SV Head Shake

Early Saturday heading out of Masham for Hawes up Wensleydale I had a huge head shake (10+times lock to lock) from the SV after hitting a bump/hole I hadn't spotted between 75-85 mph. Luckily I was heading in a straight line (and there was no traffic) but only just managed to hold on to the bars and keep off the verge. Needless to say the sphincter was twitching and the adrenal gland secreting.

This is the first time I've had this happen on the SV in two years, is this just a one off due to the bump?

The bike is standard susp/geometry, apart from not hitting the bump in the first place is there anything else I could have done (in addition to hanging on)?

[DarrenSV650S]

That doesn't sound good at all!
I had a minor slapper when my front wheel lifted on a hump a few weeks ago. Got a bit of a fright and was wondering whether it was worth while getting a steering damper ?

[squirrel_hunter]

There are 2 schools of thought about what to do in the event a a tank slapper or head shake. You either close the throttle or open the throttle. This will either add weight to the front and stop the wobble or take weight off the front and stop the wobble. Opinion on which to do is divided.

My thoughts are by the time you get one its over to quick to react, though I have found that I seem to keep the throttle constant when I get one (best of both worlds I suppose!). I mainly get them hitting a bump at speed under hard acceleration as the front is already light, but have got smaller shakes taking corners at 120mph+ though I did get a very violent one off a cats eye once that shifted the front brake pads causing them to bind.

If you worried about it most would recommend a steering damper.

Yep I was accelerating at the time and think I was just finshing changing gear at the time, so had the drive hitting as I hit the bump. It was all over so quickly I've no idea whether I throttled on, off, or kept it constant!

Had the odd minor twitch over bumps before but nothing like this, although perhaps better observation would have helped me out. Going to stay off a steering damper unless this type of thing starts to happeen more often.

Me too! Last year, overtaking a car on a B road, accelerating hard in 4th, front wheel skimmed off the bevelled edge of a catseye and it did a headshake for about 1 1/2 seconds. Nothing too serious, and I kept the power full open. I will consider a steering damper if it happens again.
Jon.

i feel this on the thou when cornering fast but the damper fitted as standard just makes it a minor shake, ive never had a bad one.

[DarrenSV650S]

Can anyone recommend a damper or a rough price guide?

it shouldnt really need one or it would have one as standard, slow down and avoid pot holes and you should be ok

[embee]

Apart from the obvious things like tyres, I'd first look at the head bearings.

Anything with a castor (which is what the front end of a bike is) can be unstable under the right (or wrong) circumstances.

I need to do my SV, I can feel a slight instability. Reading the manual, the standard cup/cone bearings (nothing fundamentally wrong) need quite a lot of preload, more than you might think. I serviced my Hondy a few weeks ago, and the spec for those is much the same, and I found the lockrings were only finger-tight instead of the 25Nm bearing preload specified in the book. It's certainly sorted the front end of that out nicely, much more precise now.

Dampers only control the symtoms, they don't cure the disease. By definition they only have an effect when there is already movement.

I'm no suspension expert but i got my first big shake on the sv last summer after about three years and 15k on a piece of road i have ridden many times. I was reckoning it had quite a lot to do with the rear shock getting old. The forks were stock but about 5k old after a kind german forgot to look were he was going.

Havnt been able to see if it got any worse because the gearbox blew up very soon afterewards and then i went travelling so the only shaking the had has done in the last 8 months has been on and off the paddock stands grrrrrrrr.

Were your tyres squared off?