SV Head Shake

[northwind]

Originally Posted by Luckypants

Only ever got a headshake from the SV after hitting a cats-eye hard on the gas. This was AFTER fitting upgraded shock / fork springs / emulators.

Yep, if you hit an object under power it's going to happen sometimes, really, unless you fit a damper- just one of those things that'll happen.

I've never had one on the SV but had two on my old CBR.

They were so violent that I could not keep hold of the bars. The more I tried to regain control the more violent it got. In the end I let go of the bars and looked for a good place to get off. Letting go of the bars and the front end sorted itself out enough for me to regain control.

The first was on landing after taking air time over a railway crossing and the 2nd was hard acceleration out of a corner. The 1st one was on a straight road and I hardly moved one side or the other. However I think the traffic on the other side of the road must have been having kittens.

The 2nd I regained control but had drifted towards the edge of the road. I spent the next 100 yards fishtailing the back end in the gravel trying to get back on the tarmac.

I took the bike in to the garage (didn't do own servicing then) and they confirmed that the head bearings were worn. Got them replaced and never had an issue again.

Well since the event I've been chatting to a mate who's an ambulance driver up Wensleydale, and some of his colleagues who ride bikes have said there are a couple of notorious "hidden" bumps on a couple of the straights, so don't think it's just me.

There are loads of big humps up there too which are pretty fun, even I occassionally get the front wheel up.

Ive only ever had two on the SV and one was quite bad, i hit old train tracks inbedded in the road at a place called stanton near me, it was a Tank slapper to say the least and very violent! i knew if i closed the throttle i would go down again, so i cracked it open and it just stopped and corrected its self.
Oscilation 0 - Jon 1 !!!

2nd coming down the A52 hit a cats eye and my bar spun to the left and almost put me in to the trees! managed to lean it back in to the road but it was a propper brown trouser!
Oscilation 1 - Jon 1

How common is this problem on the SV? I have to say reading this and being new to the SV makes me slight nervous?

Originally Posted by danf1234

How common is this problem on the SV? I have to say reading this and being new to the SV makes me slight nervous?

Don't be nervous.

The only time I've ever experienced a head shake on the SV was after I'd played with my suspension settings. I was also riding the bike too hard for the road surface I was on (ie, full throttle acelleration, 2nd & 3rd gear coming away from a roundabout, there's a dip & a left bend, the road surface is uneaven coming up out of the dip).

Mine developed a head shake about 1500 miles after a new front tyre was fitted. Had front wheel re-balanced and it was a mile out apparently, perfect now though.

Hey,

I was beaked when I posted that I bought a Scotts damper. It's saved me before and I wouldn't hesitate purchasing another.

Mitch

[Taipan]

A lot of the time head shake is inadvertently down to the rider and poorly set up suspension.

What happens is you hit a bump which makes the bars move. The rider then tries to stop or correct this, but there is no way you can match the forces equally. So what happens is you transmit a weave through the bike. This is can escalate dramatically to a full blown tank slapper and even end up lobbing you off! A steering damper can keep this under control but a ride can't.

Thing is, if you weren't lent over and could let go off the bars it would right itself immediately!

If you're bike tends to weave or feel like it hinged in the middle frequently, especially when acelerating out of corners, then it’s normally down to an incorrectly sprung or badly damped rear shock. On a fully adjustable rear shock you would dial in some more rebound damping to counter this.

Ill matched suspension also creates weave. People often upgrade the front suspension without altering the rear. They should be balanced. Best bang for buck on any bike is properly set up suspension. The Sv isn't a full on sportsbike and has real crappy budget suspension. Tis a chink in its armour maybe, but to be fair to the SV its suspenion is inline with its price.

[embee]

I've just put some different clip-ons on my SK1.
http://forums.sv650.org/showthread.php?t=87711&page=3

While about it I stripped the steering head down. The lower bearing was almost dry. Fully greased the bearings, reset the preload (just enough to feel very slight resistance with the wheel off the ground), and fitted some 0.85kg/mm linear springs from K-Tech in Coalville, Leicestershire, with Motul 10W oil.

Before this overhaul I was feeling the slightest hint of wobble at certain speeds, and I'm sure the bearings were too slack. Since doing the overhaul it's steady as a rock and feels a world different, totally transformed.

If as you say you're on standard suspension, consider some springs and servicing the head bearings. Wish I'd got round to it years ago.