vibration problem on a 3rd gen

Discussion in 'Mechanics Garage' started by Joh89, Jul 24, 2013.

  1. Joh89

    Joh89 New Member

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    I bought the bike a few months ago and it rode beautifully at first. After roughly 2000 km, my right hand started to numb from vibrations. The whole bike vibrates but only my right hand suffers from it. There's also a mild shimmy in the steering at certain speeds that would take the bike down if I let go of the handlebars.

    I have had the front wheel balanced, the tire seems ok though it has 7000-10000 kms on it. I've changed the front fork oil, I've retorqued the engine mounts apart from the lower through bolt. The idle is a little unsteady but the engine runs smoothly when throttle is applied and accelerates like brand new. The front wheel and steering stem bearings show now sign of wear.

    I am in need of suggestions and tips as I am getting tired of the numbing.

    The vfr is -91 with 107 000 kms on the clock.
     
  2. Bryan88

    Bryan88 "Official" VFRWorld Greeter

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    That's pretty high mileage for the tyre, possibly it's worn unevenly? I know nothing of wheel balancing, but I would think that although balanced weight wise balancing wouldn't help with irregularities on the outside where it touches the road. Just a thought.
     
  3. YAUGURU

    YAUGURU New Member

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    Can be only one thing
    Tyre
     
  4. squirrelman

    squirrelman Well-Known Member

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    When's the last chain/sprocket replacement ?? The last head bearings renewal ?? Not saying it's a factor, but why not fix the unsteady idle ? Make sure the 2 tank side buffers haven't gone missing.
     
    Last edited: Jul 24, 2013
  5. zoom-zoom

    zoom-zoom Insider

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    My last bike was a 97 VFR750 and I had installed heli-bars not long after purchasing the bike. After a few months I noticed the same hand numbing vibration coming through the bars. I removed the bars and controls and taped over the positioning holes for the switch gear with electrical tape and then reattached. I then filled the bars (heli-bars were hollow though I'm not sure if the stock clip-ons are as we'll) with sand blasting media sand. I measured the length of the screw that holds the bar end weight in place and filled the bar cavities until the sand was just about up to the end of the screw by using a small screw driver to gauge how much sand was in the bar cavity. Hold the bar with the bar end weight up and use a piece of paper rolled into the shape of a funnel to get the sand in the hole. With the control bar upright I then reinstalled the bar end weight and reattached the controls. The reason for holding the bar upright is so the sand doesn't get jammed up in the threads (make sure to remove the bars and hold them upright any time you have to take the bar end weights off after doing this or you will destroy the threads when the sand gets stuck). I rode the bike for nearly five years (sold the bike just before my son was born) after doing this and the vibration in the bars went away almost completely and my hand wouldn't get numb even after 5 hours of riding.

    The mod took less than 15 minutes per side and all you need to do is undo the bolt on the clip-on and remove the c-cllp retainer at the top of the fork tube to get the bars off, but you don't have to undo anything. Having a friend hold the bars while you fill with sand is really helpful.

    Not sure what might be causing the shimmy in the front end but as others have said the front tire is likely due for replacement. You might also want to check the steering stem head bearings as they might be worn as well.
     
  6. squirrelman

    squirrelman Well-Known Member

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    Usta use B-Bs to damp bar vibes, but sand should be useful too.
     
  7. Joh89

    Joh89 New Member

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    Thanks for the quick replies.
    I'm gonna try the sand trick this weekend.
    Front tire change is gonna have to wait for next month.

    Steering stem head bearings may be rather old.
    Chain and sprockets are nearly brand new and tank side buffers are well in place.
    For the unsteady idle - I haven't been able to locate the problem. I cleaned the carbs, checked the valves and replaced the air filter for only slightly improved performance.
     
  8. ridervfr

    ridervfr Well-Known Member

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    :worthless:

    My Gen 3 bike is sensitive to front tyre wear, if you take your hands off the bars at low speeds when the tyre has a 5000 miles or so, you get a wobble, (who takes their hands off the handle bars anyway!)

    Tyre tends to wear un-even as the roads have crowns and such. Try a new donut, if you jack up your bike under the exhaust system and get the front wheel off the ground, you can see if the bars flop to either side without much force, think pinky force. You should not get a self centering in the middle as this means there is a divit. Steering head bearings are a nice item to change on a 25 year old machine btw...AnywhooOOOOoooooOOOOOOoo----Hi Ice-Hunchin :wave:
     
  9. Joh89

    Joh89 New Member

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    Well as it turns out, the handle bar weight had fallen off without me noticing. I tested with a set of weights but they were too light i'm guessing. Still the numbing only occured in the right hand. Gonna test with heavier weights or sand... later.
     
  10. ridervfr

    ridervfr Well-Known Member

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    If my bike farted, I would know it as its been with me for a long time, kinda like "the first wife." I know when she farts too :tongue:

    I had some lousy bar ends on my bike for a while and when a Honda scooter came in, I decided to swap them oot, they were the same ones that originaly came with the bike, I had someone who made custom frankenstein bolts do the bar ends, turns oot, you really need a heavy piece of metal to dampen the vibes. The new bar ends work perfect. Live and Learn, Ride to Live, Live to Ride...
     
  11. Joh89

    Joh89 New Member

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    The heaviest I've found are 190 grams, which doesn't seem like much. I'm gonna make them myself and get the kind of weight that definitely makes a difference.
     
  12. squirrelman

    squirrelman Well-Known Member

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    Stock OEM head bearing sets are almost always well knackered by about 35,000 miles and crying for replacement.
     
  13. Joh89

    Joh89 New Member

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    The bars are filled with sand and new weights installed. There is an improvement but it didn't work quite as effectively as hoped for.
    The wobble can be explained with a worn tire and\or worn bearings, but the vibration issue still remains.
    I can pull the clutch at high speeds and lose all vibes thus showing they originate from the engine. What are the most likely things to cause this? Slack in the engine mounts? They are torqued to the specs apart from the lower through bolt in the rear
     
  14. ridervfr

    ridervfr Well-Known Member

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    I dont think I ever put a spanner on any of the viffers motor mounts. I did lose a nut off a kawasaki after a motor oot motor in scenerio, then it was red-lock tite and everything is good.

    everything has vibes, its just the way it is. Was next to a HD at a traffic light and the fellows skin under his bi-cept was shaking, looked like chicken...
     
  15. jimjam

    jimjam New Member

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    if the vibes go when the clutch is held in the first thing I would check is exhaust mounts . after building many of my own bikes and installing custom made exhausts it has shown me that a simple mounting rubber can transform the bike. The exhaust shouldn't really be physically touching any part of the frame unless it has a rubber bush
     
  16. Joh89

    Joh89 New Member

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    Exhaust mounts...I added a rubber bushing to the silencer mount by the rear wheel. Better check the rest of them. How about the connection to the cylinders? Surely there's physical metal-to-metal contact?
     
  17. jimjam

    jimjam New Member

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    yes there is but the engine and its mounts are holding that pretty tight, the tubing of the exhaust and the can resonate and the farther away from the motor the more chance of vibration .
     
  18. Joh89

    Joh89 New Member

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    Yeah I just realized how pointless my question was. The strange thing with the vibes is that only my right hand numbs. I can feel it in the left hand but it's with no agonising consequences.

    Another thing I would like to improve is wrist ache. Due to the riding position, too much weight lies on my wrists. With a low windscreen it's hardly a problem but after an upgrade to a vario touring screen the wind resistance is far too little even at high speeds. Seems like the touring feature is utterly useless. I will go back to standard screen if no help can be found.
     
  19. jimjam

    jimjam New Member

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    mmm whats the higher screen like ??? I am 6foot 2 inches and find the standard screen blows straight into my neck so I am after a higher/taller screen . I had an excellent tall screen for my zzr that was £15 from hong kong but I cant find any cheap ones about for the vfr
     
  20. Joh89

    Joh89 New Member

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    I bought the touring screen used for 75 euros. I am 186 cm and the wind hits right about the middle of my visor. Pull it up at 100 kph and you're blind in a heartbeat. Pillion feels no wind at all and anything below my helmet is a no wind zone. The vario feature doesn't seem to make a difference regardless of the positioning of the adjustable add-on which supposedly throws wind over your helmet. Might work for a child...
     
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