GS 1000 ST : the weave is back

[tatu]

Chris, what tyres and pressures are you running?

Tyres are Avon Roadriders
Front: 110-80-17 22psi
Rear: 150-70-17 20psi
Since I dropped the pressures the weave has gone and hasn't returned, though I have always been ready for it to come back but so far so good.

Mine was a very strange effect where if you were leaning into a turn and the road undulated such that the rear spring compressed more than the front the bike would lay down into the turn but come back up as the spring rebounded.

So high speed turns above 60-70 mph could be a little spooky at times. Below that there was not the same rear spring compression that seemed to manifest the feeling.

I theorised it was rear sidewall flex exceeding front side wall flex due to the banked turn while compressing the rear more.

I had all new bearings,alignments everything so it had to do with springs and tries and nothing else.

The weaves the S,es have develop even in a straight line, over the years a couple of really scary tank slappers with a couple of utter terrifiers when cranked over at flat chat.
I found out on the first day I ever rode my first 'S that trying to throttle through it makes it worse. When it got paniky bad the way I ironed it out was to sit bolt upright catch as much wind as possible and ease off the throttle till it was back under control, you could then wind it back open and not a hint of weave.
Thinking about it now, I have never experienced a weave two up.

 

[Kiwi Canuck]

Tyres are Avon Roadriders
Front: 110-80-17 22psi
Rear: 150-70-17 20psi
Since I dropped the pressures the weave has gone and hasn't returned, though I have always been ready for it to come back but so far so good.

Wow those pressures seem low, but if that's what works then who's to argue.

I am running the stock rims and went with stock 3.25 19 and 4.00 - 18 Avon Road Riders, they are 100% profile as you probably know.

I'm running 28 PSI front and 30 PSI rear, so I will try lowering them to see what changes it makes.
Mind you I don't ride fast enough these days to induce a big tank slapper or get into much trouble on the big corners.
Also I love my "S" too much to risk laying it down, I rather have chicken strips on my tires, than road rash on my Cooley.

 

[Frank Z.]

Ah yes, the nauseous weave wobble. Have had some relief from lower tyre pressures (thanks tatu), and went back with a fork brace. Still comes on when wringing her neck, esp. through the power band when the front end lightens. Will also get twitchy approaching 100mph... then i move my arse back about 6", light touch on the bars, and push it through. Never a rosy feeling, but working at the moment.

So, i've adopted two types of riding: around town high on the tank, and the Hailwood tuck for fast flights.

 

[Kiwi Canuck]

You most probably used racing slicks with a much lower profile than the /90 used on the street bike.
John Ulrich wrote in a Cycle World test of the Yoshimura GS 1000 "When I rode the Suzuki at Riverside it wobbled fiercely, yet at Willow the handling was faultless"
A strange machine the GS 1000 S but what a pleasure when you get it right

John, I was production racing on the "S" so we ran DOT tires and they were likely stock sizes, with 100% profile.



I do remember one time during open class practise, David Hiscock came flying by at the end of the front straight at Ruapuna on a GS1000S Yoshimura special and immediately got into a big tank slapper right beside me, that was pretty exciting for me and I'm sure he had big eyes for a while.

 

[John Kat]

John, I was production racing on the "S" so we ran DOT tires and they were likely stock sizes, with 100% profile.



I do remember one time during open class practise, David Hiscock came flying by at the end of the front straight at Ruapuna on a GS1000S Yoshimura special and immediately got into a big tank slapper right beside me, that was pretty exciting for me and I'm sure he had big eyes for a while.

It reminds me of me racing a Honda 750 Daytona in the 70's with Dunlop K81s
The bike was like a truck but when you unloaded the throttle going downhill in a 100 mph corner, it would start a slow weave until...you opened the throttle again to stabilize the machine
Jarno Saarinen was there in the GP category on a Yamaha TZ 350 and his machine also went into a belly dance in the same corner but...just a little faster