Hi Guys, after some advice on a problem that has me a bit stumped, Kawa GPZ 500 front end wobbles e.g. bars start to flap from side to side, only happens at slower speeds (under 4 thou RPM in top), Checked wheel alignment, tyre pressures, front disk not warped, tyres are worn, head bearing checked by centre stand method, not snagging or falling to one side. If it was a wheel bearing would it happen at all speeds, sometime get a judder while braking with front stopper, any other suggestions. Cheers - Greg

When does it wobble? If it wobbles most under deceleration or when you let go of the bars your steering head bearings are too loose. Most road bikes are prone to this after they have a few miles on them (maybe a few hard landings after those wheelies?). If you want to check the bearing tightness snug them down till you get some resistance to the bars turning with the front wheel in the air. If you get them too tight the bike will weave at slow speeds. Try it and see. Some people will say you have to use special tools and neutron ounce meter torque wrenches but just proceed with caution and see if the wobble gets better or worse with your changes.

Thanks Bill I will give it a try and see if this improves the situation, I will report back once the spannering has finished!!

Cheers

Greg

try the balance of front wheel- or make it done for you. some whigft adjustments may help i think.

As I understand you get a resonance in the steering (around steering axis) with a frequency of a few wobbles per second. It is usually only a mild wobble but gets worse under braking and the wobble goes almost end to end if you let go hte bars. This can be caused by a worn front tire and the specific thread pattern alone (means it does not occur with every tire). Some bikes (sports with small wide front tires are specifically prone) develop it even with new tires and all patterns. As far as I remember it is referred to in English as shimmy effect and closely related to kickback when riding over a hard, short bump while cornering.
First thing to do is to replace the worn front tire. This will most probably sort the problem.
If you check your steering head bearing the center stad method only reveals a bearing that is too lose or extremely worn / rusted. If the lower bearing is only slightly worn (enough to give trouble) you will have to try and feel the bearing while under load. This is done either with a rotating support pan as used for wheel alignment in cars under the front wheels or a similar device specially made for bikes.
Alternatively you can ride the bike very slowly in first and you will feel the steering "locking" in the center and the line being somewhat difficult to keep.

Do not fiddle with the steering head bearing unless you know what you are doing. The chances that you bugger the bearing are good compared to getting it right.

Checking the wheel bearings is very easy. Ask someone to show you or check in a standard or type specific motorcycle mechanics manual.

The judder under hard braking is a resonance of the front fork. Pretty normal. Frequently seen in heavy bikes with long front suspension travel (like older Transalps and A.Twins)

Hi guys thanks for the advice, however my woes continue as 4 weeks before I am due to do a six month bike trip some silly old sod reversed his car into the bike last week and knocked it off the side stand!

Broken fairing & bent exhaust!. Now I have the joy of arguing with insurance companies.

My vote is also for worn front tyre , to test whack 5-7 lbs extra pressure in it and see if it improves.. usually the extra pressure will cause you to run in a different part of the tread. Is a cheap quick thing to do.