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"scratching" noise when off throttle

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by horto15, Nov 12, 2008.

  1. Hi all,

    I have noticed lately that when I take my hand off the throttle (e.g. coasting to a stop at a red light) there is a noise that I can best descibe as a scratching sound. It never happens when I am on the throttle only when I release it and so far as I can tell it is coming from in between my legs (i.e. engine). I thought that it might be engine backfiring (similar to on a car that is running rich) but having never heard it on a bike I'm not sure. It seems to go faster or slower fairly well in sync with the revs on the bike. I have also noticed that fuel efficiency has dropped a fair bit from about 215km a tank to about 190 or less.

    Any ideas? Any help would be greatly appreciated. Is it just in need of a service? I recently had it serviced but the sound pretty much started occuring soon after the service. If i need to take it back I will describe the problem specifically but thougth the first call would be you guys, the netrider community

    Thanks in advance!
  2. Without being there, physically...
    You'll get all sorts of different ideas.

    So here's mine
    How about worn disc pads?
    And you just don't hear it with the throttle on?

    Spin the wheels with the engine off, and see if they still make the same noise.

    Even if it isn't the pads, it will help rule out the wheels / wheel bearings as the culprit.

    None the less - hope someone is able to help you out, soon!
  3. My geuss would be the chain. My bike used to do that somestimes. It goes quiet under load, and as the chain slackens it rubs on all sorts of things.

    Do you have a centre stand???

    You may just need to adjust your chain or replace it all together.

    good luck with it mate.

  4. If the noise changes with the engine revs, then it's probably not the brakes or chain, as those sounds increase/decrease with the speed of the bike. Sounds like an engine problem.

    It may be the camchain rattling, I don't know without hearing it. But if it's coming from the engine, the good news is you should be able to replicate the sound with the bike on the stand. Hopefully that'll get you a bit nearer to the source.
  5. Thanks for the suggestions guys, I will have a look at it on the weekend and see what I can work out. Will post back on Monday. Cheers!