: Help - bike's gone bang!
Post by: Triton Thrasher on 15.04. 2018 18:29
Ted’s got a good idea there.

Is it the entire armature that is not turning?  If the points don’t rotate, then that is the case.

That will be a stripped fibre pinion or the auto advance or solid pinion is loose on the tapered end of the armature shaft.
Title: Re: Help - bike's gone bang!
Post by: wortluck on 15.04. 2018 18:46
I think you may have it there guys!  The points rotate intermittently so it is the armature.  Is this a common thing?  Also, as I'm fairly new to Brit bikes, could you take me through the repair.  Presumably it'll need to be retimed - can I do this without specialist tools? I have an engineer pal who restores bikes so he may well be able to give some pointers (there I go again) or help out with tools.
Title: Re: Help - bike's gone bang!
Post by: Ted_Flash on 15.04. 2018 19:01
Priory Magnetos site has a brilliant document going through repairing an ATD - presumably also they can supply the parts needed.

https://sites.google.com/site/priorymagnetos/tech-tips-1
Title: Re: Help - bike's gone bang!
Post by: wortluck on 15.04. 2018 19:09
Thanks Ted, will check it out.  Many thanks for pinpointing what I reckon is the problem.
Title: Re: Help - bike's gone bang!
Post by: wortluck on 15.04. 2018 20:40
Picture of slipring!
Title: Re: Help - bike's gone bang!
Post by: chaterlea25 on 15.04. 2018 20:52
Hi Wortluck,

From my reply earlier
Quote
Next,
I would check the timing, maybe the mag tufnol gear has failed?

If the auto advance unit comes undone from the taper with the self extracting bolt, the job is  straight forward
Make sure to clean out the remains of the fibre gear teeth, change the oil, clean the sump filter + clean the oil tank out

John
Title: Re: Help - bike's gone bang!
Post by: morris on 15.04. 2018 20:55
I think you may have it there guys!  The points rotate intermittently so it is the armature.  Is this a common thing?  Also, as I'm fairly new to Brit bikes, could you take me through the repair.  Presumably it'll need to be retimed - can I do this without specialist tools? I have an engineer pal who restores bikes so he may well be able to give some pointers (there I go again) or help out with tools.
Start by taking the timing cover off. That’ll show whether the ATD pinion just came loose or (worse) the teeth have stripped.
For timing you won’t need any special tools apart from a timing disc. It can be done with the pencil down the plug hole trick, but a timing disc is more precise.
If the ATD came loose then you’d have to determine top dead centre on the right hand cylinder’s compression stroke. You’re on compression stroke when both valves are closed.
On the magneto side, you’re on the right hand cylinder spark when the brass part of the slipring is visible through the upper pick up brush hole.
Once determined those, find the exact top dead centre, fix the timing disc and create a pointer to the 0 degree on the disc.
Jam the ATD on full advance with a small wedge.
Then turn the cranck backwards by 32 degrees, put a fag paper between the magneto points and rotate the shaft (should only be a little bit) until the fag paper pulls out.
Thighten the ATD ( only slightly because you may need to loosen it again when the first attempt wasn’t entirely correct).
Once happy with the adjustment, tighten it up firmly, and you should have a working bike again
*beer*
Title: Re: Help - bike's gone bang!
Post by: KiwiGF on 15.04. 2018 21:04
Picture of slipring!

Although the slip ring is damaged it may not cause any problems, especially as the bike was running ok. They are not TOO hard (or expensive) to replace (I’ve done it myself, after making a special bearing removal tool) but you may want to get it done by a mag expert.

The slip ring damage was probably caused by someone attempting to remove the mag armature without first removing the screws that earth the HT when there are no HT leads fitted. I forget what those screws are called.....but it’s easy to forget to remove them and as they stick out into the space between slip ring “flanges” they can easily damage the slip ring, which goes very brittle with age.

As to the armature moving when it should not , you need to remove the timing cover and have a look at what’s going on, as per other posts it may just be normal movement from an auto advance unit, or a stripped fibre gear., or simply the mag pinion has come loose.

This does not sound expensive to me, just annoying!

Title: Re: Help - bike's gone bang!
Post by: wortluck on 15.04. 2018 21:20
Brilliant, thanks guys, but why change the oil and clean the tank and filter. Can debris get into the oil from where the ATD is (I changed the oil just before taking it out!).
Title: Re: Help - bike's gone bang!
Post by: morris on 15.04. 2018 21:38
Brilliant, thanks guys, but why change the oil and clean the tank and filter. Can debris get into the oil from where the ATD is (I changed the oil just before taking it out!).
Yes.
Have a recipient ready underneath when you take the timing cover off.
There’s quite a lot of oil in there.
It lubricates the cam and ATD gears.
Debris from the ATD gear won’t do much harm by itself, but may choke some small oil passageways... *eek*
Title: Re: Help - bike's gone bang!
Post by: Triton Thrasher on 16.04. 2018 07:01
I’d leave that chipped slip ring alone and just fix the magneto drive problem.
Title: Re: Help - bike's gone bang!
Post by: wortluck on 16.04. 2018 07:12
Don't worry mate, the mag was working fine and still gives a solid spark.  My philosophy, 'If it ain't broke .......'.  Just want to get the ol' girl back on the road asap - winter's for fixing things, summers for riding!
Title: Re: Help - bike's gone bang!
Post by: chaterlea25 on 16.04. 2018 13:44
Hi
Oil is cheap compared to engine rebuilds *warn*

John
Title: Re: Help - bike's gone bang!
Post by: wortluck on 16.04. 2018 18:10
UPDATE - Removed timing cover and ATD - half the teeth were missing from the fibre drive.  Thanks for pinpointing the problem.  I have the info to replace the drive but not really the time.  However, my engineer mate will help out if I can get a drive.  He says I need to get a Tufnol fibre drive and not plastic (didn't thing there were plastic ones out there and I'm not that daft).  However, can anyone recommend a supplier.  Have seen some on Ebay on sale from£12 to £22 which state they are fibre replacements - what do you reckon?

Because the tiny amount of debris in the timing chest doesn't correspond at all with the volume of missing teeth, it does like I'll have to change the oil and clean sump gauze, tank, etc.  I'm told that any debris should have made it to the gauze or to the filter/bottom of the oil tank.  I guess there's not much else to do if bits are still in the engine (shouldn't be much as the bike packed up pretty damn quick).

Someone did mention an ally drive, but I think these are for the manual A/R only.  Happy to stick with fibre.  Any reasons, apart from age, why the teeth stripped?  Mag turns freely!

Cheers again all!
Title: Re: Help - bike's gone bang!
Post by: Triton Thrasher on 16.04. 2018 18:46
Likely there was too much pressure put on the teeth last time the nut was tightened up.

I stick a screwdriver through the ATD yoke to push back against the spanner turning the the nut, to avoid straining the fibre teeth.
Title: Re: Help - bike's gone bang!
Post by: Greybeard on 16.04. 2018 19:00
...can anyone recommend a supplier.
Priory Magnetos. https://sites.google.com/site/priorymagnetos/magneto-atd-spares

In case you do not know; Priory is run by Andrew Guttmann alias Beezermac, Resident Legend of this forum.
Title: Re: Help - bike's gone bang!
Post by: wortluck on 16.04. 2018 21:14
In case you do not know; Priory is run by Andrew Guttmann alias Beezermac, Resident Legend of this forum.

No, I didn't know that.  Priory is excellent!

Actually found a lot more debris at the bottom of the timing chest underneath the *oil pump*?  Still doesn't account for all the missing teeth though.

What about the drive gear - any suggestions as to supplier.  Will ensure I don't put pressure on the fibre teeth.  Incidentally, the self-extracting bolt holding the unit on wasn't tight at all - is there a recommended torque or is it a nip up job.

Finally, a stupid question to many.  When timing it up with the r/h pot at TDC, I turn the crank back 32 degrees - is 'back' anti-clockwise as I look at the timing cover?

Cheers again.
Title: Re: Help - bike's gone bang!
Post by: Greybeard on 16.04. 2018 21:22
Finally, a stupid question to many.  When timing it up with the r/h pot at TDC, I turn the crank back 32 degrees - is 'back' anti-clockwise as I look at the timing cover?
Plugs out, bike in fourth, on the centre stand. You can easily turn the engine forward or backward using the back wheel.

Andrew may be able to help with the timing gears.
Title: Re: Help - bike's gone bang!
Post by: KiwiGF on 16.04. 2018 21:25
In case you do not know; Priory is run by Andrew Guttmann alias Beezermac, Resident Legend of this forum.

No, I didn't know that.  Priory is excellent!

Actually found a lot more debris at the bottom of the timing chest underneath the *oil pump*?  Still doesn't account for all the missing teeth though.

What about the drive gear - any suggestions as to supplier.  Will ensure I don't put pressure on the fibre teeth.  Incidentally, the self-extracting bolt holding the unit on wasn't tight at all - is there a recommended torque or is it a nip up job.

Finally, a stupid question to many.  When timing it up with the r/h pot at TDC, I turn the crank back 32 degrees - is 'back' anti-clockwise as I look at the timing cover?

Cheers again.

Yes anti clockwise. Easy way to remember is yr engine turns in the same direction as your wheels  *smile*

Theoretically the fibre teeth junk should end up being stuck on the sump gauze, but smaller particles may have got through that and then gone through yr pump and back to the oil tank and then recirculated around etc etc, also some junk may still be stuck on the inside of cases.

I suggest you clean the sump and tank gauze filters and change yr oil, run it for few miles and then clean the gauze’s and change it again. Repeat as many times as you feel necessary!

Tip.....use cheap oil.  *work*

Title: Re: Help - bike's gone bang!
Post by: duTch on 16.04. 2018 21:51

 In addition, rather than just rolling the crank back to the required degrees, either go further back and come up to the mark or go right around in working crank motion and come up to it..... this helps remove any backlash in the timing gears
Title: Re: Help - bike's gone bang!
Post by: wortluck on 16.04. 2018 21:55
Brilliant, great info.  Sorry for all the questions but:

Presumably I have to make sure the slipring copper strip is showing on the top pick up which corresponds to the r/h pot at TDC and that the points are on the cam are open.  Is this right.  Just thinking about getting the pot at TDC but having the mag at the wrong point of rotation.  Someone mentioned fag papers in the points - how do you time the points with the position of the piston?
Title: Re: Help - bike's gone bang!
Post by: KiwiGF on 16.04. 2018 22:03
Brilliant, great info.  Sorry for all the questions but:

Presumably I have to make sure the slipring copper strip is showing on the top pick up which corresponds to the r/h pot at TDC and that the points are on the cam are open.  Is this right.  Just thinking about getting the pot at TDC but having the mag at the wrong point of rotation.  Someone mentioned fag papers in the points - how do you time the points with the position of the piston?

Too much time wasted messing about with points  *problem* is why I installed an electronic mag! You could do the slip ring thing or just swap the leads over if it won’t start.

You have to (repeatedly  *problem* ) turn the engine forwards and feel when the fag paper is let go. Then se how far before TDC it is.

Practice makes perfect etc, everyone has a preferred method *problem*

You are lucky if the mag pinion does not move slightly when you tighten it making the process a bit of trial and error (but then having an electronic mag I’ve had less practice than most  *smile* )
Title: Re: Help - bike's gone bang!
Post by: Greybeard on 17.04. 2018 10:45
In addition, rather than just rolling the crank back to the required degrees, either go further back and come up to the mark or go right around in working crank motion and come up to it..... this helps remove any backlash in the timing gears

Yes indeed.
Title: Re: Help - bike's gone bang!
Post by: wortluck on 17.04. 2018 15:59
Thanks all

I take it that the timing method is trial and error.  I get the fag paper thing now, but is it (the fag paper) released at 32 degrees BTDC or at TDC.  I'm guessing points start to open at 32 degrees (fag paper pulls out) and are fully open by TDC (points at apex of camring).
Title: Re: Help - bike's gone bang!
Post by: a101960 on 17.04. 2018 19:39
If you want to eliminate an doubt about when the points are about to open, forget fag papers and get one of these. Best thing I ever did. The one I have lights up an LED, and buzzes when the points are just breaking. It makes life very much easier when timing a magneto. I have no idea how it works, but take it from me it does.
(https://www.a7a10.net/forum/proxy.php?request=http%3A%2F%2F&hash=d56b4b7995135993e6b438e299f2e6c5)
https://www.ebay.co.uk/i/282869499077?chn=ps&adgroupid=54682298551&rlsatarget=pla-413984951703&abcId=1133906&adtype=pla&merchantid=6995734&poi=&googleloc=9045594&device=c&campaignid=1058607774&crdt=0
Title: Re: Help - bike's gone bang!
Post by: chaterlea25 on 17.04. 2018 19:51
Hi Wortluck,
When setting the timing, do not forget to wedge the auto advance unit fully against the spring action
Points just breaking at 32 BTDC,(fag paper comes loose)
I would not be without my mag timing gadget, old age is a bastard *ex*

John
Title: Re: Help - bike's gone bang!
Post by: Greybeard on 17.04. 2018 19:56
If you want to eliminate an doubt about when the points are about to open, forget fag papers and get one of these. Best thing I ever did. The one I have lights up an LED, and buzzes when the points are just breaking. It makes life very much easier when timing a magneto. I have no idea how it works, but take it from me it does.
(https://www.a7a10.net/forum/proxy.php?request=http%3A%2F%2F&hash=d56b4b7995135993e6b438e299f2e6c5)
https://www.ebay.co.uk/i/282869499077?chn=ps&adgroupid=54682298551&rlsatarget=pla-413984951703&abcId=1133906&adtype=pla&merchantid=6995734&poi=&googleloc=9045594&device=c&campaignid=1058607774&crdt=0

I have used my multimeter to show the change in resistance when the points open but it's not easy keeping croco clips on the bits as you fiddle so last time I used fag paper and it worked fine.
Title: Re: Help - bike's gone bang!
Post by: wortluck on 17.04. 2018 20:20
This is really helpful fellas but: How and where do you attach the timing disc?
Title: Re: Help - bike's gone bang!
Post by: duTch on 17.04. 2018 21:56
 I've never had fag papers, but a bit of tinfoil works as well, can easily tear so be careful to retrieve it all.
Title: Re: Help - bike's gone bang!
Post by: muskrat on 18.04. 2018 07:21
G'day wortluck.
To use a timing disc (degree wheel) you need to drop the primary cover and cush nut and put it behind the spring. Easier if you have an SRM cush nut as it has holes to attach a wheel. At least it's not a job you have to do often, most owners never.
Cheers
Title: Re: Help - bike's gone bang!
Post by: wortluck on 18.04. 2018 16:18
Cheers duTch and muskrat.  What about those things you screw into the spark plug hole.  From what I can work out, the stroke of a Flash is 84mm which you divide by 180 (degrees).  This give a figure of 0.47mm (to two decimal places).  This means that for every 0.47mm the piston is moved, it is equal to 1 degree (BTDC in this instance).  As I need 32 degrees BTDC, 32 x 0.47 = 15.04mm, so I just move it back until this figure is reached and that should be 32 degrees BTDC.  If this is so, then no need for a timing disc attachment.

By the way, I've got my fibre drive and 20l of cheap oil (£34 inc delivery).  It seems a good spec oil for the price but my plan is to drain the existing oil, clean the gauze, filter and oil tank.  Refill the oil to about half a tank and run for a few miles.  Drain that off and repeat the process once more before filling with usual 20/50 - does this sound about right to get the missing teeth out of the engine.

One last thing, anyone know where I can get rivets for the ATD repair, otherwise I'll get them made by my engineer fella.
Title: Re: Help - bike's gone bang!
Post by: duTch on 18.04. 2018 16:29
 
Quote
From what I can work out, the stroke of a Flash is 84mm which you divide by 180 (degrees).  This give a figure of 0.47mm (to two decimal places).  This means that for every 0.47mm the piston is moved, it is equal to 1 degree (BTDC in this instance).  As I need 32 degrees BTDC, 32 x 0.47 = 15.04mm, so I just move it back until this figure is reached and that should be 32 degrees BTDC.  If this is so, then no need for a timing disc attachment.

 I don't think it quite works like that...the piston travel is greater between 45º either side  of half way up/down, due to angular trigonometric geometry stuff, and Pythagarus theorum... *eek*..
 There's a chart here somehere that calculates it all. Off the 'top of my head', the more realistic measurement is something like 5/16-11/32" before TDC -stick down de 'ole method  (TBC)


Title: Re: Help - bike's gone bang!
Post by: duTch on 18.04. 2018 16:40
 Here's a link to a thread with the chart;

https://www.a7a10.net/forum/index.php?topic=195.msg795#msg795 (https://www.a7a10.net/forum/index.php?topic=195.msg795#msg795)


 (https://www.a7a10.net/forum/proxy.php?request=http%3A%2F%2F&hash=d56b4b7995135993e6b438e299f2e6c5)  Tried to 'insert image', but copy and paste may not/ doesn't work *conf2*
Title: Re: Help - bike's gone bang!
Post by: wortluck on 18.04. 2018 16:54
Got it, thanks duTch.  The instructions seem to indicate 5/16 which is 8mm in new money.  So to clarify, I find TDC and measure piston movement with rod down 'ole of 8mm and I have 32 degrees BTDC - please tell me this is right.
Title: Re: Help - bike's gone bang!
Post by: dave55 on 18.04. 2018 17:29
Have you tried Dixon Hall in Wakey for the rivets ? not much they don't sell ?
Title: Re: Help - bike's gone bang!
Post by: wortluck on 18.04. 2018 17:49
Cheers all.  It's just the size of the rivets I'm not sure about.  Also not sure if they'd be 'off the shelf'.
Title: Re: Help - bike's gone bang!
Post by: duTch on 18.04. 2018 18:03
 
Quote
......  So to clarify, I find TDC and measure piston movement with rod down 'ole of 8mm and I have 32 degrees BTDC - please tell me this is right.....

 Yeah- fairly much...to find TDC, is easier to roll it one way down a bit and note the measurement, then back  the other way the same distance down and split the difference- if that makes sense ?

 I may be missing something in that due to when I do it is usually with the Primary off and looking at the crank.... an aside note - dunno if it's just the cranks I have, but have noticed that the split-pin hole in the end of all my cranks seems to align with ether the big-end pin or 90º (can't remember which but all the same)

  Don't forget to come up to the mark as I mentioned earlier ^^^
 


 **edit- my method may also be a bit vague due to 3am here drinking beer trying to figure out why my Macbook files are all saved/stored/created/logged 12/12/2018 (or whatever year)...and may have a call about 5 to go to work *pull hair out* ...if anyone has clues I'd be grateful
Title: Re: Help - bike's gone bang!
Post by: RichardL on 18.04. 2018 19:09
Guys,

Remember this? Enter stroke and rod length and Robert is pursuing canubial relations with your mother's sister.

http://www.a7a10.net/BSA/ignition%20timing%20converter.xls

Richard L.
Title: Re: Help - bike's gone bang!
Post by: muskrat on 18.04. 2018 20:41
Ignition timing for the Long stroke is 0.313" for 1947-49 and 0.375" for 1950 btdc. I can't find figures for the con rod length to use the calculator.
Cheers
Title: Re: Help - bike's gone bang!
Post by: wortluck on 18.04. 2018 21:37
Cheers Musky, what's your take on the timing for a 1961 Flash.  I make it 0.3125 or about 8mm.  Seems to be a lot of variation as to how people set it up - quite confusing.  I reckon I'll have to get my mate to take me through it then I should be ok.  Any info out there to suggest the dimensions of the rivets holding the fibre drive to the ATD?

Look, I really appreciate all the info.  The skills for maintaining these machines lie with a relatively small number of 'older' people, so I think of myself as an apprentice really.  I don't have the confidence to do some jobs for fear of it costing me a fortune to put right if I screw it up.  On the other hand, if I don't do them, I won't learn and it may become harder to find people who do.

With this in mind, I'd like to thank you for your patience - long may it continue.
Title: Re: Help - bike's gone bang!
Post by: trevinoz on 19.04. 2018 00:34
Talk to Andrew and buy the kit.
It comes with everything that you need.
Title: Re: Help - bike's gone bang!
Post by: bikerboy on 22.04. 2018 01:48
I know those rivets were available from a place called Grove Classics. Ok its a velo dealer but thats where I got mine a couple of years ago
Title: Re: Help - bike's gone bang!
Post by: wortluck on 22.04. 2018 08:37
Cheers bikerboy - I'll look into that. Currently, the ATD is with my mate who's making the rivets (plus a spare set) for me.  May never need them but it makes sense to me.  I've looked at Priory Magnetos and it seems Andrew is not taking new business until July (from the website - please correct me if I'm wrong).  The kit Andy offers is well priced, will probably cost me more than that to get them made but, hey, the guy's going to repair the ATD and show me how to time the beast up (fix and tutorial all in one).
UPDATE:  Have removed oil tank and cleaned out 3 times with brake cleaner, cleaned the feed and return pipes.  Removed sump plate and gauze and OH MY GOD, the crap that was in there. :o  Must have been pretty much all of the shredded teeth, some general crap, and the remains of a small antelope.  *eek* Cleaned all that off with brake cleaner and replaced.  All timing side is as clean as I can get it (tips for removing old gaskets and liquid gasket please).  I used brake cleaner (great stuff) and a very sharp razor blade (at right angles to the case!!) - seemed to work ok.
After the timing's sorted, plan to put a couple of litres of my cheapish oil in, give it a quick run, and repeat once more before filling it up as normal and going for a hell of a run.  What d'you reckon?
Title: Re: Help - bike's gone bang!
Post by: muskrat on 22.04. 2018 11:01
G'day wortluck.
Go for it.
Listen and feel for anything unusual.
5/16" (0.3125", 7.9mm) btdc full advance will work fine.
Cheers
Title: Re: Help - bike's gone bang!
Post by: wortluck on 22.04. 2018 13:14
Cheers musky, and thanks for the timing info - pretty much confirms what my mate said too.  He's a good guy, is 70 and has been running, racing, repairing and rebuilding British iron since he was 17 - knows his stuff.

Will go steady until I'm sure.  I reckon after the second oil change, if there's nothing in the gauze, I should be good to go for it.

Title: Re: Help - bike's gone bang!
Post by: wortluck on 05.05. 2018 19:08
G'day guys.  First up Musky, manual says 11/32 for the timing not 5/16  *conf2*  My mate has now fixed the ATD and the bike's up and running on 11/32 timing.  It's running well except........ it sounds different under load.  Don't want to say detonation, more like a tappety sort of noise - and not all the time??  I've just started using Castrol lead additive and octane booster as I suffered a bit from detonation before.  Super unleaded improved it further and it was running really nicely prior to stripping the mag gear.  Don't know if it's anything really - ideas??
For stripped gear, changed oil twice and cleaned gauze SIX times before taking it for a long run (still bits of fibre teeth in there).  I put the timing cover on using semi-hardening gasket, so checked the gauze again to clean out any excess that may have got in - only a tiny bit there and cover is virtually oil tight.  On that score, my machine pisses oil out everywhere, but not in huge amounts (chaincase, gearbox, forks + seals).  The old tale I heard when I was a kid that British manufacturers made the engines out of old colanders seems to be correct. *eek*
Title: Re: Help - bike's gone bang!
Post by: muskrat on 05.05. 2018 19:47
G'day wortluck.
With todays unleaded fuel (not what we used to know as petrol) ignition needs to be a tad retarded. Any noise, rattle under load is either pinging/detonation or mechanical (big/little end). As you said octane boost and super fuel helped, retarding the ignition will help further. Orabanda did some dyno testing and found best performance was 30.5 degrees btdc.
Cheers
Title: Re: Help - bike's gone bang!
Post by: wortluck on 05.05. 2018 21:32
Cheers Musky, may well be worth doing what you said at retiming 30.5 degrees.  I'm pretty sure it's not big/little end as it doesn't make that noise all the time - even when it's under load.  It's way better than it used to be, and that's a combination of super unleaded and going easy on the throttle (sometimes give it too much of a handful!).  I'll keep you posted and thanks again.

Oh, and it looks like a thread has stripped in one of the timing cover screws.  I'm guessing this might be some sort of helicoil job.  Again, any advice.  At present, it tightens slightly so I've put some threadlocker on it for now.
Title: Re: Help - bike's gone bang!
Post by: a10gf on 05.05. 2018 22:09
Congrats with the engine coming back to life. Agree with Muskrat, try some slight retarding.

Before doing the real timing adjusting, you may try a 'cheat' for testing purpose by decreasing the points gap (if practical). Will retard timing, and one can test if the engine likes it. But mag performs best with correct gap, so go back to normal afterwards.
Title: Re: Help - bike's gone bang!
Post by: wortluck on 05.05. 2018 22:31
Cheers guys, much appreciated!
Title: Re: Help - bike's gone bang!
Post by: morris on 06.05. 2018 11:49
Oh, and it looks like a thread has stripped in one of the timing cover screws.  I'm guessing this might be some sort of helicoil job.  Again, any advice.  At present, it tightens slightly so I've put some threadlocker on it for now.
Easy job. Just make sure to drill and tap as square to the case as possible. The screws are fairly long and the timing case holes tight so any misalignment and the bolt won’t go in.
Title: Re: Help - bike's gone bang!
Post by: bsa-bill on 06.05. 2018 12:08
Quote
Again, any advice.

Helicoil inserts come in different lengths, mostly kits come with X1, this being the diameter of the insert but X2 and X3 can be had so measure how deep you want ( remember you wont be able to tap the full depth).