On my fuel injected single cylinder air cooled motorbike, it has started bogging at around 4k, feels like it cuts out for a second or until I twist the throttle a bit more. It happens in every gear around same rpm.
I have checked the tps which is good. The throttle cables are fine and lubed and the clutch isn't slipping at all. It has a new air filter and a new plug also.

What other things could casue this problem?
Many Thanks

  • How did you check the TPS?
    – Eric Urban
    Aug 26 '17 at 14:52
  • I backprobed the appropriate wires down at the sensor on the throttle body. Turned bike on slowly turning throttle and read the voltages with a multimeter. The voltage increases and decreases smoothly with no rapid jumps indicating a flat spot. The bike and therfore the tps is only just over a year old with 8900 miles on it.
    – DamoC
    Aug 27 '17 at 16:50
  • If the TPS is functioning correctly, move on to the ignition unit. If the problem is happening at exactly 4k, it sounds like something with the ignition advance may be function inappropriately.
    – Eric Urban
    Aug 27 '17 at 20:05
  • as it is fuel injected and a honda (I can't alter the ignition timing as it's preset by the ecm) could this possibly be a faulty ecm or fuel pump?
    – DamoC
    Aug 27 '17 at 20:20
  • Definitely. Have you checked the spark plug yet?
    – Eric Urban
    Aug 28 '17 at 0:21

I have changed the tps and all problems have now gone.

Lets hope this one lasts as the first one on the bike from new only had around 6500 miles on it before it started playing up.

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