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Yamaha XV250 Engine vibration

Discussion in 'Technical and Troubleshooting Torque' started by loader, Sep 7, 2005.

  1. Can anyone suggest some common causes of excess engine vibration in a Yamaha XV250 twin? it sounds like theres a little knocking/tapping from the rear cylinder, possibly valves?
    And in certain revs it really resonates in the whole bike.
    Could it be the valve clearances?
    Am i correct that the timing chain doesn't need adjusting on a virago
    Any suggestions would be great as I'm dumbfounded

  2. Valve clearances alone are unlikely to "resonate the whole bike", unless they are so far out it's mis-firing. I don't know much specific to the XV250, but a worn small-end would give the symptoms you describe.

    Is it there all the time at all rev's/speeds?.....does it increase and decrease with engine revs when the bike is in neutral?
  3. Your auto cam chain adjusted could be shot. Pretty common on a lot of bikes. Not sure about virago's. Not sure if there is a manual replacement available for it either.
  4. i ride a SRV which uses the same engine as the XV250. dont know if this will help but i had the same problem. i had to ride gently to stop the vibrations in the footpegs at certain rev bands.
    i had put the normal unleaded fuel [i think it is 93 octane?]. once i switched to 95 octane fuel and the vibrations became a lot less noticable. i am going to try with 98 octane and see how that works.

    also someone advised me to get the bike serviced as i had bought it without any service records. i did and it helped but not very much. i hope this helps.
  5. Take the cards and pegs off the spokes!!! :p

    Nah seriously, I used to have one of these treasures, but sorry but I can't help.
  6. The motor only has about 15000km on it so I don't think the cam chain or adjustor should be shot yet. The vibration appeared about 2000km ago and seems to be steadily getting worse.

    The vibration hits at higher revs when I twist the throttle when she's in neutral. It causes other things like the speedo to buzz. Could this buzz be caused by the valve adustment, or likely something more serious inside the motor.

    Could it be anything to do with the carbies and how they are set?
    I will definitly try some 98 octane and see if that helps.

    still open to any suggestions

  7. Could this have anything to do with the condition of the engine mounts??
  8. Clutch in or Clutch out?? Could be a simple as the clutch. Mine used to make a knocking sound when the clutch was out in neutral.
  9. It may need a tappet adjustment.

    I doubt it has hydraulic lifters, but if it has, one may be stuck.

    Is it constantly there and increases with revs? or comes and goes across the rev range?
  10. Mine makes a similar noise - I assumed a stuffed baffle in the exhaust, since it varies with the revs.

    Must do the bafflectomy a-la groberts on it one day... oh wait, I'm getting rid of it soon. May not bother...
  11. The vibration increases with revs. it hits a peak when it vibrates the petrol tank, silencers, headlight etc, then subsides a little when I continue to increase the revs. Unfortunately the peak vibration occurs in the middle of the rev range at around 60kph around town!

    I don't think it's the tappets as I had the valve clearances checked about 3 months ago with no change in the problem.

    Could it have anything to do with ignition timing? Would the cylinders being ignited slightly out of time produce such a vibration??? :?
  12. Yes/no.

    It would tend to do it under load.

    Does it vibrate like this if you just rev it standing still?

    Here's a thought. Are both cylinders firing? i.e. hows the power/
  13. Yep, she still vibrates when standing still, under no load.

    Also the power is fine, at least for a 250.

    Am starting to think it's the cam chain, or maybe I should check the valves again just in case it wasn't done properly last time
  14. Take it to a good mechanic.

    It could be a few things, but with the bike in front of them they should find the problem fairly quickly.
  15. You wouldn't know any good trustworthy mechanics apart from the guys at the BMW dealership would you????
  16. Not off hand. A few have been mentioned on this site in the past, so a search might pull a few up, alternatively perhaps somebody could let loader know of a good mechanic.