Suddenly no spark.

Begonnen von Studsgaard, 25 April 2017, 14:37:34

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Studsgaard

Hi Guys,

First of all I am sorry to write in English but my German isn't good enough for this issue.
I have a 1953 BMW R25/2 and it is giving my some grief.
Yesterday I was full throttle on an open slightly uphill open road. All of a sudden the engine died and the red charge/no charge light came on.
After a long walk home I pulled the spark plug and it had no spark at all! I had earlier the same day done some work in the headlight (replaced the fuse and the speedo light bulb). I therefore checked all wires and didn't find anything obvious.
Going through the connections I discovered that the condensator loses connection to the ground in the headlight when the ignition key is pushed in and the red charge light comes on. This is perfectly normal. BUT it doesn't lose connection to ground on the battery or engine case! - is this normal???

Regards
Christian
Denmark.

PS. Bonus info: I have lately had a feeling that it is loosing power. Not sure if it has anything to do with the above. Also when I started the bike yesterday before the ride I noticed it left quite an oil cloud on the wall behind me....new piston rings?

Studsgaard



rolf

Hey Christian,
I don't understand: the condenser looses connection to the ground  in the headlight? You have a Condenser in the Headlight?

But first: the hedbulb and the fuse hasn't anything to do with it, the fuse is a fuse for the lightning....not for ignition or loading

Studsgaard

Thanks for your input Rolf.
I don't have a condensator in the headlight. Only the one by the by the magnetos.
I'll try to clarify.
With everything off: Using my multimeter I can confirm a connection between the condensator and the ground (I used the ground in the headlight which has number 31 on the schematics.) If I press the key and engage the ignition the connection is lost which is how it should be. If I check the connection between the condensator and the battery ground or engine case I don't lose connection when the ignition comes on. This doesn't sound right to me and could be the reason for no spark at all?

Regards
Christian

rolf

Try it again (with attention to the contact breaker) Connection of the condenser to ground....when he is open? also when he is closed?
There should only be connection to ground when the contact breaker is closed (he is the one who gives the ground contact)...try it and write again.
Greetings
Rolf

Studsgaard

Thanks for your patience Rolf.
Just to make sure we are on the same page I've attached a screen shot from: http://www.snafu.org/restore/uandm_bmw_v1.pdf.
This shows that the connection between '2 magneto' and '31 Ground' is lost when you press the ignition key. This it also what I measure in the headlight AND between the condensator and '31 Ground'. But not if I test directly between the condensator and the battery negative pole - or the engine case for that sake. Then the connection is permanent no matter the ignition on/off.
I am thinking I might have a short circuit somewhere?

Rütz

Hi,
the 1-cylinders have a battery-ignition, only the /2 twins have a magneto-ignition.
Thus the "#2 magneto" pole in the headlight is unused in the 1-cylinders.
There must not be annything connected to the #2-connector!

As Rolf says, ground connection of the condenser just depends on the contact breaker, absolutely independent from ignition key.
I never dared to be radical when young.
For fear it would make me conservative when old. (Robert Frost)

Studsgaard

You are of course right - both of you. I was looking at the wrong diagram and measured at the wrong terminals. Sorry for my ignorance!

I've done some more research this morning.
Firstly:
With the ignition OFF I measure 6V at terminals 51 and 30 next to the coil/condensator. With ignition ON I also get 6V at terminal 15. So far so good. I can also measure 6V at both sides of the coil and at the condensator. Shouldn't I get much more than 6V at the 'spark plug side' of the coil?
If I lift (open) the contact breaker with the ignition on I get small sparks at the breaker.

Secondly:
I measured the connection between the condensator and the battery negative (ground). Below is a small overview and I hope it makes sense.
With ignition OFF and contact breaker open - 'yes' indicates there was a connection between the condensator and the battery.
                                            IGN OFF.        IGN ON.
Contact breakaer open.              yes                no
Contact breaker closed.              yes                no

When I did this a second time to make sure I got it right I measured connection in all configurations...please help!
Does this have anything to do with the condensator being charged or not?

Is the only function (apart from light/horn) of the ignition key to provide 6V to the coil (terminal 15)?

THANKS!

ToWo

Hi Christian,

you are aware that the "/2 " Notation has _nothing_ todo with the R25/2 ? "/2" talks _only_ about the flat engines. It's a common mistake made in europa. (Besides: the description of the ignition timing is wrong).

There is a manual for the R25/2 available - unfortunatly not in english. But nevertheless you'll find the right wiring scheme within: it should be sufficient to understand the connections.

//Tom


rolf

I know my english is not very good.....but not so bad:
"Try it again (with attention to the contact breaker) Connection of the condenser to ground...".....and, as everybody says...ignore battery at first....measure to ground....ignition off!

Studsgaard

I get your point Rolf and I am listening...thanks for the peptalk.
Just did what you said. Battery is off (literally), ignition off and I am able to detect ground on the condensator with the contact breaker open AND closed...
I made a small video which hopefully can be seen here: https://www.dropbox.com/s/m23flv72sclzh9h/Video.mov?dl=0


rolf

you can't detect ground ;D...when the condenser is in contact with the Ignition Coil....then , when breaker is open, you measure the resistance of the coil (perhaps 3-6 Ohm)....closed 0 Ohm
Disconnect the condenser from the coil....and once again

Studsgaard

I actually just tried this BUT I left the condensator connected to the coil and disconnect the other side of the coil at terminal 15. (This is just a screw instead of having to solder.). Now the ground breaks from the condensator when I lift the breaker...
Is that ok or do I need to disconnect coil and condensator for a bulletproof result???

rolf

That is ok enough ;D...but did you see the difference now? in spite of the connected Condenser?

Screw now together (oh...my pidgin english ;D) all wires....and clean the Breaker contact....with brake cleaner oder Aceton....  watch if there is a spark at the spark plug...if not...reduce the spark plug gap to (roundabout) 0,2mm...now a spark?...when you start with the kickstarter...are there sparks between the contact breaker ?

Studsgaard

Great Rolf, thanks.
I'll do that right away and revert.

In the meantime I followed the wire from terminal 15 and back to the headlight. (At 15 it connects to the coil by the way). In the headlight it connects to 3 other wires of which one is the horn. The other 2 I can't find but one of them is ground!?

Heiko

Zitat von: rolf am 26 April 2017, 15:15:43
Screw now together

Alter.... ich kann nicht mehr... das ist ja geil.... screw now together....  ;D ;D ;D  :lol: sorry Rolf.... aber das war das Beste was ich auf Denglisch gehört habe.


Heiko
Ariel motorcycles... upon which the sun never sets.

cledrera

Heiko,
schäm Dich.
Ich habe Schmerzen.  :lol: :lol: :lol:
Du bist im Recht; nun sieh zu, wie du da wieder heraus kommst. (v. Chamisso)
Lieber Einzylinder als zwei Fallschirme (v. mir)

Studsgaard

Yep that brought a very welcoming smile to my face in the otherwise frustrated atmosphere here in a cold sidewalk in rainy Denmark.
By the way Rolf. FYI I measured 1.6 OHM over the coil when open and 1.0 OHM closed.

rolf

Ich habe ja gesagt "pidgin english" ;D....I am heavy on wire, not true?

back to the other roots ;D
1 Ohm or 1,6 Ohm? never 0 Ohm?....it can depends of poor quality of your ohmmeter..if you put the 2 wires of it together...also 1 Ohm?

Studsgaard

My multimeter reads 0,3 Ohm when I hold its two connectors together.
Just tried again and now the coil reads 0,6 Ohm closed and 1,6 Ohm open. All wires connected, ignition and battery still off.
I initiated a deep cycle of my battery and now waiting for it to fully charge before trying for the spark...
It's a new Blitz battery. I fully charged it before use and rode 60km since. It measured 6,18V when I initiated the cycle this afternoon.

Heiko

Christian,

My feeling is that your battery has a short circuit sometimes and that you have no problems with the ignition. Charge the battery. Fit it in your bike and try to start. Measure the voltage at the same time and see what happens. If it breakes down your battery is damaged. And olease, dont't tell Manfred250 that you have a Blitz Batterie.


Heiko
Ariel motorcycles... upon which the sun never sets.

Studsgaard

Thanks for the input and advice with regards to battery! Didn't even know there is an alternative. The last Blitz was replaced as it didn't hold charge.
Could it be the condensator and any way to check that?

Borgward

Heiko, you are right, there are some symptoms for a faulty battery . But is this the only explaination for the engine breakdown?  ???

rolf

"could it be the condensator and any way to check that?"

Yes....as I wrote....sparkplug gap reducing to 0,2mm and so on.

Studsgaard

Thanks Rolf, I didn't know that was to check the condensator. I will proceed with your instructions as soon as the battery is ready. Probably tomorrow morning.

ToWo

Zitat von: Studsgaard am 26 April 2017, 17:51:56
Could it be the condensator and any way to check that?

Your multimeter is capable of checking Capacitance. You already detached the condensator - so it should be no problem..

//Tom

rolf

Ooooh...I forget:
when the breaker is open....there must be (!!) more than 1,6 Ohm....it must be "unendlich"....most Ohmmeter shows 1 (= unendlich)...the same as you don't connect the wires ot the ohmmeter with something (understand??)
Do you have 3 Pertinaxslices (?) for the screw which connected condenser and breaker....the screw must be(!!) isolated from ground, so that really the breaker makes connection to ground (0Ohm) or not (=unendlich=1)
have a look to answer 13 of this threat:
http://www.bmw-einzylinder.de/forum/index.php?topic=1156.0
I hope this explains my pidgin...if not...ask !

OldsCool!

unendlich = infinite  ;D
Ich bin auf dem Dorf aufgewachsen. Ich wurde nicht erzogen, ich habe ÜBERLEBT!

rolf

Danks!
...bin einfach zu faul für jedes 2. Wort einen translater aus dem Internet zu bemühen...das kann ja denn auch der Fragende machen ;D

Studsgaard

News from the Danish sidewalk.
After a deep cycle of my battery I measured 6,78V this morning.
Before mounting it I made this little video for you Rolf. Testing ground and measuring the resistance of the coil.
https://www.dropbox.com/s/pmbx8g9chzws6cw/Video%20resist..mov?dl=0

Ground seems okay but the resistance seems constant. Probably a stupid question: Am I short circuiting through my fingers? I realized I was resting the hand on ground. Laughing is granted.....

Anyway, I put everything back together and had a spark! The engine started at first attempt and I measured 6,1V at the battery at idle and 6,4V while revving to approx 50%. I went for a 15min. ride (speed 60 - 80 km/hr) and everything was fine. Afterwards I measured 6.44V at the battery. Is the battery not being charged enough?

I am of course happy 'The Black Widow Lizzy' is running again but quite frustrated i don't know why. Would have been nice to find the smoking gun. I am afraid to break down again anytime due to an intermittent spark.

rolf

Short circuiting by your fingers....
how tall are you?....if you are longer than 5mm....forget it, the resistance of your body is too high for short cuts

6,3-6,4 V is the normal voltage of the battery...the higher volts (6,78V) is only after getting it from the charger (for a very little time)...if the battery stands alone....after 20 Minutes it is fallen to 6,3V

Controll the resistance as you have done before....but this time with pressing to all sides the screw....or (better) look if you have really the 3 Pertinax slices
Do you have cleaning the contact breaker? if it was greasy before....that could be the fault

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