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Have I f*cked it? (Excessive Valve Noise)

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by CBR1KF, Jun 3, 2006.

  1. Hiya Folks,

    I have a CBR1000F. I was riding along on all of a sudden the bike started to make a lot of valve noise and lose power. I took the Valve cover off and I found that the locknut on one of the valves had come loose.

    The bike had ran for a few mins with the exhaust valve clearance in one valve at 5mm!

    After putting the locknet back on and resetting the clearance the noise is still there (although not as noisy), and there is a noticible lack of power.

    So what would be wrong? I know the piston isn't holed as it isn't blowing any smoke.



    Any ideas?
     
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  2. The valve might be bent and not seating properly.
     
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  3. Take it to a mechanic asap.
     
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  4. It will be pretty sick no doubt. Running is only going to make it even worse so stop doing that.

    Id say its going to need the head removed and the valve replaced at the least. :cry:
     
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  5. Yep I have to agree, sounds like your going to have to give it a Head Job
    at the very least ........ like yesterday :?

    *schoolkids chukle* he said head job hehehehehehehehehehe
     
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  6. Hi cbr
    The nut & tappet coming loose would not bend valves.
    Make sure you have the cylinder concerned on the right stroke when resetting valve clearence. Best way is to rotate crankshaft direction of rotation, (same way wheels rotate) watch inlet valve go down and come up again, line up marks on flywheel to TDC and you take your settings from there
     
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  7. If the valve clearance opened up (5mm) then it should not have damaged the valve, it just would not have opened the valve correctly on the inlet or exhaust stroke (depending on which valve) giving decreased power. Best bet would be to reconfirm that the clearance on said valve is now correct, also check all other lock nuts are tight (sorry if i sound like a nobber, just in case), and then perform a compression check, if all good it saves taking the head off unnecessarily.
     
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  8. Hey Coon ;)

    The way you hammer antiquated bikes (like they are the latest model), I am
    not surprised. It looks like your knee will last longer than your bike.
    Try a handful of dirt in the crank. Can't hurt.

    Hurrgh !!!


     
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  9. Smee's call: take it to an expert; I bet it will cost you less than asking for a professional opinion on an amateur internet forum.....
     
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  10. Can't hurt anything by checking the compression, if it's suss he can then try his luck at "The Mechanics" for $80/hour...."yeah mate, all the valves are R/S, full head service required, best to do the bottom end while we are at it, blah blah blah....
     
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  11. Hey Mr Damage; Dapto???? I'm in Balarang......
     
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  12. Yep a Dapto dawwgg...
     
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  13. Yeah i agree, but as a mechanic with 22years experience i can give a good educated guess on the information suplied, plus I did own one of these a few years ago and after doing a full rebuild/rework I know the TDC to valve clearance.
    All we can do on here is offer advice on what is told to us, its up to the poster him/herself to work out what (if anything ) they wish to do with that advice and try to seperate the good and bad.
    :p
     
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  14. for screw and locknut tappets, they'll generally work themselves out - increasing clearance. The valve will still seat correctly and not contact the piston. The lift will just be virtually nothing giving poor performance on that cylinder.

    This is the opposite of shim under bucket valve adjustment, where the on way a valve can increase clearance is to have a shim split and fall out of the bucket or the valve springs give up and stop lifting the valve or the retaining clip comes off the valve stem. Any of these means the valve will not retract fully possibly resulting in the doom and gloom from bob.

    For screw and locknut though, as this is what you say it is, my money is on a very simple fix assuming that the locknut did not come adrift and start floating around. The lack of power might be a bent stem, but may also be something as simple as incorrect adjustment in finding TDC for that cylinder as bob has said.
     
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