Slow Starter Motor - K-Bikes.com - Excellence in Motion
 
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Old Aug 24th, 2009, 1:09 pm Thread Starter
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Slow Starter Motor

I am experiencing an intermitttent slow starter motor on my '08 GT. Turn the bike off when fully warmed up, go to restart and the engine barely turns over to the point that you wonder if it will start. Last time it actually wouldn't start, so I turned the ignition off, then back on and it started no problem. Of course it won't duplicate this at the dealer. Doesn't seem to be a battery problem, as it turns over strong after cooling down.

Any thoughts?

Steve Sylvester
Paso Robles, Ca

'08 K1200GT
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Old Aug 24th, 2009, 1:42 pm
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Simple answer: Odyssey PC680-MJ battery (MJ= Metal jacket for higher operating temp. environments). Did it to mine about 10 months out. Never looked back.

BMW stock battery doesn't cut it.


Mack
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Old Aug 24th, 2009, 1:46 pm
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Mine had a similar behavior, until the battery drained trying to start and I had it towed to the dealership. Turned out the power cables to the starter motor were not secured properly and they had backed off a bit. Some corrosion had started on the surfaces. So the resistance was increasing and the connector could actually shift a little (the tech said he was made aware of the problem when he grabbed the cable and it shifted) meaning some times the connection was even worse.

When in doubt, apply more throttle.
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Old Aug 24th, 2009, 9:11 pm
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Just wait until you stall it at a light with cages behind you honking and you trying to start it, and it turns over soooooooo....slowly. Nice to hear a stronger battery is available as an upgrade, may not wait for the original to die.

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Old Aug 24th, 2009, 11:28 pm
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I didn't. I put an Odyssey in it real quick and tossed the OEM even quicker.

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What was that middle thang?
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Old Aug 25th, 2009, 7:29 am
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I don't get it

I don't get it. If the "strength" of the battery was the culprit, wouldn't the problem manifest itself when you first start the bike up, when it's cold or has been sitting around in the garage for awhile?

After riding for a couple of ours, at a gas stop, shouldn't the battery--even if it's not the "strongest" on the market--be fully charged and hot to trot?

Either I'm missing something, or this "replace the battery" solution makes no sense.

An inquiring mind wants to know.

Don Goldberg
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Old Aug 25th, 2009, 8:42 am
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Interesting. Maybe the problem is that this engine requires more force to turn over when it gets hot, as I have heard is a problem with high performance, high compression engines in race cars, airplanes, etc. I would like to know what cranking amps are available from the stock vs replacement batteries for a start, but I would think that would affect the LENGTH of cranking time rather than the FORCE available from the starter motor that's doing the work. Engineers???

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Old Aug 25th, 2009, 8:58 am
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Cold engine is looser and cranks readily.
A hot engine is tighter and compression goes up = Poor starter!
Think aircraft engines that sound like they are coming apart when cold, or the old Corvairs.

Starter efficiency goes down once hot.

Battery efficiency also goes down when hot. That's also a reason hybrid cars kept the battery packs away from the engine compartment and use external cooling vents as well. Keep any of your household batteries in the fridge to minimalize chemical activity?

Also, the stock battery rests atop the engine in an enclosed spot (A really dumb idea, like putting a catalytic converter under a transmission and wondering why their cheap-ass rubber seals harden and leak on the RT's <damhik! ). No doubt it gets very hot there. If you check the Odyssey literature, the non-metal jacketed one is rated up to around 117 degrees. With the metal jacket on, it goes up by around 50 degrees (insulation and distribution of heat evenly with less warpage of the plate material).

Dump the stocker.


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Old Aug 25th, 2009, 9:08 am
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Hey Mack, is the PC680MJ a plug and play unit? No shims, special connectors, etc. needed?

Dale
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Old Aug 25th, 2009, 11:26 am
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Only mod I did was to make a bracket-shim out of some 1/2" wooden dowel wrapped with electrical tape as the battery is a bit short on touching the mounting bracket. Someone suggested bending the bracket or removing the grommets. Wasn't a big deal, but it does crank and start like it should now. I was embarrassed enough in front of some H-D'ers enough when it did the slow-crank at the fuel pump and I pushed it out back to figure it out.

Fwiw, no need for a "Hot-Start" button as on a Yamaha - something done to the ignition timing and fuel to let people kick 'em over easier when hot. Ask some dirt bike Yami owner about them as they are unknown to most of the non-BMW crowd. I believe they used, and maybe still do, the button on both kickers and battery jobs since the late '90s when engine cc and compression grew so as to settle out tight clearances and unload any hot fuel expansion which made them almost impossible to start once heated up.


Mack
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