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996 996 Stutter When Warm - Sounds Like A Relay..?

Discussion in '748 / 916 / 996 / 998' started by drumm23, May 30, 2020.

  1. Gents!

    My 996 is running really well apart from a peculiar stutter that only starts when warm... rolling on throttle from about 2k to 4k it sounds like a relay is clicking somewhere under the dash and very briefly killing the ignition - every now and then it seems to jerk the throttle in my hand. I have read about the switch to a single injector solving a 3.5k stutter ... is this what I have or is there some relay that could be causing my issue?

    (It runs on to 9k no problem and if you keep the revs up above 4.5k then it doesn't happen.)

    Many thanks for any help :upyeah:

    Drumm.
     
  2. Gents .... I made a video to help show the issue ... you can hear the click ... but the sensation of it impacting the throttle in my hand doesn't come across ...

    It only happens when the bike is hot, after maybe a few miles of town stop/start traffic. Makes it very jerky trying to pull on to a roundabout or similar as the throttle jerks each time there's a "click" ... My temp gauge only works intermittently and I think the fan is not working correctly either - could these be causing it, could I be overheating? Can't see why that would only cause the click at the 3k to 4k rev range though...

     
  3. Drum, have you tried running it with the fairings off to try to identify where it is coming from, also does it do the same when the clutch lever is pulled in. Could be a number of things but the vid sounds more mechanical to me, almost like a sprag failing, a broken gear selector spring or an issue with a belt tensioner or there is something loose in there.
     
    • Thanks Thanks x 1
  4. Bit difficult to hear properly on a phone but I agree with @Denzil the Ducati, it really sounds mechanical rather than a chattering relay which I doubt you could hear above the engine. As said above the fairings need to come off to try and pin point the sound and take it from there.
     
    • Thanks Thanks x 1
  5. The sprag is tired Denzil - I know that and the guy who serviced it recently said I'd have to do it in a year or two. Didn't think the sprag could cause that but there you go!!
     
  6. Never thought of popping the fairings off - will do that tomorrow and assess :upyeah::upyeah::upyeah:
     
  7. Drum, if you have a big screwdriver you can push the pointed end to area of the crankcase (or wherever) where the noise seems to be coming from and put your ear to the end of the handle to use it like a stethoscope - like this water main listening stick.jpg only much smaller. You can get quite accurate information about where and what an engine rattle is. It is worth temporarily tie wrapping the clutch lever to the grips to get rid of the clutch clatter before you start
     
    • Like Like x 1
  8. A backfire in the throttle body perhaps?
     
    • Agree Agree x 4
  9. It does sound like spitting back, would also account to the slight loss of power or stutter.
     
    • Agree Agree x 1
  10. Update.... got it up to temp, popped the fairings off .... and it was way too loud to identify where the sputter was coming from :D. I only saw the tip on the screwdriver now, I will find one and give that a go.

    I had another suggestion that it might be too lean and to twist the screw beside the EPROM back a bit to the rich side. I did that and felt it improved it but was still there... I was hesitant to twist it too far as the bike is running so well (and starts so well) apart from this little issue. I took it back from about 3 o'clock to about 10 o'clock. I might give it another nudge and take her for a spin when I get a break tomorrow and see how it is.... I'll find that screwdriver too :):upyeah:
     
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