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Old 11-24-2008, 02:15 PM   #1
GOROVN OP
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F 650 GS Gearing

The gears on the f650 gs are a pretty tall. Currently it has 17 and 41 tooth sprockets. I would like to try a 16 and a 15 to see which works better. I cant seem to find anyone who carries them.

Has anyone changed the gearing? What is a good source for these parts?

BTW, the BMW dealer says they cant even get the 16 which is stock on the 800.
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Old 11-25-2008, 04:49 AM   #2
JRWooden
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I have heard the same front sprocket(s) are use on Aprilia bikes so you could try starting there....

Dropping to 16T front sprocket as first attempt would be pretty easy and inexpensive....

Jim
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Old 11-25-2008, 05:48 AM   #3
RobTheRigger
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Would dropping the front one tooth and raising the rear one tooth be too much? Just wondering, so I wouldn't have to mess with chain length.

-Rob
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Old 11-25-2008, 05:55 AM   #4
GOROVN OP
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16 / 42 is stock on the 800, i wouldn't think that would be too much at all.

(the stats were given to me by the local dealer - hopefully they didnt make a liar out of me)
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Old 11-25-2008, 09:56 AM   #5
Dave92029
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Detuned 800CC = different gearing?

I was talking with a friend that has a 800CC and it appears that my F650GS gets much better fuel economy than my friends 800GS. I also love the gearing while riding the twisty's in the mtns.

I'm curious if you change the gearing to the same ratio as the 800CC how that effects the "detuned" 800cc engine power curve in the 650GS. The 800GS power curve is different than the 650GS so doesn't that have to be considered when adjusting the gearing?

Hope I'm making sense but the two bikes have different tuning so shouldn't the gearing also be different?

I've wondered why it has taken this long for this topic to be discussed. Doesn't the gearing benefit where you do most of your riding: dirt vs highway and everything in between?

Which ratio would be best for each surface? Would this be different for the 650GS vs the 800GS?
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Old 11-25-2008, 11:47 AM   #6
John Ashman
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The theory is that the 650GS makes more power lower and is more of a street bike so the taller gearing is better. But for me, I wonder why they didn't just space the gears out slightly more and then run the same ratios for both. I don't see the point of closely spaced gearing with a nice powerful engine. For a 250cc engine? Sure.
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Old 11-25-2008, 05:07 PM   #7
Ed@Ford
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Quote:
Originally Posted by John Ashman
The theory is that the 650GS makes more power lower and is more of a street bike so the taller gearing is better. But for me, I wonder why they didn't just space the gears out slightly more and then run the same ratios for both. I don't see the point of closely spaced gearing with a nice powerful engine. For a 250cc engine? Sure.
Countershaft sprockets cost BMW pennies, new gearsets are VERY expensive. Rumor has it the 800GS and the 800S interchange the trans gears. BIG BIG cost savings.

Since the 650 has a 1000RPM lower peak torque, it can easily deal with 1 more tooth on the front C/S compared to the 800. In my opinion, having road tested the 800 and the 650, both have highfirst gear and reasonably low RPM @ 60mph. The 650 has way more top end than necessary in the USA, I plan to go with the 1 tooth less 800 C/S sprocket. Also if you calculate out the #/horsepower, the 650 is BETTER than the 800, so the 650 with the 800 C/Ssprocket should be better than the 800 in roll on and 0-60 but give up top end.

I went down one tooth on the C/S of my 2003 F650 Dakar, and the fuel economy loss was unmeasurable, and low speed off road stuff was MASSIVELY improved. There was plenty of adjustment to take up the chain slack. I assume the same will happen on my F650GS due in January.
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Old 11-26-2008, 12:24 PM   #8
Navaho
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Quote:
Originally Posted by GOROVN
The gears on the f650 gs are a pretty tall. Currently it has 17 and 41 tooth sprockets. I would like to try a 16 and a 15 to see which works better. I cant seem to find anyone who carries them.

Has anyone changed the gearing? What is a good source for these parts?

BTW, the BMW dealer says they cant even get the 16 which is stock on the 800.
I have a 16t sitting on my desk, waiting for my 650 twin to get repaired from a slow speed get off a month ago . I got the F800GS sprocket from a BMW dealer. They had to get it from Germany since there were none in the States.
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Old 11-26-2008, 02:09 PM   #9
Crilly
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Let see, more torque down low on the 650, less weight on the front end, and use the same gearing. IT JUST MITE WHEELY TO EASY. HEAVEN FORBID!
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Old 11-26-2008, 04:44 PM   #10
Ed@Ford
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Quote:
Originally Posted by Navaho
I have a 16t sitting on my desk, waiting for my 650 twin to get repaired from a slow speed get off a month ago . I got the F800GS sprocket from a BMW dealer. They had to get it from Germany since there were none in the States.
How long did you have to wait to get it here?
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Old 11-26-2008, 06:50 PM   #11
Navaho
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Quote:
Originally Posted by Ed@Ford
How long did you have to wait to get it here?
Two to three weeks. Ask your dealer to have it "overnighted" - a term he will understand. Dealers can put a "quick ship" status on any BMW part that signifies that the part is needed urgently, and it will get here a l lot sooner. Shipping may be a little more.
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Old 11-27-2008, 12:48 PM   #12
mrleadfoot67
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Lower Gearing For the 800?

Does BMW have any other sprocket choices other than stock ratios for the 650/800? I'd really like lower gearing for my 800 to help it off road in the slow stuff, give the clutch a break. Does the rear sprocket cross with any other motorcycle? Which Aprilia does the front sprocket cross with?
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Old 11-27-2008, 05:32 PM   #13
MBronskill
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16 tooth countershaft sprocket

I also have a 16 tooth sprocket waiting for installation. Ordered through my BMW dealer in Toronto. It took several weeks for delivery, but hard to tell exactly how long because they forgot to phone me when it arrived. Will report on its effects in due course. Installation is scheduled as a winter project.

Mike
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Old 11-28-2008, 08:49 AM   #14
huckleberry
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touratech has cs sprockets check their site
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Old 11-28-2008, 09:40 AM   #15
GSjoyride
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are you an inmate??

If you are a Chain Gang member F650.com, the Prof. mails you like in 2-3 days a set of new sprockets and a chain for $155.............

Just got mine,

Inmates can get a 520 x-ring chain
rear 49 (NOT stock 47) tooth and 16 tooth countershaft sprocket for $155 mailed 3- Day Priority Insured to USA addresses.
Payment to SR Johnson
PO Box 160074
San Antonio, TX 78280

If using PayPal, add 5%......my account i prof@f650.com
First, let me know who you are.....Peace, Steve
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