Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Honda CB250 front wheel wobble @ 60km/h

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Mr Flibble, Apr 21, 2008.

  1. G'day

    I've only been riding for about 6 weeks, and this is my first bike.

    Yesterday, I noticed that if I decelerate with only a loose gripe on the handlebars the bike starts to wobble violently at around the 60km/h mark. A bit unnerving to say the least! It comes good when I tighten my grip, but surely this isn't normal behavior?

    The tyres seem good to me, no sign of uneven wear (bugger-all wear actually). Bikes done ~18,000km, 2001 vintage.



    It was in a fall Easter Monday - I keep it in the carport which has compressed clay floor. Two days of steady rain made the floor a bit soft and the side stand sunk in. Doh! Needed a new clutch lever, and RHS mirror stem and the base of the RHS mirror stem broke as well - ie the front brake assembly (brake fluid reservoir). How the hell it manged to bugger both the LHS and RHS is beyond me.

    I wonder if this could have caused it, and can the fork alignment be checked/fixed?

    Thanks / Regards
     
     Top
  2. Checked your tyre pressures lately?
     
     Top
  3. Yes I check the pressure every day - its always OK. Sorry, should have said.

    Regards
     
     Top
  4. You don't know whether it would do it before the "accident" so I would surmise that the two events are not related. It is not an uncommon issue.

    Possible causes:

    1) Loose/worn steering head bearings

    2) Tight steering head races (that's another name for the steering head bearing assy.)

    3) Insufficient or too light oil in the forks (damping is not enough)

    4) Poor tyre pressures - are you checking them cold before you ride, with your own gauge? What sort of gauge, pencil or dial type.

    5) Worn swingarm bearings.

    6) Poor quality rear shocks - insufficient damping (unlikely to cause this but...)

    7) Worn wheel bearings or loose spokes.

    8) Wobble or dent in front or rear rim

    9) Wheel out of balance (quite likely) or uneven tyre wear because forks have been misaligned for a while.

    To check the forks stand to the side and look up and down the front and back edges of the fork tubes/fork legs.

    They should be in line (looking from one side of the bike to the other)across the front and the rear edge. If they are out of line on one edge they will, of course, be out of line on the other. If the bike has had a minor drop it is easy for the forks to receive a slight twist which is easily fixed.

    Another way to see this is if the wheel is pointing straight ahead as you ride (that is, you are going in a straight line) and the handlebars are pointing a little to one side or the other.

    10) Don't ride with your hands off the bars, or gripping them lightly. Under decelleration the fork/steering head angle steepens which quickens the steering and can make some bikes feel unstable. This does not mean you don't have a problem of some sort, but that in normal use you should still be safe.

    All the best

    Trevor G

    Please ask questions about any of the above as required.
     
     Top
  5. Fat chance :wink: Its good fun.. :)

    +1 to that list, obviously check pressures and look more closely for uneven wear.. Then balance wheels, and when you get that done they you can check if steering head bearings are nackered.. can be detected just by moving it around if they're totally stuffed - I believe.
     
     Top
  6.  
     Top
  7. I am, but you can totally do both at the same time :wink:
     
     Top