What causes a speed wobble (high speed weave)

[Mitch]

That's a funny looking chain there

 

[razz]

Steve , how you getting on with sorting out your weave ? I hear you took the demo bike out , and that it does not weave , mine is in today having the upgrade adjusters fitted , and no doubt ady / Aran , will make sure she's 100% in line . Did you head back to HMT ? Lots of questions indeed , hope ya well and enjoying the heat

 

[stevecbr]

Not sorted yet, I have complained to Bridgestone and am awaiting their response (been waiting a week).
Been back to HMT, everything checked, laser aligned wheels, all seems ok but starts to wobble at 100 and get steadily worse, I darent go over 110.
HMT suggested it could be mechanical, or a trait of the bike. Thats why I took Tinklers demo down the Watton Rd, and that was fine (but felt slower than mine)
Still no ideas of what it could be, even took of mudgaurd extender to check it wasnt that (its not)

 

[MT account]

i have a nasty speed wobble on mine now n i can tell you exactly when im doing 102 (kph officer) without looking at the speedo as the bike instantly goes into the start of a tank slapper. its caused by my luggage. i guess i just need to tour slower.........

 

[marthy]

i have a nasty speed wobble on mine now n i can tell you exactly when im doing 102 (kph officer) without looking at the speedo as the bike instantly goes into the start of a tank slapper. its caused by my luggage. i guess i just need to tour slower.........

Crank the rear preload. My FZ6R front end was getting light like that fully loaded.

 

[marthy]

Hummm? What kind of tire psi are you using? I got mine as fast as it would go few time at the track and that thing was rock solid!

 

[MT account]

Crank the rear preload. My FZ6R front end was getting light like that fully loaded.

oh its cranked right up there.........must be down to the airflow over these bags

.........although i got the same (but bigger) on the other 1 and that doesnt weave....same settings, different tyres.

 

[marthy]

Running oem suggested tires psi. Like 36/42?

 

[MT account]

Running oem suggested tires psi. Like 36/42?

oddly enough the FZ was usually around 32 front and 38 in the rear @ 30 degrees c (cold). and it didnt wobble.

 

[marthy]

Im running 30/30 cold.

 

[MT account]

maybe it likes a bit more tyre contact on the road? i will lower the MT tyres and see what happens......can always blow em back up!

 

[marthy]

Thats what I think is going on. Tire psi are too high and the tire run too cold to have enough grip... and tire patch too small.

From what I found on some reliable site, tire psi should go up 10% at the front from cold to hot (30-33) and about 20% on the back (30-36). Start at 30/30 and give it a good 30 min ride to get them stabilized and check them hot. I usually end up around 33/35ish hot.

I think that should help a bit.

 

[stevecbr]

I have been advised to run them at recommended pressures, 36 front and 42 rear

 

[MT account]

I have been advised to run them at recommended pressures, 36 front and 42 rear

thats what i have in my MT and it weaves like a bastard. my FZ was last checked at 34 f 38 r and that handles fine at the same speed. the only other difference is dunlops on the MT and 023's on the FZ

 

[stevecbr]

Are you running bt023,s and the handling is fine?

 

[MT account]

Are you running bt023,s and the handling is fine?

well heres the thing, i ride both bikes exactly the same but the 023's sit fine on the road, it doesnt get out of shape easily, it feels fine going deep into corners and the pressures are set a bit low. the dunlops are at the right pressure, it squirms under power, the front feels very unsure at speed but fine into corners. of course its 2 different road surfaces and even 2 different pressure gagues im using so maybe not a definitive test!

 

[marthy]

I have been advised to run them at recommended pressures, 36 front and 42 rear

I have the same recommended psi on my FZ6R and the bike is 80 lbs heavier. The chain free play is suppose to be 5-15mm to... LOL

Just like in real life, going by the book usually get you just so far. If the bike wiggles, lower the psi and get some heat in the tires.

We are recommended to follow speed limit and keep the front wheel on the ground, how does that work for you [emoji6]

 

[MT account]

I have the same recommended psi on my FZ6R and the bike is 80 lbs heavier. The chain free play is suppose to be 5-15mm to... LOL

Just like in real life, going by the book usually get you just so far. If the bike wiggles, lower the psi and get some heat in the tires.

We are recommended to follow speed limit and keep the front wheel on the ground, how does that work for you [emoji6]

i think it also says not to loon around in forests but since when did i do what the book tells me to do?..............
TBh i coulda benefitted from 10psi in the back tyre through there...........

 

[stevecbr]

Teckie guy from Bridgestone rang me today.
He went into lots of technical detail about tyre force, resonance, harmony etc and lots of stuff I didnt get.
The long and short of it is the S20 is approved for use on the MT09, the BT023 and T30 havent been tested, or on their list of approved tyres for the MT09. He is aware of the fact certain tyres dont suit certain bikes, as appears to be the case with the BT023 and the MT09.
He suggested i try the T30's (at my own expense) and see if thats any better. I obviously replied I didnt fancy forking out £250 to be their geuini pig and testing their tyres for them, I would use a brand from another manufacturer.
So, moral of this story is DONT FIT Bridgestone BT-023 to your MT09, unless you never go over 100mph!
I will be posting a new thread, to see what sport touring tyres work with the MT09

 

[Kinjane]

Have you checked wheel alignment? The OEM Dairylea wedges aren't that accurately marked, and whilst the deformation doesn't look too pretty it's the hole in the middle of the block that positions the spindle, not the spindle head bump stop, that's only there to stop the spindle turning.