F650CS Electrical Gremlins

JustAnotherSquid

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Around 2005ish, we started having electrical problems with the CS. The symptoms:
  • Hard starting.
  • Battery discharging during riding.
  • Burning through batteries every year.
  • Burning through headlight bulbs every few months.
When resuscitating our Beemers in 2020, the dealer found a burnt wiring harness for the headlight. Problem solved!

Or so we thought. The new (in 2020) battery just puked all over our garage floor, so I'm pretty sure we still have issues.

I want to start checking at the most likely problem and then work my way down the list from there. I'm suspecting the first thing I should check is voltage across the battery while the bike is running, which if above 14V would indicate a regulator problem? I'm hoping that's what it is, as upgrading to a mosfet regulator will be relatively cheap and easy.

Does anyone more knowledgeable than me (which would be approximately 7.9 billion people minus one) have any input?
 
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bmart

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Yes. We can talk later if I'm ever out of meetings. Do you have the service manual?
 

bmart

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Any progress? We need to book brake fluid time too.
 

JustAnotherSquid

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Due to a huge backlog of motorcycle work required (especially with RRR only six weeks away!), and limited opportunities to get it all done, the only thing I've done so far is top off the battery with distilled water and keep a close eye on it. So far it hasn't burped/puked again.

I definitely want to attack KK's master cylinder this week or this weekend. Help would be great if you can swing it, but if not there are enough videos on YouTube that I should be able to muddle through it.
 

bmart

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If it is fixed...

Let's book the swap. Weekend weather looks crappy...again. I could likely to do an evening or the weekend.
 

JustAnotherSquid

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I dug into this a bit this morning. Voltage across the battery is 12.1V when the bike is off and 14.0V when the bike is running, so the regulator should be fine.

While I was in there I noticed the dealer never put a vent line on the new battery, and when it burped/puked it spewed acid all over the frame, hoses, and wires. Powder coat is destroyed and frame is already rusted in many spots. Fortunately KK sells a product that adheres to rust and protects the metal so we should be able to prevent more damage. But still, it's frustrating. Especially given how much we paid to resuscitate the bike.

And yeah I put a new vent line on.
 

bmart

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Battery acid and brake fluid suck. All fluids suck. Dealers certainly suck. I'm sorry that it made a mess.

12.1 with the key off is waaaay low. You'll be asking a lot of the charging system. I'd bring it back to the dealer, have them give you a working battery and fix the mess they made.

12-volt-diagram.gif

battery charge.jpg

battery-state-of-charge.jpg
 

JustAnotherSquid

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Thanks. I just rechecked and got 12.47V with the bike off. Not great according to your chart, but not terrible either. The first time I checked I probably didn't have a good connection to the + terminal as it is hard to reach. It took me a few tries to get the 14.0V while it was running, for example.

I think I'm going to splurge on an Antigravity battery when this one dies. Both of the SVs have Lithium batteries and, knock on wood, they are awesome.
 

bmart

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12.47 isn't bad in these temps, but it is lower than all of my old, some ancient, batteries.
 

JustAnotherSquid

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So the latest gremlin is that the brake light doesn't work (tail light does). I bought some new bulbs and they did not fix the problem.

Neither the front nor the rear brake works, so it's definitely an electrical problem somewhere.

I haven't researched this beyond the bulb and won't until tomorrow, but if anyone has any bright ideas I'm all ears. :)
 

JustAnotherSquid

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One of the wires going to the taillight is broken at the connector. Which makes sense because it looks like it was pulled taught from the factory. I'm surprised it lasted this long.

And of course, the wire comes straight out of the main wiring harness, so I can't just unplug a short harness and replace it. Going to have to solder in a connecting wire and heat shrink over the whole shebang I guess? Hell if I know. I'm bad at electrics (and everything else).
 

bmart

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Easy work if you want help. Still easier if we can do it here. You'll probably want to wait until there isn't 20 yds of mulch in the driveway, to ensure you won't have to spread any.

Seriously, need assistance?
 

JustAnotherSquid

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Am I on the right track as far as the ideal solution goes? If so I can probably muddle through it ... leaving us more time to ride. :D
 

bmart

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No need to harness swap. Wire repairs are easy and generally stronger than the wire alone.

Q1: Why did it break? Manufacturing, routing, corrosion, rubbing, etc?
Q2: Can we get to it easily to drop the mic...I mean solder and a few strands of copper if we even need that? If we can't heat shrink (if even needed) we can tape. I use bright blue so I always know where past repairs are.
 

JustAnotherSquid

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A1: My guess would be being pulled taught combined with the vibration from the single. A little slack probably would have worked wonders.
A2: Yes, it's easily accessible. Thanks for that at least, BMW.
 

bmart

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Happy to help. Again, easier if it is here instead of there. Handling work, issues with my dad remotely, mulch, and tryign to squeeze in a little fun. I'm 1/2 step from the straight jacket in a padded room. Most (my dad included these days as he is aging) enjoy beating on others when they're down, but I find that helping someone makes me feel a lot better.
 
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