I have a Honda CBF125 Stunner. Sometimes when I increases the throttle the bike cannot attain the real speed that matches the RPM and the engine sound changes.

The bike takes more time to attain about 90kmph than earlier.

What may be the problem?

  • Please add other metrics such as odometer reading , year of purchase, service done etc.
    – SaharshJ
    Commented Feb 7, 2020 at 7:46

1 Answer 1


Your clutch might be bad

If your clutch is slipping then the RPM's of the bike can go up but the bike doesn't accelerate as the clutch slips.

Many times a clutch will start slipping when the engine is at a higher power output. If you are operating under higher RPM's in higher gears, this is when the greatest load is on the clutch, chances are you are experiencing this.

You can try and adjust your clutch cable and make sure there is enough play in it. There is a writeup in this answer about clutches regarding howto adjust one. Give that a try first, although you may have already caused damage to your it's best to ensure yours is adjusted properly, regardless.

  • well.. you beat me to it :-)
    – Shobin P
    Commented Jun 12, 2016 at 10:31
  • but the mechanics saying it's not because of clutch. They said there may damage on vacuum ,i forgot its name - inside the carburator.
    – arjun
    Commented Jun 12, 2016 at 10:53
  • 1
    @arjun - If the RPM's of the engine go higher, but the speed does not, something is giving. The only thing which could give is the clutch. The engine RPM to bike speed is always linear: more rpms; faster vehicle speed. Each gear's rpm to speed relationship will be different, but there will always be a constant ratio in every one of them without exception. Commented Jun 12, 2016 at 11:52
  • Sometimes i can fix this problem by the following method. holding the throttle for sometime in neutral. Now the sound changes to normal .and this time the bike behaves normally. aftr sometime it again goes back.
    – arjun
    Commented Jun 12, 2016 at 12:12
  • 1
    Your welcome. Can you make my answer as correct by hitting the check mark next to my answer? Take care, have a great day! Commented Jun 16, 2016 at 3:51

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