Flat spot or is it me? - BMW F800 Riders Forum & Registry



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  1. #1
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    Done about 13000 miles and when I got the bike I noticed a slight hesitancy at 4100 revs about 70mph ish particularly when cold but would seem to disappear once warmed up thoroughly.
    I think its much more pronounced now and its like the bike won't make any more power as you gently apply the throttle but then it sort of clears its throat (so to speak) and is away.
    Its also noticeable when warm and not just when cold so not sure if its getting worse ( but if a flat spot that shouldn't happen ) or if its just me focusing on it too much.
    Do other bikes have this or is it just mine in which case I probably need to get into a dealer. I wondered if it could the the throttle position sensor or something but its very acute at 4100 maybe 4200 revs and more noticeable in 5th and 6th gears.
    Any ideas?

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  3. #2
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    My observation is that flat spots are caused by modern fuel injection systems trying to conform to emission requirement regulations. I would be surprised if a dealer could fix this issue unless there is a mechanical problem. You might need some sort of device that will richen the fuel mixture slightly like a Booster Plug, or something similar.
    Richard - Current bikes: 2016 BMW R1200RS, 2018 16.6 kWh Zero S, 2011 Royal Enfield Bullet 500 Classic, 2009 BMW F650GS, 2020 KTM 390 Duke, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior. 

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    4100 is a little low for the "flat" spot. At somewhere around 5000-5500 rpms, mine takes off like an entirely different bike. You can see the hp start climbing sharply around there.

    Chris
    Elnathan - 2014 BMW F800GT
    IBA# 49894 True Rounder = 0-20's - Rounder -- to -- 100's+ Red Hot Rounder

    John 14:6 

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  6. #4
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    This is strange. I would agree you should normally find a flat spot at 5000+ revs but its definitely at about 4100. Once your at 4300 its gone and completely cleared. Being in the UK its really noticeable as 4100 is about 70mph , our max speed limit so your in or around this hesitancy quite a lot.
    I'm starting to think it might be more than a flat spot as its a hesitancy / mini surging with the fueling but only at that rev point. I would expect a true flat spot to feel a bit underpowered but not to hesitate or to pulse surge when holding a steady throttle at 4100 revs.
    I think I will check the throttle cable and the plugs etc before booking it in. Its always been there but I'm now convinced it is getting more pronounced and isn't just in my head !
    Had people said " argh they all do that" then I would have lived with it but I feel a bit more investigation required.
    Thanks for the replies so far.
    Cheers

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    Wife has a 2013 F700, I have a 2014. Mine initially used notably less fuel on trips but was easier to stall and vibed worse than hers. I added the AX-FIED gadget and this has changed the power delivery very nicely. I now have shifted the vibe zone upwards, from 4k to 5k rpm, use a little more fuel. We are now hit reserve within 1-2 km of each other and I almost never stall the bike, along with much better throttle response off idle....actually everywhere, pulls very well from just above 2k rpm
    Summary is I can only surmise that her bike was being fueled more or less correctly from the outset and I had to add the gadget to correct the lean condition my own 2014 was experiencing. My bike is quite delightful now and I can think of no other reason than the gadget is working.
    Greg

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    Longy, cant say I've noticed what you describe on my 2015 700GS,,. Mines very flat on the torque after 7000 which I believe is normal?


    Anjelli,,,,,,,,Haven't heard of this "added the AX-FIED gadget ",,.
    Sounds interesting, what are the details?

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    Quote Originally Posted by Lag View Post
    Longy, cant say I've noticed what you describe on my 2015 700GS,,. Mines very flat on the torque after 7000 which I believe is normal?


    Anjelli,,,,,,,,Haven't heard of this "added the AX-FIED gadget ",,.
    Sounds interesting, what are the details?
    The gadget is a fuel spoofer that attaches to the O2 sensor wire and fools the computer into thinking it needs to add fuel throughout the range. As I mentioned in the earlier post my F700 was quite ornery when it came to plodding along a slower speeds and I have stalled it more often than I have any other bike I've ridden(>50 years). I also noticed that I was using between 5 and 10% less fuel than the wife's 2013 bike but I do ride at least one gear higher(lower rpm) than she does, using lower rpm thrust to accelerate. We tend to ride at a quicker pace, FWIW.
    So, moderately annoyed by the snatchy throttle, seemingly lean condition, too-frequent stalling, the significant increase in vibes above 4k rpm, etc... I did some reading and decided to install the gadget. It fits a very wide range of BMW bikes and I knew I could easily sell it if not happy. Other methods exist to add fuel but I understand that they are soon overruled / corrected by the computer..... however the AF-XIED gadget continues to fuel at the setting you have selected. There are about 11 settings, easy to adjust with a small screwdriver. Easy to install also....I'm slow and spent about an hour doing the install and most of that was peering everywhere to see what I had missed!
    We ride about 20% off road and I like my engines to pull pretty hard from low rpm, on the F700 that means about 2,500. The bike is really quite unhappy much above 6,000 rpm anyway so I don't bother with that area of the range.
    The changes were subtle at first(setting 7) .....a bit better but I wasn't completely sold....but as the miles increased I noticed the improvements more and more. Last summer I went to setting 8 and noticed the fuel consumption increasing slightly, to the point where we narrowed the consumption to 1-2 km difference between the bikes, which is remarkable. I'm typically using 4.1 - 4.2 L/100km, which is outstanding mileage from an 800cc motor, especially ridden as I do. If I spend time at 140++ this drops sharply, of course. I've noticed I'm also running a gear higher(lower RPM)
    You mentioned the power flat after 7k rpm, that is typical for this engine, with the power curve that emphasizes lower-mid-range torque, which I prefer.
    Oddly the wife's 2013 model just runs much nicer than mine did and I don't think she would benefit from the AF-XIED gadget. I have no idea how the 2017 runs, you may not need this gadget....can you say where the vibes become more annoying?
    Little more info on the gadget:
    https://advrider.com/f/threads/poll-...#post-39926978
    Last edited by anjelli; 2 Weeks Ago at 07:18 PM.

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    I have a 2013 F700gs, which used to have a snatchy throttle. I added an AX-XIED device years ago and it seemed to help. I wonder if your wife’s bike has a defective 02 sensor. Perhaps it is causing a richer mixture, which ironically makes the bike run better. It could also have a different ecu map than yours. Perhaps bmw has made the map leaner over the years to comply with emissions regulations.

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    Quote Originally Posted by Kb-f700gs View Post
    I have a 2013 F700gs, which used to have a snatchy throttle. I added an AX-XIED device years ago and it seemed to help. I wonder if your wife’s bike has a defective 02 sensor. Perhaps it is causing a richer mixture, which ironically makes the bike run better. It could also have a different ecu map than yours. Perhaps bmw has made the map leaner over the years to comply with emissions regulations.
    That's my best theory, different/better ecu mapping on her particular 2013 bike, which runs really nicely. She used to get a kick out of teasing me whenever I stalled my 2014 F7, usually at a stop sign. Couldn't let that continue!!

  14. #10
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    "Can you say where the vibes become more annoying?"

    Would have to check,,. Perhaps closer to 6000 and higher,,. having heard your remarks, I'm thinking that what I'm feeling as a wheel balance issue is the vibration zone which comes on at 140 kph in 6 th gear,,. I would say peak vibration is 150/160 kph what ever RPM that is,,.

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    Quote Originally Posted by Lag View Post
    "Can you say where the vibes become more annoying?"

    Would have to check,,. Perhaps closer to 6000 and higher,,. having heard your remarks, I'm thinking that what I'm feeling as a wheel balance issue is the vibration zone which comes on at 140 kph in 6 th gear,,. I would say peak vibration is 150/160 kph what ever RPM that is,,.
    Pull in the clutch and just coast while the engine idles. If it’s a wheel balance issue you will still feel it.

  16. #12
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    Quote Originally Posted by Lag View Post
    "Can you say where the vibes become more annoying?"

    Would have to check,,. Perhaps closer to 6000 and higher,,. having heard your remarks, I'm thinking that what I'm feeling as a wheel balance issue is the vibration zone which comes on at 140 kph in 6 th gear,,. I would say peak vibration is 150/160 kph what ever RPM that is,,.
    I have quite a bit of vibration anywhere close to top speed and I was wondering if my new(not balanced) tires were the culprit. But, reducing throttle significantly or pulling in the clutch pretty much cleaned up the vibes. I find the motor vibration increases with throttle position as well as rpm when running fast. I believe 140kph indicated is about 5k rpm with stock gearing.
    Greg

  17. #13
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    Try downshifting and see if the vibration continues. That changes the engine speed, but not the vehicle speed.

    At 30,000 miles my engine smoothed out noticeably. I don't know what changed, but it did. Prior to that at about 3700 to 4000 rpms was annoying. It was easy enough to stay out of the rpm range, but I definitely knew when I hit it. It wasn't hand numbing, but it was noticeable.

    After 30,000 miles, that's one of the smoothest areas of the rpm range. In fact, the entire engine is very smooth.

    I guess you could say that's encouragement to keep riding. It only gets better.

    Chris
    Elnathan - 2014 BMW F800GT
    IBA# 49894 True Rounder = 0-20's - Rounder -- to -- 100's+ Red Hot Rounder

    John 14:6 

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