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jebjeb
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Hey guys, I am really stumped. Bike was running great until I decided to open it up and it bogged out and wouldn't do anything but idle. Messed with carb and it seemed to get better. However, now it does this thing where all the lights (neutral, charging) come on fine when nail is engaged but about a second after you start it, all the lights start to fade and the bike cuts out after a second or two. Thanks for any help.

jebjeb
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Also, when you kick it and it

Also, when you kick it and it doesn't start but the lights are on, every now and then the lights will fade really dim and then come back bright after a few seconds or a couple more kicks.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6736
Check the battery

Check the battery connections. Also, what the state of your battery? These bikes require a good battery in order to run, not like the magneto systems which don't need a battery to power the ignition.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

jebjeb
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Brand new battery from Blue

Brand new battery from Blue Moon. One of the modern 6v copies of the original battery. I have 6.5 volts at the battery and the terminals have been checked a few times. Any other ideas? Thanks.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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What about the coil? Are

What about the coil? Are your connections to the coil clean?

If not that, I'm wondering if you don't have an issue with the circuit board in the headlight. I'm having a hard time connecting the fact that your "opened it up" and now you're having electrical issues.

Besides, can you really open up an R25/2? Laughing I haven't had the chance on mine...I'm only about 150 miles after the rebuild, so still breaking it in. It never really went that fast!

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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Something else...you might

Something else...you might want to look into a new condenser. I've been reading other posts about strange electrical problems...in some cases it's been the condenser.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

jebjeb
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I will check the coil

I will check the coil connections.

Haha yeah, it isn't much to open up thats for sure.

I have been through the circuit board up top and redid the wiring. I have check the connections inside the bucket when the nail is down and it never breaks, just the lights go dim sometimes.

I will try changing condensors.

I noticed that if when the lights dim, I manually open the points, then the lights will come back bright. I changed the points to new points and now I can't get any spark, so I have to sort that out first.

Thanks for the help, keep the ideas coming if it isn't too much trouble.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6736
Hmmm...I wonder if the

Hmmm...I wonder if the problem is that the points are set wrong. In other words, they don't open at all during the rotation, thus no spark. If the points remain closed and never open, then power is flowing through the points to the coil. A coil doesn't like to be saturated like that for a long time. That's the whole purpose of the points...closed, saturated the primary winding then open, the primary field collapses creating a surge of power in the secondary windings, finally give a spark at the plug. If your points never open, you may be overheating the coil.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

scottiesharpe
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Joined: 04/18/2011
Posts: 107
battery

jebjeb wrote:

Hey guys, I am really stumped. Bike was running great until I decided to open it up and it bogged out and wouldn't do anything but idle. Messed with carb and it seemed to get better. However, now it does this thing where all the lights (neutral, charging) come on fine when nail is engaged but about a second after you start it, all the lights start to fade and the bike cuts out after a second or two. Thanks for any help.

Battery hooked up backwards??

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Full Service repairs, maintenance and restoration workshop for vintage and classic BMW Motorcycles http://blog.scottiesharpe.com

jebjeb
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Well, I fought and fought.

Well, I fought and fought. Cleaned connections, checked wires, etc. etc. Turns out the new battery had a broken plate. I must have checked battery voltage 10 times and it always read 6.3 volts. Then, one time it read 4.2 volts and so I plugged in a battery charger which said the battery was fully charged. Took the battery out and found a broken plate. Seriously spent 2 days chasing a broken plate. One time it did start and I kept the RPMs high and the bike ran, so that makes sense.

Getting a new battery. However, that still doesn't explain why the bike died the first time. Thanks for the help, guys.

jebjeb
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I guess it really wasn't a

I guess it really wasn't a broken plate. That is just a common term for it. What actually broke was where the post for the first plate enters into the next cell.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6736
Basically, a bad battery! I

Basically, a bad battery! I think I've heard that in most electrical situations, start at the battery. Of course, checking a battery statically is only part of the story. It should be checked under load...I'm sure the bad cell would have revealed itself in that situation.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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