High Speed Wobble (630)

[organ donor]

Appears around 120km/h and has been noticeable on the bike since it was new. Now on its second set of tyres and has got worse. Tyres are well balanced and I´ve tried different pressure settings but the "wobble" always sets in at the same speed. Amplitudes then increase with speed and improve with power reduction. Think road surface has some relevance and have managed 160km/h (once). Have also experimented with front suspension height and rear settings. All to no avail. Any ideas?

 

[badbowie]

May be a long shot, but are you running any sort of rear bag? It has be found on some bikes that a rear bag has caused high speed wobbling

 

[WHITEROCKET5.9]

stering stabilizer?

 

[organ donor]

Excuse my ignorance ... but has it got one?

 

[WHITEROCKET5.9]

honestly i dont know, was just throwin it out there. im sure someone with a lil more knowledge than me will chime in on this.

 

[kevinperry]

My 630 is fine on the motard wheels ....not so good on the knobby tires on the highway . I would bet a steering stabilizer would fix the wobble at speed.

 

[organ donor]

ok think I´ll just have to try one out ... any ideas?

 

[kevinperry]

Maybe this one?? .....

http://scottsperformance.com/Stabil...ID=5628&Year=2011&Size=630&Fred=&BI_ID=148391

 

[glangston]

I've had my TE250 (2008) up to 70 mph (120kph) and no wobble. Newer knobbies on typical city street.

Think about re-setting the forks and axle. Test by seeing how easy the axle slides in and out of the front wheel.

Here is my dealer's story on forks and axles. Not saying this is the cure for the wobble, because right now, no one knows.

"Now that the debate on torque values is over.??? When you set LH fork leg heigth in the clamp Do Not think the other side will be the same, get it close then set it by how the axle goes in. You might have to either lower or raise it, so the axle goes in smooth. You can usually see it hitting the top or bottom of the axle hole on the LH side. Once you get the axle to just slide gently from one side to the other it is lined up properly. Now one side might be up or slightly down on the rings this is ok and it is right. You can tell if have to use palm of your hand or mallet to get the axle thru the forks when putting front wheel on. Later George
After the forks are installed to the correct heigth(where you want them), where the axle slides thru nicely, torque the clamp bolts both sides upper and lower to specs. With wheel installed and axle nut tight, thighten lower fork leg axle pinch bolts on the LH side( making sure the grab bar on the RH side of the axle is not touching the fork protecter)now slam it into a wall then tighten the axle pinch bolts on the RH side.
If while riding and you smack anything log, rock,get caught in a rut where you've dragged the lower leg, or rubbed it hard just loosen the pinch bolts and give it a good smack into anything solid to realign it on the axle. I think this is main reason other than dirt contamination fork seals wear out and leak. Later George

 

[organ donor]

What would the world be without help from Cafe´ Husky! Many thanks (the main dealer here ... Zupin ... was no help at all). The Scottsperformance installation guide is very comprehensive ... but it looks complicated! Will start on the front legs of the beast and let you know how it works out.

 

[moto66]

Try lowering the forks in the triples. Most guys seem to run the SM's with two or three rings showing over the top of the top triple clamp. This is great if you're tracking the bike but for street use flush with the top of the top triple will give you the best straight line stability.

 

[robertaccio]

do all the usuals in addition to the mentioned, balance wheels(been there), wheel bearings,check steering head bearings are snug and or not beat up (been there), check chain for tight spot (stretched) (been there). fork projection as mentioned, sag setting so the rear sits right. check discs have no warp or bend. good luck

 

[rajobigguy]

There is one more thing to consider, rider induced wooble. I'm not suggesting that you are new to riding or anything like that but sometimes if you're on a bike that you're not very intimate with or one that you are uncomfortable at speed with there might be a tendency to ride with a little to tight of grip on everything. If you are riding to tense you can actually induce a wooble youre self. Are you completely relaxed at speed? Really you're hands should just be resting on the grips, if you're fighting it you'll never win and just make the situation worse.

 

[oneleven]

When my bike was still breaking in I tried to find max speed on the highway. Got to 160km before I backed down with some left to give. No wobble at all. Since then I've modded it with a Lynx fairing, HDB guards, PU/airbox, rear pegs removed, and stock mirrors. Also I lowsided it on a wet road at speed a month ago. The guards took the brunt of the force, but the forks twisted enough to skew the steering. It was fixed by banging it back straight against a wall. And the bike was lowered a couple inches two weeks ago. So now I've got about half the tread remaining on my original karoos. Went for another spirited ride on the highway a few days ago and I experienced wobble for the first time at 140km. Dry day, no wind. Another 5-10 klicks faster and it became scary. I slowed down and tried again but this time I relaxed my grip. The wobble was still there, but not as pronounced. Got up to 154km before I backed down to a more relaxed speed. I'm thinking it's the Lynx, but the windshield was all the way down. I'll have to take a look later at my front axle.

 

[organ donor]

Correct, I know about the grip and tried to just touch the bars with my fingertips. Can´t be the steering head, spacers, warped disk etc as the bike´s new (and had the wobble from the start). Am starting to think it might be induced by the duck-bill front fender. It sets in at almost exactly 120 km/h and (I think) on really well surfaced roads (German autobahn), so could also be induced by very slight ripples on the road surface. Forks are set as per initial delivery right at the top. (could lowering them improve matters?). Think a damper might just override the problem without solving it.

 

[brock]

Set your rear sag and set your forks through as mentioned earlier. See if that helps. If it wont go away stick a Steering Damper on it www.werproducts.net, they are a CH sponsor too!

 

[pvduke]

drop fork
increase for comp damp
increase rear sag
increase shock rebound damp
check front spokes/wheel brgs/axle torque.

what type tyres and road surface are you duplicating this on? some tires follow grooves on concrete roads more than others and there's jack you can do about that. doubt it's doing tank slappers or youd be on your head at that speed. PIO can't be ruled out either.

 

[jtemple]

I would get some wobble on my old Motoz tires at those speeds, but really only on grooved pavement. The MT21s have done well in the same situation.

I have no steering damper.

 

[rajobigguy]

Correct, I know about the grip and tried to just touch the bars with my fingertips. Can´t be the steering head, spacers, warped disk etc as the bike´s new (and had the wobble from the start). Am starting to think it might be induced by the duck-bill front fender. It sets in at almost exactly 120 km/h and (I think) on really well surfaced roads (German autobahn), so could also be induced by very slight ripples on the road surface. Forks are set as per initial delivery right at the top. (could lowering them improve matters?). Think a damper might just override the problem without solving it.

Absolutely right, a damper will make the ride nicer (I love my Motosportz damper) but you shouldn't use it to mask a problem. Even though the bike is relatively new you still might have an issue with steering head, or other, bearings being bad or ill adjusted.

 

[organ donor]

The main dealer here in Germany got back to me and advised lowering the rear suspension by two turns of the knurled ring 8increasing rear sag). As it´s a fine thread, the change was minute, so took it out to the autobahn and the wobble set in even earlier (114km/h). So `phoned Zupin and was told to try the opposite.Have done that but haven´t been out at speed yet. It does now feel more sprightly while cornering though. If this doesn´t work, the steering head is next on the list. And then the front forks.