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Engine stumble at 5000rpm on hard acceleration, but only in 3rd gear

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  • Engine stumble at 5000rpm on hard acceleration, but only in 3rd gear

    Hi All,

    My TLR has developed an annoying issue. For some months I have had the occasional stumble (like the ignition cuts out) under hard acceleration, without being able to make any pattern of it.

    Yesterday it got a lot worse, and there is a definitive pattern to it.

    1. It only happens when accelerating fairly hard (not necessarily wide open throttle).
    2. It happens at 5000rpm on the tachometer, and not anywhere else in the rev range.
    3. It only happens in 3rd gear.
    4. It is very short and the engine will rev past the stumble (i.e. it is not like a limiter).

    Seeing as it only happens in 3rd gear, my suspicion fell on the ECU. I swapped it out for a spare one, but the issue persists.

    Apart from this specific stumble, the engine feels just like it used to.

    Now, I am at a loss to what can cause this issue?

    Has anyone seen this issue before, or have any idea what I should try next?
    TLR '99 (2005 MotoGP Paintjob) - +3mm pistons, flowed heads, PCIII, Dymag wheels, Vandrivers stuff, XtremeGP underseat exhaust and a ton of other goodies.

    TLR #2: The ICE Motorsports TLR - Penske rear shock - Gixxer1000 K7 fork - Matrix M4 Steering Damper - carbon fiber bodywork - carbon airbox - ITG Airfilter - PCII - Full M4 Stainless Race system - Braided hoses - 520 chain conversion - Metzeler Racetec K1/K2 slicks - Metzeler RaceTec Rain K1

  • #2
    Check for loose kickstand switch
    Brainless AT earthling DOT net
    "Take 2 plugs off your Gixxer and it'll sound the same"

    *IMWO = In My Worthless Opinion
    Q2 and Q4's mod list and Albums

    History of Q2

    Q1 Build thread
    Q4 build thread

    Installing Brainless' +Mod Kit -- (Where to buy)
    Starter Relay/Solenoid CONNECTOR Replacement -- (Where to buy)

    Comment


    • #3
      +1


      January 2012 - BBOTM & TLOTM

      Comment


      • #4
        Originally posted by Brainless View Post
        Check for loose kickstand switch
        I can bypass the kickstand switch, and take a test ride. I just don't see why that would only make it happen in 3rd gear?
        TLR '99 (2005 MotoGP Paintjob) - +3mm pistons, flowed heads, PCIII, Dymag wheels, Vandrivers stuff, XtremeGP underseat exhaust and a ton of other goodies.

        TLR #2: The ICE Motorsports TLR - Penske rear shock - Gixxer1000 K7 fork - Matrix M4 Steering Damper - carbon fiber bodywork - carbon airbox - ITG Airfilter - PCII - Full M4 Stainless Race system - Braided hoses - 520 chain conversion - Metzeler Racetec K1/K2 slicks - Metzeler RaceTec Rain K1

        Comment


        • #5
          Originally posted by humle View Post

          I can bypass the kickstand switch, and take a test ride. I just don't see why that would only make it happen in 3rd gear?
          The right amount to vibration at a certain RPM. Don't ask me how I know. Just saying start with easiest possible fixes. And if I recall, bypassing the kickstand switch isn't as straight forward as jumping it. Is it that switch that needs a certain resistance?

          Just make sure it's tight. That's all you need to do.
          Brainless AT earthling DOT net
          "Take 2 plugs off your Gixxer and it'll sound the same"

          *IMWO = In My Worthless Opinion
          Q2 and Q4's mod list and Albums

          History of Q2

          Q1 Build thread
          Q4 build thread

          Installing Brainless' +Mod Kit -- (Where to buy)
          Starter Relay/Solenoid CONNECTOR Replacement -- (Where to buy)

          Comment


          • #6
            Another thought is to clutch it as soon as she stumble. You'll know then if she's dying or if it's just lack of fuel at that RPM. If she dies, she might give you a code.
            Brainless AT earthling DOT net
            "Take 2 plugs off your Gixxer and it'll sound the same"

            *IMWO = In My Worthless Opinion
            Q2 and Q4's mod list and Albums

            History of Q2

            Q1 Build thread
            Q4 build thread

            Installing Brainless' +Mod Kit -- (Where to buy)
            Starter Relay/Solenoid CONNECTOR Replacement -- (Where to buy)

            Comment


            • #7
              Originally posted by Brainless View Post
              And if I recall, bypassing the kickstand switch isn't as straight forward as jumping it. Is it that switch that needs a certain resistance?
              No, just straight short. Mine has been disabled for years.
              ... Listen to Six5 ...

              Comment


              • #8
                Its the GPS
                answered on the zone for you
                www.cycleinnovations.com.au

                It never ceases to amaze why people ask for advice then when I give it they either ignore it or argue against it.
                But then I don't know all that much about TL's

                wwjd.......what would jimmy do.

                Comment


                • #9
                  Pound to a penny someone needs a gearbox.

                  Feels like a misfire; only in one gear; welcome to rebuild central.......

                  Each successive 'stumble' will be polishing the burred over drive dogs / cutouts and it will just get worse and worse til you can't pull third at all; just getting a machine gun type clatter. If you ease off and pull through 3rd at half throttle it will be fine I bet.....

                  My thread title from about ten years ago was virtually the same - but it was 2nd gear not third!!
                  Last edited by popes996; 08-18-2018, 10:50 AM.
                  Buying: Its a cult bike Sir, the prices have stayed high.........

                  Selling: Its a niche bike Sir, the prices have dropped with its popularity..........

                  Comment


                  • #10
                    Originally posted by popes996 View Post
                    Pound to a penny someone needs a gearbox.

                    Feels like a misfire; only in one gear; welcome to rebuild central.......

                    Each successive 'stumble' will be polishing the burred over drive dogs / cutouts and it will just get worse and worse til you can't pull third at all; just getting a machine gun type clatter. If you ease off and pull through 3rd at half throttle it will be fine I bet.....

                    My thread title from about ten years ago was virtually the same - but it was 2nd gear not third!!
                    I have had the thought, but I really hope not.. It also does not at all feel like a mechanical issue, but maybe it fools me.
                    TLR '99 (2005 MotoGP Paintjob) - +3mm pistons, flowed heads, PCIII, Dymag wheels, Vandrivers stuff, XtremeGP underseat exhaust and a ton of other goodies.

                    TLR #2: The ICE Motorsports TLR - Penske rear shock - Gixxer1000 K7 fork - Matrix M4 Steering Damper - carbon fiber bodywork - carbon airbox - ITG Airfilter - PCII - Full M4 Stainless Race system - Braided hoses - 520 chain conversion - Metzeler Racetec K1/K2 slicks - Metzeler RaceTec Rain K1

                    Comment


                    • #11
                      Ride it steady through 3rd; get progressively more load on each run through - if it is load overcoming the drive dogs it will present itself very obviously; happy to be proved wrong but my first one started exactly as you describe - 5k became 5k and 6.5k; then 2, 3, 4, 5 and 7k - it happens as the torque peaks and the dogs jump out of the cut-outs and rotate to the next......

                      If it is the same; start collecting parts..... I rode around it for a few k miles.
                      Last edited by popes996; 08-19-2018, 05:35 AM.
                      Buying: Its a cult bike Sir, the prices have stayed high.........

                      Selling: Its a niche bike Sir, the prices have dropped with its popularity..........

                      Comment


                      • #12
                        Originally posted by popes996 View Post
                        Ride it steady through 3rd; get progressively more load on each run through - if it is load overcoming the drive dogs it will present itself very obviously; happy to be proved wrong but my first one started exactly as you describe - 5k became 5k and 6.5k; then 2, 3, 4, 5 and 7k - it happens as the torque peaks and the dogs jump out of the cut-outs and rotate to the next......

                        If it is the same; start collecting parts..... I rode around it for a few k miles.
                        Well, the testride today unfortunately supports your initial post.

                        Yesterday I checked the GPS (which should not affect the engine, because of my transistor TRE) and the sidestand sensor. I shorted the sidestand sensor to rule that out.

                        But upon riding today, it has gotten worse. It now happens at least twice in the 4-5.5k range.

                        Was it easy to spot the worn parts, and how much of the gearbox did you need to exchange?
                        TLR '99 (2005 MotoGP Paintjob) - +3mm pistons, flowed heads, PCIII, Dymag wheels, Vandrivers stuff, XtremeGP underseat exhaust and a ton of other goodies.

                        TLR #2: The ICE Motorsports TLR - Penske rear shock - Gixxer1000 K7 fork - Matrix M4 Steering Damper - carbon fiber bodywork - carbon airbox - ITG Airfilter - PCII - Full M4 Stainless Race system - Braided hoses - 520 chain conversion - Metzeler Racetec K1/K2 slicks - Metzeler RaceTec Rain K1

                        Comment


                        • #13
                          The amount of wear is so minor it really narks; essentially as soon as the dogs and cut-outs lose their edge it just gets progressively worse.

                          I replaced both shafts, 1st - 3rd gears and forks with all the bearings and as the motor was apart all the engine bearings and gaskets - it was not a cheap undertaking - iirc I spent about 1500.....

                          Lots of alternatives; plenty of engines for sale (over here around 6-700 ?) and either strip and reuse good parts or straight swap if matching numbers aren't your thing??

                          An illustration on 'how little' causes so much grief:

                          https://www.google.co.uk/search?q=mo...&bih=512&dpr=4

                          As the TL has a combined engine/transmission it is a full strip to access the shafts/gears - Like the A Team said; 'if you have a problem and only they can help......' :

                          If you can find him, you could get Sam to build you a monster!!.....
                          Buying: Its a cult bike Sir, the prices have stayed high.........

                          Selling: Its a niche bike Sir, the prices have dropped with its popularity..........

                          Comment


                          • #14
                            Well, it will not be the first time that I take apart a TLR engine, and put it back together.

                            Buying a used engine is an option, but who knows what condition the internals are in. I would rather repair it, to ensure it is in good working order.

                            If it is only the dogs that are worn, why would you replace the shafts?

                            The engine is an overbore already, +3mm (1060ccm) made by Terry Shepherd (before his son took over) and ported heads with a valve job. My other TLR engine (for the trackbike) is a 1080ccm, perhaps I should finish building that engine and put it into the streetbike.
                            TLR '99 (2005 MotoGP Paintjob) - +3mm pistons, flowed heads, PCIII, Dymag wheels, Vandrivers stuff, XtremeGP underseat exhaust and a ton of other goodies.

                            TLR #2: The ICE Motorsports TLR - Penske rear shock - Gixxer1000 K7 fork - Matrix M4 Steering Damper - carbon fiber bodywork - carbon airbox - ITG Airfilter - PCII - Full M4 Stainless Race system - Braided hoses - 520 chain conversion - Metzeler Racetec K1/K2 slicks - Metzeler RaceTec Rain K1

                            Comment


                            • #15
                              Ha - sorry; didn't realise your level of experience!!

                              I had some additional wear which I put down to the mileage the bike had covered; that and I had no plans to repeat the repair if there was any doubt - as it was, the output sprocket bearing collapsed 400 miles after rebuild - I sent it back to the SKF distributor and they said it had missed a heat treatment process!! It was fine the second time round!! The bike was written off shortly after.......
                              Buying: Its a cult bike Sir, the prices have stayed high.........

                              Selling: Its a niche bike Sir, the prices have dropped with its popularity..........

                              Comment

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