S4 Ohlins SD154 problem

[Kato]

Well clearly the cure for headshake is to stop at 119mph problem solved

[Mr Gazza]

+1 for Kato's suggestion, or roll off even earlier than that.

In the late 70's early 80's I rode a lot of contemporary Bonnies and Tigers back to back.
They would nearly all start a Dutch roll at exactly 98mph, not a shake or dangerous speed wobble as such, but with varying intensity depending on how quickly you got there, passenger present, road surface and so on. It would settle if you pushed through it. (But not much left @ 98 to be honest!)
I noticed that the UK spec bikes with flat bars did not do this and attributed the phenomenon to aerodynamics. The US or export bars were quite high, so I think it was something to do with the wind rolling off one side or other of the torso alternatively. Much as a flag will flutter in the wind, or a loose jacket?
In your case it might be something to do with a headlamp fairing or screen if you have one, or maybe a mirror on one side only? I imagine you already have lowish bars?
Have you tried just bending your elbows and tucking in a bit when the wobble starts, or preferably just before?

[jerry]

Originally Posted by Mr Gazza

+1 for Kato's suggestion, or roll off even earlier than that.

In the late 70's early 80's I rode a lot of contemporary Bonnies and Tigers back to back.
They would nearly all start a Dutch roll at exactly 98mph, not a shake or dangerous speed wobble as such, but with varying intensity depending on how quickly you got there, passenger present, road surface and so on. It would settle if you pushed through it. (But not much left @ 98 to be honest!)
I noticed that the UK spec bikes with flat bars did not do this and attributed the phenomenon to aerodynamics. The US or export bars were quite high, so I think it was something to do with the wind rolling off one side or other of the torso alternatively. Much as a flag will flutter in the wind, or a loose jacket?
In your case it might be something to do with a headlamp fairing or screen if you have one, or maybe a mirror on one side only? I imagine you already have lowish bars?
Have you tried just bending your elbows and tucking in a bit when the wobble starts, or preferably just before?

tried it all Gazza , had this bike for 18 years now ,, bars are flat, no fairing , lowered forks 10mm very good suspension with full adjustment both ends ,tried every possible geometry etc 2 mirrors, tried every possible body position including flat on tank,

only thing I never tried is a steering damper , which was a reccomended fix by numerous people on Older monsters flightiness and wobles at high speed ,

I have been stubborn as new fitted a damper to any bike i rode in the past , solved them other ways , and my 750 monster is stable at 115mph ish but of course the S4 has 50hp more and the front end always feels lighter than any other bike I have ever ridden in last 50 years ,, My modern Z900 feels very solid and planted at 130+ mph but its not as agile a missile as The S4

[jerry]

im back in UK and just got an email from Ohlins dealer in Bangkok seems Ohlins may have assembled some damper wrong and stamped them with wrong code ,, but its all older stock ???

I will try to pick up a damper set while in Europe but im not paying £500+ spo looking at other makes, hyperpro, Ktech etc they seem around £300 a set

[jerry]

Originally Posted by Kato

Well clearly the cure for headshake is to stop at 119mph problem solved

yes mate thats what I do ,, tried riding through it , not fun at all, but im good at sensing it so just back off a tad but I hate not solving issues ,,