F700 16T sprocket = Gear indicator failure?

Discussion in 'Parallel Universe' started by MrMac, Apr 3, 2018.

  1. MrMac

    MrMac Long timer Supporter

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    A few months back I purchased a used 2017 F700GS for my wife. She was having problems stalling in first gear, which IMHO, was way too tall! So, did my research an installed a 16T front sprocket.. Much better we thought..!

    Well, not long after, she started having problems with the gear indicator going out. It only happened once she hit 6th gear and would randomly come back on after gearing down. Sometimes it would take awhile (even after stopping and starting), sometimes it would come back right away. Figured it was the potentiometer, which the dealer replaced (bike still under warranty). But that did not fix it.. Happened again not long after we picked the bike up (as soon as she hit 6th!).

    So, took it back and now they are telling me it was the sprocket change that is causing the problem! Apparently, the computer gets 'confused' once the bike is in 6th, and can't really tell what gear it is in. From reading the forums, a lot of people have made this swap and yet I've never seen where anyone has experienced the same problem! The bike is still at the shop, waiting for a new 17T (stock) sprocket.. I suppose I could put the old one in just to check and see if that fixes this, but it is a bit worn so it would have to be replaced soon anyway..

    But my question: Does this make sense? Has anyone else swapped a 17T for 16T (or any other swap on a BMW twin for that matter) experienced this same issue? Or is this something unique to the 2017+ models? And yes, I've searched through the forums and haven't found this mentioned..

    Changing sprocket sizes is such a common thing on motorcycles, and yet I've never heard of any others having such issues.
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  2. zero war

    zero war Zee

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    I have a 16T on my 2015 BMW F700gs and I have zero issues with the gear indicator.


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  3. bmwroadsterca

    bmwroadsterca RadioFlyer

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    Can't see how sprocket size and gear indication can be related. The sensor has no idea what sprocket is fitted.
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  4. sieg

    sieg Wearing out tires......2 at a time, day after day. Supporter

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    ^ Yeap dealer BS, I've run 16 and 17 on our 800, 650twin and 700 GSs.

    Just humor them let them put the 17 on and find that that doesn't fix it, it's warranty so they're wasting they're own time.
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  5. The Maz

    The Maz Clueless and lost

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  6. AndyBoundy

    AndyBoundy Adventurer

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    I run a 16t (from an 800) on my ‘17 700 and my neutral indicator is intermittent now. Interesting that you’re having issues too.
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  7. MrMac

    MrMac Long timer Supporter

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    Well, actually I could see this IF, for some reason, they wanted to compare engine speed (RPM) to ground speed (picked up from the rear wheel sensor I would guess). If the actual values are different from 'expected' values, then something is amiss. Now why they would do this, I don't know. Apparently there was a change to the fueling (?) system beginning in '17 that had something to do with EU compliance. I can't imagine this being the cause though.
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  8. MrMac

    MrMac Long timer Supporter

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  9. bmwroadsterca

    bmwroadsterca RadioFlyer

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    Yes, I considered that but quickly dismissed the possibility. Even BMW doesn't make things that bizarre.

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  10. bmwroadsterca

    bmwroadsterca RadioFlyer

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    There are lots of reports about gear indicator failure that have nothing to do with the final drive.

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  11. MrMac

    MrMac Long timer Supporter

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    Interesting.. However, if you are not have the exact same issues (loosing the indicator when you hit 6th gear), then that is important. I would expect the same fault from the same cause. This still leads me to believe it is in a switch or potentiometer, as would yours.
    #11
  12. bmwroadsterca

    bmwroadsterca RadioFlyer

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    There is an adaptation reset function for the gear potentiometer using a GS911. I'd try that first.

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  13. MrMac

    MrMac Long timer Supporter

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    Thanks! Will look into that. I'll be back at the dealer tomorrow anyway so hopefully we'll get this resolved.

    Thanks to everyone for the replies! And if there is someone out there who has made the same sprocket switch on a 2017 F700 without any problems at all, I"d still like to hear about it just to have a good point of reference!
    #13
  14. BygDaddee

    BygDaddee Where do I get a pie

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    It wont be the sprocket

    Are you sure you didnt damage or dislodge or disconnect the gear indicator sensor ?
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  15. MrMac

    MrMac Long timer Supporter

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    Yep, I'm sure. The potentiometer was just replaced anyway, pretty sure they would have noticed if something was wrong .
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  16. Arbolmano

    Arbolmano Not so Studly

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    I put a 16 tooth on my 15 F700 with zero issues. Sure awakened the bike.
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  17. AntReed

    AntReed Been here awhile

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    When I have installed aftermarket gear indicators on bikes I have had to select each gear and run it through the Rev range whilst on a centre stand or paddock stand which I assume was to calibrate the wheel speed to the engine revs?

    If that is the case with the way the onboard indicator works then it could be the sprocket change would cause issues.

    It might be that in 6 at a certain speed the bike is expecting the revs to be x when they are actually y and that throws the error.

    Having said all that, lots of others are having no issues but the dealer have changed the only other thing that could cause the issue so it is a bit confusing.


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  18. Tigershark48

    Tigershark48 My other BMW is a Roadster.

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    No doubt the sensor communicates back to the ecu via wiring. Could be somewhere in the harness. Could also be something in the ecu.

    I could see the ecu throwing an error if rpm doesn’t match mph sensed off the wheel, but I don’t see how it could cause a false gear indication. That makes no sense.

    Not to mention people change sprockets routinely, so the ecu should not be affected.
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  19. SpaffyPD

    SpaffyPD Adventurer

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    I put on a 16T sprocket on my F700gs; at high RPMS [usually in 6th on the freeway] my gear indicator goes blank or or will sometimes display 5th gear when I'm in 6h - as I recall. No issues with ride-ability, shifting, or neutral light. It come back and displays the proper gear when I shift. It had no issues with the 17T nor would I expect it to if I switched back. Not a concern of mine.

    If it has a year basis my 700 is a 2015.
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  20. MrMac

    MrMac Long timer Supporter

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    A little update: Went to the dealer this AM (for some work on my Triumph), and they still stand behind their diagnostics. Can't really blame them.. A couple of things to note:

    1- This is what their diagnostics tool is telling them. Although I'm not sure why they didn't get this the first time, except that maybe there was originally something wrong with the potentiometer as well. And this problem is consistent with similar issues they have seen in other models, just not the F700!
    2- BMW will not authorize any additional diagnostics (under warranty anyway) until the bike is put back in 'stock' condition. So, no matter what I or anybody else thinks, we have to put a 17 tooth back on before going any further.

    Honestly, it wouldn't surprise me that much if this fixes it. Crazy perhaps, but after talking for a bit with the owner of the shop, it is the direction many manufacturers are going in order to tweak performance in every possible way. It is quite possible my F700 has a software version that depends on a stock final drive.. Hopefully I'll know for sure in a day or two. Stay tuned!
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