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I am fairly new to motorcycling and have been enjoying my 2009 GSA for just over a year. Unfortunately, I’ve had some mechanical issues with my bike but that’s another story. My question is about the ideal cruising RPM’s for the GSA. I have been told that the battery does not charge very well under 4000 RPM’s and the revs should be kept at this level or higher. I tend to ride in higher gears for improved gas economy, usually between 3000-4000 RPM’s. After a long trip I notice that starting can sometimes be sluggish. Any advice is appreciated.
 

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No worries

IMHO there is no such thing as ideal cruising. This is a (well, more or less) modern motorcycle it can keep your battery charged at idle or any RPM you like. On a highway the ideal cruising is what the traffic dictates on you. On a leisurely afternoon on a back road just let it drop even under 3000, Of course you must know that you can not demand too much from it in this range, but you can love it, and that what counts.

"I have been told that the battery does not charge very well under 4000 RPM’s and the revs should be kept at this level or higher."

Rubbish.The reason for the sluggish start has to be somewhere else, and if it is just a couple more turn of the starter, forget it.
If it really drives you nuts, buy a pocket voltmeter and check your battery, when you feel it sluggish.
Enjoy!
 

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Jeno2 is correct.

Modern alternators are wonderful things. The alternator on your '09 will put out about 1/2 of its 720 watts at idle. That's close to 90 amps. It ramps up to full output by 4000 RPM.

Unless you've got 300 watts of external lighting or other power hogs added to your bike there is enough to charge a battery at any RPM.

Some bikes take a turn or two of the engine to start. Are you holding the clutch when starting the bike (even when in neutral)? It helps the smallish battery installed on our beasts if it doesn't have to turn the transmission, too.
 

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Regarding your concern for the battery charging at low rpm. The alternator will charge your battery at any rpm, but with various cappasity. Use a voltmeter and check the charging voltage at idling rpm. Correct charging voltage shall be 14,5 V.
 

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Cruising speed

After 60k miles on a 1200GS, I find it most responsive (happiest) at 4,000 RPM.
This is most suitable for freeways. It gets best fuel economy between 3,000 and 3,500 which for me is 2 lane blacktops on weekend rides.
 

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I have an '09 R12GS with tall BMW (Ztechnic) screen almost always in the lowest position. I have the winglets installed. I have the BMW GSA aluminum side bags but rarely ride with them. A small RKA tankbag and large TT tailbag covering the pillion seat and GS rack.

I'm 5'8" and maybe 170 pounds. 28" inseam (hence the low Sargent seat -- which is pretty comfortable by the way). When holding steady at 4,000 RPM on the highway (without the aluminum side bags) I get 44 to 46 mpg per the computer. I have 11,000 miles on the bike at this time and boy has that motor smoothed out.
 
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