I'm referring to my GS500, posting here to get some advice from disinterested parties, as the gstwin forum couldn't really give me any clues.

Standard tyres all good, have added heavy duty front wheel brace replacing standard brace. all bearing seem to be in good condition, no notchiness or play.

Sometimes I can feel it if I'm going round a low speed corner and hit a dip in the road, otherwise it does not manifest itself at all unless I force it.

You may say 'well don't force it then'. But the problem is that it did not do this for the first year and a half. It will occur under these circumstances... if I am riding along in a straight line at any speed and remove my hands from the handlebars, bike will track in a straight line if I then give a not very hard rap on one side of the bars, it will immediately set up an oscillating tank slapper that I have to kill very quickly because it's plain to see that it's gets bad fast.

If it did this from when I first got the bike I would not care, but the fact that this appears to be a new problem bugs me. It does not cause any problems, no stability issues as speed or in corners but the fact that it can get going so easily worries me, in case I hit an unseen bump or hole at speed.

The only clue I have is that if there is weight on the back, either a passenger, or 10kgs in my Givi rear case then giving the handlebars a whack does not induce the wobble.

There are no suspension mods, it has standard rear shock, I weigh about 65kg. Does this sound like perhaps the rear shock could be causing this? Perhaps it's croaked?

Try this --- it costs nothing and may point to the source of your issue.

Get on the crown of the road and get the bike tracking nice and straight & smooth,  then turn loose of (or allow the front end to float with very very very light finger contact so you can feel tugs and shakes).   Do this at your "normal issues discovered speed".

Note if the handle bars are offset any at all when eyeballed square to the tank and the frame of the bike.    People are surprised to see their front end is running down the road tracking crooked .....

If so, it is telling you the rear axle is out of alignment to the frame of the bike by the exact same amount and direction as you noted the handle bars to be.

Go home and straighten up the rear axle and get the chain/belt all properly tensioned (and yes, those rear axle index marks are often off quite a bit as swing arms are not always true any more and your frame can actually get tweeked a little bit).

The front end always runs perfectly in line with the rear tire axle adjustment.   Physics says this must be so or else you'd go skidding along down the road slightly sideways wearing your tires out really really fast.  

Adjust the rear axle to make both issues go away, and likely your wobble will too.

Tugs and shake motions that are in time with wheel rotation say your wheels need some truing by spoke adjustment.

There is a spanner nut "tension adjuster" on the front stem on many Suzuki bikes (Savage included) and the spanner itself is included in the tool kit.

It is possible that a fork brace can be over tight and cause some stiction in one of the fork tubes...
That'll give you some wobble.

I'd try removing the brace.

It's not the brace because I was hoping the old brace would solve the problem which predated it. The brace is just a rectangular piece of thin steel, the new brace is identical in positioning and is simply lighter and about 4 times the thickness. It's not a brace that clamps the forks but rather goes over the fender which is plastic and not rigid like the s40 fender.

I'll be trying some of the other things suggested later today and report back. I was hoping that weight on the back in my rear carrier solving the problem might be a clue. Also the front wheel 'howls' when turning a corner which it never did, although the tyre seems fine.

I do use a laser alignment tool to make sure the chain is running square and the tool is butted up agains the rear sprocket. I have not noticed any pulling to one side but I'll do a more sensitive test later today.

IslandRoad wrote on 05/05/18 at 17:07:46:

eau de sauvage wrote on 05/05/18 at 19:03:29:


I am currently running Bridgestone Battlax BT45 tires, and the front tire has square blocks on the edges.  The blocks on the edges wear uneven from aggressive cornering, and now when I lean the bike over the front tire sings like crazy.  This doesn't seen to affect the handling - but the front tire tread really doesn't work for my riding style and I am going to try something else........my front tire wears out long before the rear tire.

How old is the front tire....there is a 4 digit date code on the side of the tire - old tires can ride really poorly.

My only experience with a wobbly front tire was on a Honda ST1100, and if I let go of the handlebars at slow speeds the front forks would wobble badly.  A new tire fixed it.

Have you checked to see if the swing arm and rear wheel are tight?

This is what I was thinking too.

  Tighten your steering head bearings a schoosh. With the bike on the center stand, put weight on the rear to lift the front wheel off the deck.  The steering should not flop to either side.  It should slowly turn to one side or the other with a touch to get it off center.  If it flops quickly to the side, the bearings are too loose and you are at risk of a tank slapper.  Very bad thing, it can wreck your bike and even kill you.  Tighten a little at a time until the steering does not flop to the side.  If you are running a sidecar this is especially critical and you should also have a steering damper.
I adjust mine to no flop and I can take my hand off the bars at cruising speed. Then I install the steering damper for insurance.    

Its easy enough to check .

................................

The tire replacement is a strong posibleity too !!!