Got a Tech Question? Know something about BMWs?

Moderator: JimVonBaden


Postby Christmas » Sun Oct 25, 2015 9:44 pm

My 2009 G650GS won't start. 12k miles on it, oil change done in April 2015.

Tried to jump it -- it'll turn on, and engine will start, but once I disconnect the cables, the engine dies immediately. I should check the connections to the new battery I just put in a month or two ago, but from reading the forums, I'm guessing it's the alternator.

My question is, how much is this kind of repair going to cost, and where should I take the bike?
Thanks for the help.

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Re: Alternator?

Postby kioolt » Sun Oct 25, 2015 10:32 pm

Some bikes don't charge at idle. That could explain why yours dies when you remove the jumper cables. I would at least try charging the battery overnight and then putting a voltmeter on it to see how it did. Alternately, before taking the jumper cables off of the bike try increasing the rpm just a little.
2004 R1150RT 177,400 miles , 1991 K100LT 128,700 miles, 1982 R100RT 106,900 miles
Total 413,000 BMW miles
The cheapest thing on a BMW is the nut that connects the handlebars to the seat.
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Re: Alternator?

Postby JimVonBaden » Sun Oct 25, 2015 10:52 pm

Very good chance you have a bad cell in your battery. Sitting will sometimes cause the cells to short out. Replace the battery first. I have a spare if you want to borrow it.

Jim :cool:
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Re: Alternator?

Postby Christmas » Wed Oct 28, 2015 9:46 pm

Turns out that when I put the new battery in, the cables were not completely tight. I took the panels off, and as I leaned on them, I could hear the clock whirring back to life. Explains why my tachometer was going crazy on recent rides too, zooming from 4kRPM to 8K (pegged!) RPM. I guess I was losing power as I hit bumps in the road, then GAINING IT BACK quick enough to freak the thing out.
Anyway, crisis averted. Stand down. :)
Thanks for the advice, friends!
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