Author Topic: Pulsing / jerkyness at low speed constant throttle  (Read 758 times)

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  • Offline mrlm   gb

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    Offline mrlm

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    Pulsing / jerkyness at low speed constant throttle
    on: Jun 17, 2022, 12.23 pm
    Jun 17, 2022, 12.23 pm
    Are other people experiencing pulsing / jerkiness when riding at a constant low speed?

    If so what speed gear RPM does it occur at for you?

    I am aware that due to Euro emissions standards bikes run lean in closed loop which along with narrow band O2 sensors can cause this but it was happening at 30mph in third gear last night which is higher speed and rpm that I have experienced it before on other bikes. The last tank of fuel was normal Shell E10 95. I have put V Power E5 99 in now to see if it makes a difference, but I absolutely should not need to use this fuel and I cannot see it being water contamination / ethanol issues in the fuel in summer.

    I have a Dimsport Rapid Bike Easy from my last bike which modulates the O2 signal fed to the ECU altering the AFR. This could sort the issue along with slight fuel consumption increase but I have not seen it used on Euro 5 bikes and may need to get the correct connectors for it. Has anyone had any experience of this on Trident 660 or a related engine (675/765?)

  • Offline Shandy   gb

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    Offline Shandy

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    Re: Pulsing / jerkyness at low speed constant throttle
    Reply #1 on: Jun 17, 2022, 01.56 pm
    Jun 17, 2022, 01.56 pm
    Hi Ya,

    Yeah, unfortunately I experience the same issue and you are correct it's know as a 'flat spot' in the engine. In able to pass ridiculous Euro emissions standards, the ECU starves the engine of fuel at certain revs. On the TS660, it's around 3k revs and like you say, that's precisely 30mph in 3rd.  :138:

    Annoying as it is, I now use 2nd until above 30mph and that seems to be a bit of a workaround.

    I experienced similar issue on my old Kawasaki Versys 650. Although that still uses a cable throttle so the fuelling is a lot worse. In general I find the Triumph fuelling super silky smooth, until travelling at 30mph in 3rd.

    The Kawasaki had a load of aftermarket accessories available and you could get a power commander to sort the fuelling issues. But as the TS660 is so new and the fuelling is otherwise very good, I doubt you'll find one.

    I plan to get a new full exhaust system in the future, mainly so that I can de-cat the bike and let that sweet 660 triple breath as it should without being smothered by Euro Bureaucracy. But to do that the bike will need to be re-tuned. This re-tuning will be the best, most accurate way to get rid of the flat spot, by flashing the ECU and then re-programming it as it should be.

    It's an extreme measure (and not cheap) but unfortunately there's little else to do other than ride at 35mph everywhere or drop a gear into 2nd.

    It seems to be the sweet spot in modern 650cc ish engines, just where the Euro emissions are taken from. If you do get it tuned and see the power curve, you'll notice it happens throughout the rev range at certain points, it's just we rarely maintain a steady throttle higher in the rev's.

    It's certainly not just you, and certainly not limited to the TS660 either. You can thank those  :172: in Brussels for ruining your otherwise superb motorcycle.

     :431:

  • Offline mrlm   gb

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    Re: Pulsing / jerkyness at low speed constant throttle
    Reply #2 on: Jun 18, 2022, 06.44 am
    Jun 18, 2022, 06.44 am
    As long as it's not just me then. I hadn't considered it was just the flat spot because I didn't think they caused the pulsing but you are right it doesn't seem to happen below 3k or above 3.6k rpm.

    It is ridiculous that the speed and gear we use most in this country is the one where the issue is most apparent. Riding around in 2nd is asking to go into the back of someone and causes excessive noise etc. I prefer to ride more relaxed in traffic so I just have to put up with more gear changes from 4th.

    Power commander may not have a specific harness for this bike yet but it is too many wires piggybacking all the sensors anyway and I don't want to have to get someone else to dyno it.

    If it is tuned I need to know it will not cause a tamper error on the ECU which the dealer has to clear. I should be able to look at the map with TuneECU as it just needs a few numbers in a table changing. It cannot possibly be that complicated.

    I think the simplest fix might be the 17t sprocket as it will simply shift the rpm vs speed a little.

  • Offline Mike46   fr

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    Offline Mike46

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    Re: Pulsing / jerkyness at low speed constant throttle
    Reply #3 on: Jun 18, 2022, 01.08 pm
    Jun 18, 2022, 01.08 pm
    constant low speed?

    witch speed ?30km/h more ????? I find my bike perfect on long distance at 70/90km/h

  • Offline domoincan   ca

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    Offline domoincan

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    Re: Pulsing / jerkyness at low speed constant throttle
    Reply #4 on: Jun 18, 2022, 02.24 pm
    Jun 18, 2022, 02.24 pm
    ... You can also ride in a higher gear.  If I'm just putting along at 30+ mph (50+ kph) I'm usually in 5th gear.  The engine doesn't strain at all if you want to speed up a little and if you are riding just a little under 30 mph you still have 4th gear that should be fine.  And to back up the point, if you were riding as per the engine run-in suggestions from the manufacturer, you would probably be in similar gear ratios.  3500 rpm only got me to 74 kph in 6th gear.  Seems like it should be lugging, but it's fine as long as you keep it above 3k.   ... my 2 cents anyway ... definitely not a wheelie ready state of riding.   :745:

    Don

  • Offline markjanemhan   ca

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    Offline markjanemhan

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    Re: Pulsing / jerkyness at low speed constant throttle
    Reply #5 on: Jun 18, 2022, 04.52 pm
    Jun 18, 2022, 04.52 pm
    I'm surprised at complaints of jerkiness at low speed.  It's something I just don't experience with my TS660, in fact it's by far the smoothest engine fueling-wise that I've had in my last 5 bikes (Buell XB12R, Yamaha MT09, Aprilia Shiver, KTM 790 Duke and now TS660.)  I actively tried to make it happen yesterday by riding at a consistent 50 kph (30 mph) in 3rd gear, and no flat spot\jerkiness at all.  I did find with my ultra-jumpy KTM that chain adjustment was critical to reducing the jerkiness - so I wonder if those experiencing this have excessively loose chains?  Just a thought. Maybe some of our bikes have updated firmware?  No idea, other than it's a complete non-issue with my bike, but I understand the frustration it causes - all my previous bikes bugged the crap out of me!

  • Offline mrlm   gb

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    Offline mrlm

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    Re: Pulsing / jerkyness at low speed constant throttle
    Reply #6 on: Jun 18, 2022, 10.28 pm
    Jun 18, 2022, 10.28 pm
    Honestly it's not terrible and now I have looked at it more it's not an issue. I just wondered why it's was at a higher speed than I expected but the flat spot /
    emmisions tuning explains it.

    At the end of the day all ICE bikes do it now at some point and it won't be hard to avoid or fix.

  • Offline BillyHey   scotland

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    Offline BillyHey

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    Re: Pulsing / jerkyness at low speed constant throttle
    Reply #7 on: Jun 19, 2022, 09.34 am
    Jun 19, 2022, 09.34 am
    *Originally Posted by markjanemhan [+]
    I'm surprised at complaints of jerkiness at low speed.  It's something I just don't experience with my TS660

    Same here, and as a new rider it's something I'd be more likely to have experienced.  I was out yesterday, plenty of mixed riding conditions and bike was silky smooth in traffic no matter what gear I was in.  Also tried 30 in 3rd and no issues.

  • Offline Smurf73   gb

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    Offline Smurf73

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    Re: Pulsing / jerkyness at low speed constant throttle
    Reply #8 on: Jun 19, 2022, 04.06 pm
    Jun 19, 2022, 04.06 pm
    I'm still running it in but I find the bike to very smooth especially compared to the early MT09 I rode.

  • Offline Mickleblade   fr

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    Offline Mickleblade

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    Re: Pulsing / jerkyness at low speed constant throttle
    Reply #9 on: Jun 20, 2022, 01.44 pm
    Jun 20, 2022, 01.44 pm
    You could probably fix this fueling issue by playing with TuneECU

     


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