Help with 2007 VFR 800 Engine vibration problem

Discussion in '6th Generation 2002-2013' started by roadracerSL02, May 27, 2013.

  1. roadracerSL02

    roadracerSL02 New Member

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    Hi there

    I am a new VFR rider. I bought myself a beautiful 2007 25th edition used 2 months ago with only 26000km on it. The previous owner put on a scorpion exhaust and a K and N filter. I have driven the bike for two months with zero problem. It was a smooth as can be and sounded amazing. The acceleration was smooth as butter and I would describe the exhaust note as like a purring tiger while cruising. Smooth sounding.

    Two days ago something changed. I filled the tank with fresh fuel and started out on a morning ride. About 25 minutes into the ride I began to notice a buzzing kind of vibration in the bars in the seat and in the foot pegs. Not the normal VFR kind of vibrations but something I could only describe as like holding on to a jigsaw or buzz saw. Under acceleration its becomes worse. The entire engine has lost its smoothness and even the exhaust note has changed. It no longer sounds smooth like a purring tiger but rather it sounds like a buzz saw coming from the exhausts. There is no mistaking it. The entire acceleration note has changed to a buzzy kind of sound and the bike vibrates like mad under acceleration. I should also clarify that strangely nothing has changed about the power delivery. The bike hasn't lost any power that I can tell and still pulls strong and hard as ever. I should also include that the bike is difficult to start in the mornings or if its been sitting for a while. It wont fire on the first or even second crank. It takes 5 or 6 cranks to get it going. When its warm it fires instantly on the first crank.

    The bike does not have a power commander but since this issue is new in the last two days I dont think the issue is related to power commander or tuning.

    I replaced the plugs a month ago.

    Does anyone have any idea where I should start with this problem. Does it sound electrical? Spark plug related? Ignition wire related? Timing related? Could it even be caused by bad fuel?

    Any help would be great!
     
  2. jethro911

    jethro911 Member

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    That is quite disturbing! It does sound like the onset of the issue coincided with a fresh tank of fuel so perhaps it would be advisable to drain the fuel and get some fresh gas from somewhere else. Wouldn't that be awesome if that was all it was! Too easy? Yah probably.

    The starting issue sounds like a problem with the throttle bodies, perhaps the starter valves. Maybe something came loose and went out of adjustment. Have a look at this thread as it will help you become familiar with the system and perhaps aid you in locating the issue.

    http://vfrworld.com/forums/6th-generation-2002-2009/28233-starter-valves-synchronization.html


    Good luck and keep us posted
     
  3. skimad4x4

    skimad4x4 "Official" VFRWorld Greeter

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    Hmm

    The refuel may be just co-incidence. Assuming the tank was fairly empty then the new stuff would swirl around in the tank and have mixed extensively with the old stuff, and I would have thought that any quality issues would come to light within yards of leaving the filling station not suddenly after 25 minutes of happy riding.


    I have a few ideas on what might cause the symptoms you describe, but without more information its very much speculation and could be down to a heap of things.

    If one cylinder was not firing, or getting fuel it would make it feel very rough, but should be down on power. There are other weird things which can cause vibration like a tight spot in the chain or losing an balance weight from a wheel, both can make the bike feel wrong but not really affect power. I am sorry I think you really need to do a bit more investigation. If you say there was a buzzing - can you locate the area where it is coming from? Were there any other symptoms? Have you got any MIL warning, blown headlight bulbs, strange instrument behaviour?

    Also worth checking your battery volts are healthy and also volts at idle and at 5,000 rpm - as a failing battery or charging issues with those bikes are known to cause all sorts of issues.

    Keep us posted.



    SkiMad
     
  4. Mohawk

    Mohawk New Member

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    There's not info to go on really, but based on the info available I'd do the following.

    1. Check your oil, both that it has enough/some & suck some out to test its viscocity.
    2. Drain & replace fuel from another source !
    3. Check all plug ends for fuel burning & look down each plug hole to check piston crown state, for wet state or debris etc.
    4. Check that all plugs are inserted correctly & have their ignition coils connected properly.
    5. Check for any loose items in the drive train.

    It's not clear if you do or do NOT have a PC3. If you do, then try disconnecting the PC3.

    Vibration is normally caused by one of two things. Either a mechanical fault, i.e. something has failed broken or come loose. Or by an ignition/fuel issue where one or more cylinders is NOT firing at all or correctly.

    Hope that helps.
     
  5. Scubalong

    Scubalong Official Greeter?

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    Vibration................Have you check your tires pressure?
    Did you clean out the air filter?:rolleyes:
     
  6. czakky

    czakky New Member

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    I dont want to thread jack here, but my bike is basically suffering from the same issues (04 26k). In my case it is clearly an engine issue as I can feel it in neutral stopped when revving. My thought was starter valves?? again sorry to thread jack here
     
  7. roadracerSL02

    roadracerSL02 New Member

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    Ok so I decided to start with the battery. Took it out today and it was the original. Took it to have it tested and sure enough it was pooched.

    I don't know if this will solve the problem. In fact I can't see the battery causing any problem with ignition good or bad. However some have mentioned that a bad battery can cause all kinds of unexpected problems with this particular bike.

    Keeping my fingers crossed and will keep you all posted.

    If anyone. Can help me understand how a bad battery could cause problems other the hard starting specifically related to how the engine is running and the ignition I would appreciate the information.

    Thanks all
     
  8. roadracerSL02

    roadracerSL02 New Member

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    Ok Update. I replaced the battery with a brand new one. Although the old battery was pooched the new one seems to make no difference to the problem at all.

    To really simplify and clarify... a few days ago suddenly the engine went from being smooth to being very buzzy. Both the feeling during acceleration and the sound coming from the exhaust is most like a buzzing sensation. The bike still pulls like a rocket. I cant tell if its misfiring or not but it feels like a misfire only not nearly as bad.

    Any other ideas?
     
  9. czakky

    czakky New Member

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    mine is a pretty pronounced buzzing from like 5500 rpm and on.... is yours about the same??
     
  10. MrSleep

    MrSleep New Member

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    My vote is mechanical. Upper engine. Since you say the engine sounds different. You can go two ways: pull your hair out tearing everything apart checking it OR just ride it till it gets worst and maybe easier to trouble shoot. Just my 1 5/8 cents.
     
  11. MrSleep

    MrSleep New Member

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    Do a compression check and see if anything comes back abnormal.
     
  12. Maggot

    Maggot New Member

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    Cheap and Easy. Pull your air filter and see if anything is loose or rattling around in your air box. Mice have been known to make nests in here.
     
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