1963 Bmw R27

[Austy]

I have a 1963 BMW R27. I haven't been able to run this bike for the last 4 years because of what I believe is an electrical problem. The bike will start but will only run for a short time and it seems like when the bike gets hot it shuts down. I have no idea what the problem is or even where to start.
If anyone has any ideas on what the problem might be let me know. I'm not too machanically inclined but if I have an idea I think I may be able to work through this problem.
Thanks.
Austy

[AdminGuy]

I'll take a few wild guesses just for fun. I know nothing - don't forget that.

Floats, float needles, in carbs not functioning properly. Coil expanding from heat and shorting. Coil body must be insulated/floating.

I think you should locate a knowledgeable person or a good shop to look it over.

Anyone else?

[Pete Gagan]

Hi Austy:
If memory serves me correctly, you R-27 probably has a magneto. Should this be the case you may have to have it rewound. Magneto windings become corroded internally, and tend to short across when they get hot, causing shutdown. Sometimes, though, a replacement of the condenser can cure the problem.
If it has a coil and battery ignition system, the same thing can happen, but its less frequent.
A good rule of thumb is to get the ignition fixed properly first, then worry about the fuel system, unless the latter has an obvious problem.
Good Luck,
Pete Gagan

[Austy]

Thanks for your quick response. I had thought that it sounds more like a condenser problem than a carb problem but I guess time will tell. I guess I will start with the condenser and coil. Thanks for you immediate response to my question.

[AdminGuy]

Ah-HA! See- I know nothing.
I think a 12v coil should have a room temp. resistance of around 3 ohms. A 6v around 2ohms. I think....
Resistance of 1 ohm or less would indicate a short in the winding. Heat the coil up a bit and test it again.

Do not test for resistance with any current flowing. Disconnect everything from coil. Coil looks good - insulate with a strip of plastic soda bottle or something when you stick it back in mount. Do not over tighten clamp.

Ohhhh.. I just found this. Ahh it's a single. Are you running all original stuff?
What a nice little bike!

Electrical equipement :
Generator Bosch LJ/CJE 60/6/1800 R 5
Voltage regulator Bosch RS/ZBS 45-60 6/1
Ignition coil Bosch TJ 6/1
______________________
Spark plug Bosch W 240 T 1, Beru 240/14 or Champion L 85;
Electrode gap 0.6 mm. (.0236'')
Electric horn Bosch HF 6
Battery 6 volts / 9 Ah.
Ignition system Battery ignition with automatic timing by centrifugal
advance unit
Contact breaker gap 0.4 mm. (.0157'')
Initial ignition timing 7º BUDC (Governor weights in initial position)
Maximum advance 42º BUDC (Gocernor weights fully spread out)

I also was just reading this from the BMW "Very neat" web site bmwmotorcycles.com

Are they admitting fault???? By gosh -I think they are! ...sort of. It was good to see that they aren't burying the war involvement anymore. Yahhhh - it's a fact. Some more earily factory photos would be cool.
I took this below directly from the site. Ok, so I'm way off topic. But I thought it was interesting.

The Pressed Steel 'Star' Frame . BMW took a temporary departure from the conventional tubular frame with the pressed steel "star" frame. The name "star" may come from the German word "stark" which means strong. This pressed steel frame was incorporated into motorcycle design back in the industry's infancy. One possible reason for the switch was economic necessity. However, a more practical reason may be that at the time, the 24BHP engine of the R36 might have put too much stress on the tubular frames of the time. The Achilles heel of tube was the attachment of the rear drive housing by two bolts. This (*These) bolts compromised the strength of the frames possibly causing them to yield under higher stress. The alternative pressed steel frame encircled the rear drive providing added rigidity to the once weak spot. BMW ultimately returned to the tubular style frames in 1936, never offering a pressed steel frame to the public again.