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Autor Thema: BMW R25/3 the coil question again  (Gelesen 2548 mal)

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BMW R25/3 the coil question again
« am: 04 Juli 2016, 18:50:50 »

Hi Everyone

Yesterday (Sunday) i took the R25/3 1954 for a motorcycle gathering, but unfortunately, bike just died 30Km after the journey started...it was a very hot day here in PT...and engine case and gearbox were hot to the touch...(probably around 40-50C i would say)
Everything seemed right, gas, compression, etc etc but almost no spark (or none).I always thought that i had a weak spark in could, and the coil seems to be from the 50s.(wire leaving coil to spark plug is still tin soldered...old style)
After trying several things, i had to give up the ride and call for the trailer pick-up.
The beautiful journey with my 300 "friends" riding old bikes...ended. Bmw R25/3 being the worst bike in the all group :)
Next time i will catch them.

So...my question.  Since "original" ignition coils are expensive (the ones that fit inside the housing) and they will continue to suffer from heat, i was wondering if i could take the 2 wires (one from points and the other from rectifier/regulator) to the outside, and put a cheaper ignition coil bellow the gas tank.

Is this possible and reliable?
Any 6V coil will do?




I know that the bike will look a bit different from original (coil below tank), but i can maybe start to run the bike safer without coil issues.
50Km non stop would be a good goal :)

Please advise.

Kind regards
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BMW R25/3 the coil question again
« am: 04 Juli 2016, 18:50:50 »

rolf

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Re: BMW R25/3 the coil question again
« Antwort #1 am: 04 Juli 2016, 21:01:29 »

Suffer from heat....yes, of course....after 50 years ;D
Expensive? ...roundabout  50-60€...how much for your coil?....is this really for battery-ignition?
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Re: BMW R25/3 the coil question again
« Antwort #2 am: 04 Juli 2016, 21:07:48 »

Hi Rolf,

Thank you for your help.

Yes for battery ignition. R25/3 still all original OLD parts  ;D

60 euros plus 16€ shipping to PT is expensive for a coil...and it will suffer from heat again and again...
I would prefer buying a 20€ general one like pictures above here in PT and put the coil outside the bike.

Just need to know if its ok and what brands and references do you recommend.

thank you.
G.
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Re: BMW R25/3 the coil question again
« Antwort #3 am: 04 Juli 2016, 21:35:02 »

I don`t believe it.
The first seemes to be for a CDI-Ignition and the second for a magneto-ignition.
Not for batterie-ignition.

Take better a look for Bobinas  ;D like this one.

And by the way: shipping costs from germany to portugal 9 €.

Clemens
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Re: BMW R25/3 the coil question again
« Antwort #4 am: 05 Juli 2016, 00:05:22 »

Hi Cledreda.

thank you for pointing that.

And by the way: shipping costs from germany to portugal 9 €.

Usually German  shops charge 19€ or even 23€ depending on size of package for shipping. Very few only charge the real value, since they also charge for handling and for process initiation etc etc.

coils like lucas cylinders are to big to hide below gas tank.

Why do you think they look CDI coils?

can someone suggest a small ignition coil, suitable for "bellow" the gas tank option :)

i think R27 uses one.

thanks
G.




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Re: BMW R25/3 the coil question again
« Antwort #5 am: 05 Juli 2016, 13:11:57 »

Hi G,
I only believe it looks like an Coil for a cdi-Ignition.

To big Lucas-Coils means 62 mm diameter an the length of 152 mm ist to big?
What`s about this? (40 mm/130 mm)
A good one, the Beru ZS215, (40 mm/105 mm), isn`t cheap.

By the way: Put your old ignition coil out and under the tank. Test the west an hope the best.
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Re: BMW R25/3 the coil question again
« Antwort #6 am: 05 Juli 2016, 15:57:05 »

Thanks again for the links Cledrera.

I also found this topic:
http://bmw-einzylinder.de/forum/index.php?topic=11716.0 for the Beru ZS215

For what i understood in that topic, he installed the BERU coil below the gas tank. It would be nice to see some pictures of the installation. :( to see how it looks.

I could use my old original coil, and put it outside, for fresh air, but i think its to old and spark looks a little weak, even-tough the bike runs perfectly fine..cold :)

I want to be sure to be able to make some Km in a hot day ...lol

Anyone has pictures of a "bellow gas tank coil" for share?

Kind regards
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Re: BMW R25/3 the coil question again
« Antwort #7 am: 05 Juli 2016, 15:59:22 »

For what i understood in that topic, he installed the BERU coil below the gas tank. It would be nice to see some pictures of the installation. :( to see how it looks.

stupid of me...he already have pictures in topic :)
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Re: BMW R25/3 the coil question again
« Antwort #8 am: 07 Juli 2016, 17:45:51 »

By the way,
don`t throw the old coil away.
For example the einzylinderforumsmember ( ;D , my english isn`t goog, but my scotch ...) Hansdampf needs an old damaged one to create a new born one (old iron-inside with new copper-wire outside).
Contact him in case of interest.

Clemens

PS: I shi.. on 12V  8)
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Re: BMW R25/3 the coil question again
« Antwort #10 am: 12 Juli 2016, 13:58:33 »

No...it is not for batteryignition
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Re: BMW R25/3 the coil question again
« Antwort #11 am: 15 Juli 2016, 17:09:34 »

Hi Everyone,

i friend of mine offered me a Jawa CZ ignition coil.
Just like this one:
http://www.jawashop.com/Detail/10314


Its 44mm per +/-95mm

Should i bother to test it or is this coil not ok for BMW R25/x?

Regards
G.
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Re: BMW R25/3 the coil question again
« Antwort #12 am: 17 Juli 2016, 11:58:52 »

Test it.
But: You are the first Tester.  ;D
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Re: BMW R25/3 the coil question again
« Antwort #13 am: 17 Juli 2016, 21:57:40 »

Test it.
But: You are the first Tester.  ;D

Just did some testing, battery connected directly to coil, open and close circuit by hand, but i have no spark with this coil. The only spark i have is from the DC part ;)
I believe its a thryristor coil type.

Here are some pictures of the original coil and the spark it produces after 3km ride (coil was warm)
It seems week and old...but maybe thats just me.





Spark:
https://www.youtube.com/watch?v=nZh7aZVPR98&feature=youtu.be

Well i have to find a new one.
Do you really advise to buy a new original coil and put it in original place, or should i get a different one, and put it under the gas tank.

Thx
G.
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Re: BMW R25/3 the coil question again
« Antwort #14 am: 17 August 2016, 11:21:08 »

Hi Everyone.

I end up buying this one:
http://www.ebay.de/itm/282106831257

Just spray it in black paint, but it was not needed...its just a extra precaution, black paint helps heat dissipation by convection, since no much of air flow under the tank.
I have spark, so i mounted it.







I couldn't test engine running yet, since i also treated the gas tank, and i am still waiting paint to dry.(POR-15)

I hope coil does not fail me soon...that is to much work to replace it, under the tank. Grrrrr

regards
G.
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