Advice sought. Instability at moderate speeds

[FROSTY:Me]

Just one little thing to try when ya get the weave ixion--try dragging a little bit of back brake --it might stabilise the whole plot ---its an old XJ riding trick

[Ixion]

Tried the rear brake feathering trick , it's one I've used on Briddish twins, but it didn't help. If a new front tyre doesn't do it I think I'd next turn my eye to the front suspension as suggested by Mr twoseven. Definately not soft tyres that was one of the things I was testing at the weekend. Pumped 'em up real hard then tried repeated runs dropping the pressure 2psi each time. No difference (not to the weave, at any rate). But the K75 does have a softish front suspension. and of course that's a hellish heavy fairing on it.

Found a stretch with a couple of bumps placed so I could induce it reliably. Definately nothing detectable at 145kph. At 150 or a fraction over hitting the bumps sets it off. It's not actually frightening, just a slow gentle weave , no sign of developing into a tank slapper and throttling off or braking to under 140 stops it.I tried seeing if it would ride out at higher speeds, but it was still there, no better or worse at 170 which was all that I had road for. Not quite like instability I've had in the past. We'll see what a grooved front does, I have a lot of faith in grooved front tyres.

[Ixion]

Well, the Metzler front tyre finally wore down enough that I could replace it with a clear conscience (I could probably have got another 5000k out of it, but it was near enough that I could tell myself it was time to go). So I've replaced it with a Continental.

And, by chance today, following a Rocket 3 (hells bells, those things are impressive), I found that the problem is indeed resolved . Glanced at the speedo, and somewhat to my surprise found that the bike was rock steady at 110 somethings per hour ('twas indeed 110 - I'm not saying what units of measure, make your own surmises).

So I'm considering the case closed. It was the cruddy Metzler, as suspected. Certainly no sign of instability at the original speed , and I so rarely visit the far side of 180 kph that I'm not going to bother checking any further. Big tick to Continental TKV11 and TKV12.

[Bonez]

So I'm considering the case closed. It was the cruddy Metzler, as suspected. Certainly no sign of instability at the original speed , and I so rarely visit the far side of 180 kph that I'm not going to bother checking any further. Big tick to Continental TKV11 and TKV12.

Thanks for sharing. What type Metzeler where they?

[Ixion]

Thanks for sharing. What type Metzeler where they?

ME33 I think. I suspect the BMW is one of those bikes that really needs that longitudinal groove, like on the old Avon Speedmasters (ah, now there was a tyre !)

[Bonez]

ME33 I think. I suspect the BMW is one of those bikes that really needs that longitudinal groove, like on the old Avon Speedmasters (ah, now there was a tyre !)

Don't you mean IS a tire - http://www.americanmototire.com/inde...arget=d84.html

[Motu]

You can get Speedmaster's in race compound too,not a tyre to be taken lightly.I used to scuff up mine half way down the bloody sidewall,scary stuff.

[Ixion]

But , radials ? and tubeless ? But I will very seriously consider them when I replace the 'orrible tyres on Petal. I think they even come in the right sizes. Phoebe has Michelins, which seem quite nice. But I never had a bad experience with Avons.

[sels1]

And, by chance today, following a Rocket 3 (hells bells, those things are impressive.

If you think they look good, wait to you ride one. I managed to get a couple of test rides and they are an amazing machine. lampost blurring acceleration
and yet easy to ride around tight twisty (Wgtn) suburban roads. Good brakes and suspenders too.

Good to see you got your prob sorted - I will file that bit of info away for future reference.

[Ixion]

... lampost blurring acceleration
,,.

I noticed. I'd just gone past a Harley, and the Rocket 3 went past me with contemptuous ease - and hardly revving at all.