Intermittent ignition problems

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Rob Frankhamr
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Re: Intermittent ignition problems

Postby Rob Frankhamr » Wed Aug 14, 2019 10:06 am

That's a good reference... but... it doesn't and can't address the fact that this fault is intermittent. You can only effectively troubleshoot an electric problem when the circuit isn't working properly and, in this case, this will almost inevitably be at a time and in a place where formal troubleshooting is at best inconvenient.

For my part, as an initial and to a certain extent pre-emptive measure, I would check every connection in the ignition circuit and make sure they are all tight and clean. I would then work my way through all of the wires pushing, pulling and wiggling them to see if I could replicate the problem. This would need to be done with the engine running so it would be necessary to rig up a 'remote' fuel supply (in the past, I have achieved this by removing the seat and resting the tank on the subframe with extrs fuel hose to the carbs). If that doesn't produce any results, I would always carry a multimeter and/or test light in the hope that, should the problem occur again, I could carry out some diagnostic tests before the problem, whatever it is, goes away again.

FWIW, I had exactly this situation with my old R45. I would be riding along when the engine would cut out then, after a certain amount of time (sometimes even before I'd come to an involuntary halt) it would go back to normal. The only difference I can see with Petes issue is that the bike was completely dead when it cut out... no electrics at all. If I 'solved' it once, I 'solved' it a dozen times, loose battery terminal, dirty igniton switch connectors etc. etc. but, every time, it would come back again.

The 'lightbulb' moment was when, one day, the problem occured yet again and I ground to a halt... then I happened to move the handlebars and everything came on. Turned out that the problem was the main feed wire from the battery to the ignition switch. This had broken in the loom and was making intermittent contact by touch. When movement of the handlebars or vibration made the wire ends lose contact the bike died. another slight movement made the wire ends touch and all was back to normal. The fix was easy enough... just run a parallel battery feed wire but diagnosis was a grade a class 1 PITA.

Not saying this is the problem here (although it might be), just trying to put over the difficulty of diagnosing an intermittent fault and the importance of observing all of the symptoms, (expecially where they affect other circuits).

No, I'm sorry Pete, I don't have a simple answer...

Rob
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ptjenkins65
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Re: Intermittent ignition problems

Postby ptjenkins65 » Sat Aug 17, 2019 8:37 am

Thanks Rob, that is a very sensible answer. It’s the occasional nature of the problem that’s is most niggling.
The other problem being that the bike is at our place in Italy and I am back in the UK so I can’t just pop to the shed and have a look. When it was in the UK it was just fine. When I get to it I’m will have a good wiggle of all the cables and junctions to see if I can get it to do it again, if it will start at all.
And the white spark, is that an issue too?
Pete
1998 r850r
1979 r45
1974 r60/6
Still learning

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Rob Frankhamr
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Re: Intermittent ignition problems

Postby Rob Frankhamr » Sun Aug 18, 2019 10:41 am

Judging the colour of the spark is at best subjective. I would say that a yellowish spark would be a weak spark, a white spark tending to blue would be moderately strong, certainly strong enough to light the fires in the cylinder. This is born out by what you say in your original post... when the bike stopped there was no spark... as soon as the spark came back, the bike ran. Once started, an engine can run with quite a weak spark so I'm of the opinion that the 'white' spark' you refer to probably isn't a root cause of the problem.

Rob
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Re: Intermittent ignition problems

Postby ptjenkins65 » Sun Oct 27, 2019 6:27 pm

Hi all. I m finally able to get to my bike and see what’s going on.
So on arrival I tried the bike again, no spark. I tested the voltage on the battery, it was low even when charged and dropped down to 12.1 when the lights went on, so I have fitted a new battery, no change. I had also bought a new right hand switch set from Germany, fitted that, also bought a new upgraded live and earth cable set. I have fitted the negative but not the positive yet as it looks to be an involved job. Still no spark. I finally fitted a new set of coils, an updated set. There was a spark. I put the tank back on and pushed the bike outside, no spark again. I have rubbed the yellow black and white black cables together from the Micro digital Boyer box and there was a spark again. I cannot seem to get any kind of reading from the digital timing plate, see photo.
I have checked for continuity and it seems pretty good on the negative side, a little sketchy on the positive.
Any suggestions?
1998 r850r
1979 r45
1974 r60/6
Still learning

Mjolinor
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Re: Intermittent ignition problems

Postby Mjolinor » Sun Oct 27, 2019 6:32 pm

The resistance of one Boyer inductive pickup coil is 69 ohms. Inside the timing cover are probably two coils in series so with the meter on resistance it should read about 140 Ohms.

That is between the two wires going to the engine, away from the Boyer electronic box.

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Re: Intermittent ignition problems

Postby ptjenkins65 » Sun Oct 27, 2019 6:45 pm

Hi . Here is a picture of what I got when I took a reading from the cables running from the plate, black to black and yellow, red to black and white. I had put a fresh battery in the meter
EC6F180C-15B4-4729-8E45-2291BE5396AE.jpeg
Regards Pete
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1998 r850r
1979 r45
1974 r60/6
Still learning

Mjolinor
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Re: Intermittent ignition problems

Postby Mjolinor » Sun Oct 27, 2019 6:54 pm

Hard to see but it looks like open circuit to me. You have either a broken wire or a broken coil.

Time to take it off and check each of the bits.

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Re: Intermittent ignition problems

Postby Doug504 » Sun Oct 27, 2019 6:55 pm

I had an annoying intermittent fault just as you described. Bike ( 1989 R80Rt) would be running fine then just cut out suddenly only to re-start after one or two attempts. Took me a while to sort. Tried cleaning as many connections as possible but the fault would occasionally still reappear. However, since replacing the old fuse box ( 2 ceramic continental fuses) with a more modern “blade” type fuse box the fault has not reoccurred. I took the opportunity to replace with a 4 fuse option giving me a couple of spares for accessories etc. Not saying this is your problem but it may be worth either giving the fuses and holders a good clean or replace with the blade type fuse box.

Doug

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Mark Esposito
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Re: Intermittent ignition problems

Postby Mark Esposito » Sun Oct 27, 2019 7:04 pm

I had an annoying intermittent fault just as you described. Bike ( 1989 R80Rt) would be running fine then just cut out suddenly only to re-start after one or two attempts. Took me a while to sort. Tried cleaning as many connections as possible but the fault would occasionally still reappear. However, since replacing the old fuse box ( 2 ceramic continental fuses) with a more modern “blade” type fuse box the fault has not reoccurred. I took the opportunity to replace with a 4 fuse option giving me a couple of spares for accessories etc. Not saying this is your problem but it may be worth either giving the fuses and holders a good clean or replace with the blade type fuse box.

Doug
Hi Doug,

I raised changing the fuse box in this thread but haven't got around to it yet,

https://www.bmbikes.org.uk/viewtopic.php?t=26659

Airhead mono fuse box

Is there any chance you could (in my thread so not to hijack this one) tell me how you got on , if there were any problems and what fuse box you used

Thanks and sorry for the intrusion !

Mark

Sent from my motorola one vision using Tapatalk


I have a 1988 R80 RT monolever in case i forget to mention it when asking a question ! and I'm based in South Wales

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Galactic Greyhound
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Re: Intermittent ignition problems

Postby Galactic Greyhound » Sun Oct 27, 2019 7:56 pm

Pete,

Intermittent problems are very tricky to find and need to be approached in a slow, methodical manner.
Here are a few tips in order of priority:

1. Each time the intermittent fault occurs, carefully and without disturbing ANYTHING, note down on paper what is working and what is not (e.g. dash lights, instruments, horn, headlight, indicators etc) along with the date/time/mileage, weather/traffic conditions and any relevant symptoms (e.g. suddenly cut out, jerked to a halt, backfired, cranks over but does not fire up, doesn't crank over etc)
(this will allow you to re-assess the problem days or months later if it keeps coming back and help enable a logical diagnosis to be made).

2. Once the fault has been recorded, try and determine what system has failed e.g. Fuel, Ignition, Lighting etc.
(I now carry an HT pen Tester (Ebay £5) for rapidly checking the HT Lead voltage without disconnecting the HT leads).
Also, try moving the handlebars side to side to see if the dash lights etc go On/Off due to a broken wire from the Ignition Switch making and breaking as the bars are turned.

3. If the bike has failed at the roadside, do NOT flatten the Battery by repeated start attempts. If it does not fire up in three short attempts then LEAVE it alone for at least an hour while you make recovery arrangements before making a final short start attempt.
(Quite often electrical failures are heat or damp related and allowing a component/wiring to cool down or dry out can result in it becoming operational again - perhaps at least for a long enough period to get you home.)

4. When looking for an electrical fault, the first thing to ascertain is whether or not there is power (+12v) being supplied to the suspect system.
When testing for power supply, it is better to use a simple 12v bulb such as a 21W indicator bulb than use a Voltmeter.
This is because the 21W bulb will draw nearly 2 Amps whereas the Voltmeter barely draws any current.
The advantage of drawing a larger current is that if there is a corroded electrical connection, the larger current will cause a voltage drop across the corroded connection which will show up as a reduced voltage to, and therefore reduced brightness, of the bulb.
The voltmeter used under the same circumstances, will always show the SUPPLY voltage (i.e. Battery +12v) because there will be virtually no current being drawn by the Voltmeter and therefore there will be NO voltage drop across the corroded connection leading one to think that the circuit is OK when it is not.
You can use your Voltmeter to measure the voltage ACROSS the test bulb and an accurate reading will be given of the voltage at that point because the test bulb is putting a 'load' across the circuit which will cause voltage drop in any corroded connections and this will be revealed by the Voltmeter showing a lower voltage than the +12v Supply voltage.

5. When checking for power to a system or component, it is always a good idea to manipulate any connector or wiring to that system/component while observing the bulb in order to determine if a poor/broken connection exists.


BOYER BRANSDEN

Here is the Boyer Bransden Webpage: http://boyerbransden.com/index.html

If you suspect that there may be a fault with your Boyer Bransden (BB) Ignition System, then the first thing to do is to check what BB system is fitted to your bike.
You should be able to determine this by looking at the type label fitted on your BB Ignition Module.
This info should be noted down in your maintenance manual for future ref as it is a modification to the standard ignition system.

Once you know what BB System is fitted to your bike, then you can obtain the Wiring Diagram for that system from the 'Fitting Instruction Sheet' tab on the BB website.
This will allow you to check that all the wiring is present and connected correctly.
(Is this your BB System - Type Mk3 - KIT00098 ? http://boyerbransden.com/pdf/KIT00098.pdf)

Once the BB System Wiring has been checked, you can now proceed to the 'Fault Finding' tab on the BB website.
This will allow you to test the Ignition System and determine what part, if any, has failed.

If your bike has a 12v Ignition system using two 6v Ignition Coils connected in series, then check that the single wire connecting one HT Coil Primary winding to the other HT Coil Primary winding is sound.
There should be +12v coming in from the Ignition/Kill Switch to the First coil on a Green wire and connecting to Primary terminal '15' or '+' on that coil.
The other terminal on the First coil will be marked '1' or '-' and this should be connected to the Second coil terminal marked '15' or '+' using a single Black wire.
The Second coil terminal '1' or '-' will be connected to the BB Ignition Module.

Note that the HT coils are fired by the BB Ignition Module supplying an earth rapidly On and Off to the Second coil terminal '1' or '-' .
If this BB Ignition Module wire is disconnected from the Second coil terminal, the coils can be fired by rapidly tapping an earth On/Off repeatedly on the Second coil terminal so SIMULATING the action of the BB Ignition Module (akin to 'Points' operation).
In this way, the Coil HT system including the HT leads, Plug cap and Spark Plugs can be tested.
CAUTION: A high voltage can be created on the coil terminal when doing this so take precautions against electric shock by using insulated pliers and wearing rubber gloves and boots.
DO NOT DO THIS TEST IF YOU HAVE A HEART CONDITION OR PACEMAKER!

Let us know how it goes! :smile:
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" - It works!

ptjenkins65
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Re: Intermittent ignition problems

Postby ptjenkins65 » Mon Oct 28, 2019 3:50 pm

Hi Ced, once again thanks for your advice.
This morning I tried the bike again but no dice. I took the timing inspection cover of, checked the wires and on it came. I put the cover back and once again nothing. Took the cover off and after pulling all the fittings apart and putting them back again it started. While running I tried moving all the cables, but nothing happened.
I have a Micro Digital box fitted http://boyerbransden.com/pdf/KIT00086.pdf.
I tried touching the white black and yellow black wires together and got a good spark.
I did notice that when I hit the start button the side light in the headlight came on when the lights were switched off.
Did you see my meter reading for thevstator plate, or lack of it in the earlier Post?
Regards Pete
1998 r850r
1979 r45
1974 r60/6
Still learning

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Galactic Greyhound
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Re: Intermittent ignition problems

Postby Galactic Greyhound » Mon Oct 28, 2019 5:12 pm

Hi Ced, once again thanks for your advice.
This morning I tried the bike again but no dice. I took the timing inspection cover of, checked the wires and on it came.

That is a classic sign of a wiring problem in the area you poked about in.
You should also be alert to any wiring insulation chafing to earth or loose earth connection.


I put the cover back and once again nothing.

Could the cover be touching something when it is mounted?
Also, when fitting the cover screws and tightening them, this may be straining something enough to make it fail.


Took the cover off and after pulling all the fittings apart and putting them back again it started. While running I tried moving all the cables, but nothing happened.

Assuming the engine kept on running while you poked about the cables, it would appear that the fitting of the cover is causing the problem.

Are the cover screws too long and touching the Trigger Unit or its wiring?

Remove the cover and see if the engine runs.
If so, loosely fit the cover and see if the engine will keep running.
If so, fit and tighten the cover screws and see if the engine fails.
This could be an earthing problem - either an earth point is being disabled by the fitting of the cover or the fitting of the cover is causing it to short out or earth a wire.
Check the wiring insulation carefully under the cover for any 'flattening' of the insulation indicating it is being squashed by the cover and earthing.


I have a Micro Digital box fitted http://boyerbransden.com/pdf/KIT00086.pdf.

I'll get a look at that KIT00086 Wiring Diagram later tonight on my Laptop - my mobile is too small a screen!

I tried touching the white black and yellow black wires together and got a good spark.

I believe that indicates that your Ignition Module is OK and that the fault is likely with the Trigger Unit under the cover - looks like this cover is a possible cause of the problem so it needs to be looked at very closely as to what is going on here.

I did notice that when I hit the start button the side light in the headlight came on when the lights were switched off.

This may be another issue or it may be connected to bad earthing.
It may also be a safety circuit to provide lighting when starting at night as normally on modern bikes the Load Relief Relay will turn off the Headlight when starting so momentarily leaving the bike invisible at night - I seem to remember that the /5 & /6 had a safety circuit like this - keep it in mind but leave it for now.


Did you see my meter reading for thevstator plate, or lack of it in the earlier Post?

Yes but my mobile screen is too small to make it out - I'll look again on my Laptop tonight.

Regards Pete
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" - It works!

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Re: Intermittent ignition problems

Postby John Marshall » Mon Oct 28, 2019 5:27 pm

Does the wiring to the trigger unit come straight up and out of the top between the front cover and the timing case inner cover and if so is it pinched or have you like me got a small semicircular indentation to allow the lead to pass through?

ptjenkins65
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Re: Intermittent ignition problems

Postby ptjenkins65 » Mon Oct 28, 2019 6:44 pm

Hi. I have been so intent on the stator plate that I haven’t looked at the top of the cover. I will in the morning and see if there are any problems there.
Thanks all
1998 r850r
1979 r45
1974 r60/6
Still learning

Roy Gavin
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Re: Intermittent ignition problems

Postby Roy Gavin » Tue Oct 29, 2019 3:07 am

Replacing the bullet fuses with blade types is simple - just pull the two flat connectors off the terminals on the back of existing fuse box and push them onto the blade on a large flat fuse - job done!


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