Noisy CB125RS

Discussion in 'UK Motorcycles' started by richard.ingall, Aug 21, 2005.

  1. Hi everyone, a post for all of you handy with spanners! This post is also
    in the Classic Bikes newsgroup, so if anyone thinks it looks familiar, it's
    because I'm getting desperate!!

    Completely rebuilt motor on the RS, yet it still sounds like the big-end has
    gone, despite having a rebuilt crank. Starts and runs ok, makes no
    difference if you pull the clutch in.

    Did notice when I took it for a run that it seemed reluctant to rev
    properly, I put this down to the fact that it hasn't been used in ages, so
    maybe a blocked jet etc....question is, does anyone think the two are

    Any ideas?

    richard.ingall, Aug 21, 2005
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  2. Blocked jet and a fucked crank? No.
    The Older Gentleman, Aug 21, 2005
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  3. In, richard.ingall amazed us all with this pearl of
    Yer bearing shells.
    Whinging Courier, Aug 21, 2005
  4. richard.ingall

    Muck Guest

    Unless this is some clever play on words I don't know about... It's a
    roller bearing engine isn't it? What other bearings did you replace? Did
    you fit them properly, as in not tap the bearing in with the inner bit?
    Are you sure you got the cam timing correct? Did you check the valves
    for straightness? Did you rebore / fit a new piston?

    Completely rebuilt? What does that mean anyway?
    Muck, Aug 21, 2005
  5. Roller bearing crank, YTC. It's just possible the alternator isn't on
    the shaft properly - that can make an unholy din if it's a bit loose and
    or wobbly. Sounds just like a fucked crank as well - ask a Ducati owner.
    The Older Gentleman, Aug 22, 2005
  6. had the same thought myself last night, will give it a shot to see if
    there's any wobble on the alternator later today

    richard.ingall, Aug 22, 2005
  7. Also check for a loose clutch center nut and make sure the carbs are
    Grimly Curmudgeon, Aug 22, 2005
  8. richard.ingall

    Muck Guest

    It's a single.
    Muck, Aug 22, 2005
  9. Cheapskate.
    Grimly Curmudgeon, Aug 22, 2005
  10. richard.ingall

    Muck Guest

    Some singles need their carbs ballancing though. :) Didn't some versions
    of the XBR500 have a twin carb type setup?
    Muck, Aug 22, 2005
  11. You still don't "balance" carbs on a fucking single, YTC. The idea of
    balancing is to get all the carbs on individual cylinders on the same
    The Older Gentleman, Aug 22, 2005
  12. richard.ingall

    Muck Guest

    Ok grandad.
    Muck, Aug 22, 2005
  13. Cheeky young whippersnapper.
    The Older Gentleman, Aug 22, 2005
  14. richard.ingall

    platypus Guest

    XT600/SRX600 were dual-carb singles - IIRC one was a slide and the other a
    CV type.
    platypus, Aug 22, 2005
  15. richard.ingall

    Lozzo Guest

    The Older Gentleman says...
    I bought a GPZ1100 with something similar wrong for **** all money
    once. It cost me a temnner to fix.
    Lozzo, Aug 22, 2005
  16. richard.ingall

    Lozzo Guest

    Muck says...
    Did they do a 10" dub mix?
    Lozzo, Aug 22, 2005
  17. richard.ingall

    platypus Guest

    I was more concerned about him impugning the holy simplicity of the XBR500.
    platypus, Aug 22, 2005
  18. richard.ingall

    Muck Guest

    Drum and bass, no, that's Ducati isn't it?
    Muck, Aug 22, 2005
  19. richard.ingall

    Muck Guest

    I thought some versions of the XBR had a different carb setup? Mine was
    simpler than most XBRs, only having 3 of the 4 valves working. :)
    Muck, Aug 22, 2005
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