Vision speed wobble...?

[Rikugun]

If your bike wobbles when you take your hands off the bars, don't consider it a problem with your bike. Alot of bikes wobble when you remove your hands from the bars as they provide damping that keeps the bike from wobbling. You can work endlessly and never get rid of it.

Yup  :)

[Lucky]

Visions don't have this problem initaly, they develop it...

I think they have the makings of it right from the factory and the right road conditions, riding habits or one or more mechanical parameters slightly out of sorts will manifest the wobbles.

this is a new condition for the bike. road conditions & riding habits have are not caused by the bike, "mechanical parameters slightly out of sorts" are what needs to be checked. I have to ride the bike & see if it will recreate with my 230lbs on it. if so it's likely the bike. neither Spectre or i have experienced it on this bike before. 

Now it is possable that it could be rider induced, he's much more comfortable testing limits than he used to be..
Both Tourer or Cafe are rock solid at any speed, I haven't gotten Kittys bike roadworthy yet...

True any bike can wobble if the conditions are correct, what i'm saying is I wouldn't classify the Vision as prone to it.  some have experienced it, most have solved it, but it's not a cronic stator or carb...

[fret not]

This sounds like a prime candidate for a steering damper.  It doesn't take much resistance to quell oscillations, just enough to upset the resonant frequency.

[Rikugun]

There have been some good suggestions of things to check and I hope you get it sorted out. That's a good point about Spectre's growing confidence is now challenging the bike and symptoms are only now being revealed. So be carefull Spectre until you get to the bottom of this!  :)

[AdvRich]

Spectre in the meantime, get a bar mounted bobble head to use as an early wobble detection system. "Wow! look at that grass skirt go..." Mind the speed son, mind the speed...  :D   ;D

[Rikugun]

Wow! look at that grass skirt go

When I suggested Spectre get to the "bottom" of this, I didn't quite have that in mind... :D  :)

[Lucky]

I could see both the grass skirt & shmohawk wobbling! lol!!

[VisionMeister]

I was thinking about this problem and scrolled back throught the comments and noticed no one suggested checking wheel bearings.
Put the bike on the centerstand and get the front wheel off the ground and check for play.
Also spin the wheel and visually check the front tire for runout.

The Vision has very quick steering geometry and is very sensitive to tires and road surface conditions and ride height, hence the comments about slow speed front end wobble with no hands.

Front end ride height can be effected by sacked out fork springs, improper fork oil level, improper fork or tire air pressure, and tire profile (80 vs 90 aspect ratio or 100mm vs 90mm or combination of the two).
Front tire:
90/90 stock = 81 mm tire height
100/90 = 90mm tire height ( a huge difference, muck slower steering/ less tendency to wobble. This is probably what the majority of Vee owners use).

Rear tire:
110/90 stock = 99mm tire height
120/90 = 108mm tire height (raising the rear, lowers the front and quickens the steering)
120/80 = 96mm tire height, slightly less than stock

You can see that using a 120/90 rear with a 90/90 front would need adjustment to maintain stock steering geometry
120/90 rear with a 100/90 front raises both ends the same and is very close to stock steering geometry

An overly sprung or preloaded rear shock can also yield a higher rear and quicker steering front.
Ron McCoy told me when he was racing, he used to always chaek the rear ride height first when the bike wasn't steering.

My Vision was steering very slowly (very stable) for years after I installed the Fox shock. Then one day,when I was riding with Supervision, we noticed the rear was about on inch low in comparison to his V. I lowered the front by moving the fork tubes up in the triple clamps and the quick steering returned. I have played with this several times since, especially when changing tire brands or sizes. You can lower it until it wobbles or is oversensitive, and then raise it slightly. 2-5 mm's can make a big difference here.

Good luck finding your problem

[treedragon]

Has the front wheel been balanced??

It is a must, XZ wheels are never in balance.

I have survived a high speed tankslapper on an XZ years ago, dinted the tanks it did. Balancing the front wheel stopped it.

[Lucky]

good info guys!

[munkyfistfight]

The symptoms I've experienced in this area apply only to slightly loosening my grip at certain speeds. If my hands are on the bars on a straight line at 80mph there's no wobble or vibration whatsoever. The bike is super smooth, actually. It seems only to occur at a certain speed if I let the grips loose briefly (to lift my visor or whatnot).

Now, with mine...the bike had been sitting for over a year so I can't say that there might not be some distortion in the tires from sitting. I do have a fork brace as well. I'm about to put brand new tires on this season, so I'll update accordingly

[Rikugun]

I'm about to put brand new tires on this season, so I'll update accordingly

I realize this is a different phenomenon than Spectres' speed wobble but I'd still be very interested in your update.  :)

When I first noticed mine doing this it was probably as you described messing with my visor or a vent zipper on my jacket. I experimented a bit and feel it's worse going downhill. I'm not sure if that's due to weight transfer and/or increased effect of engine pulses through the drive train and rear wheel? On flat ground it doesn't always do it immediately but will start if I attempt to steer by weighting the pegs. Once initiated, it escalates scary fast but will be calmed instantly by just a light touch of the grips. 

[don_vanecek]

Having had my Vision from brand new I have to agree with the statement this wobble develops over time, I can remember many times the first couple years going any speed I wanted and never having a wobble then somewhere I think after maybe 20000 miles I started to get that 80 mph scare which was not too appreciated as the Vision will easily hit 80 passing on two lane roads.

I changed the bearings but you know what, it STILL wobbled. I was really fooled as to how much more I ended up tightening the new head bearing before viola, no more head shake.

That was my experience.

[VisionMeister]

Overtightening the bearings is the equivalent of a friction damper.
Lots of old bikes had friction dampers as standard equipment. Triumphs had  them.
I owned a Vision "new" from the dealer as well. The pathetic stock front tire would speed wobble at the slightest variance of conditions, road surface, cresting hills, hard braking, low tire pressure (2lbs would do it).
Also, the stock, overly sprung shock made sure the rear end was always too high, at least for my 180 lb weight at the time. Now that I'm 215 lbs I could probably compress it enough to slow the steering.
My first tire change was to a 100/90 front 120/90 rear (1985 Pirellis) and the stability gained inspired confidence to "ride it like I stole it".

[spectre]

Sorry of the late reply guys, I've been really busy between work and school :p but summer is coming soon, so I'll have lots of time for testing and tune ups. I wish I could find the problem before our trip to the dragon, but it's not a BIG big issue ATM. My tires are new avons with 1-1500 k miles (I ride every day as its my only transportation) I have also noticed that my V seems to pull to the right slightly with no hands on the bars, now I have MACs and I'm hoping to goodness that it's just the weight balence throwing me off, we had my bike down to the frame and we didn't see Any cracks, or rust at wield points, wrinkled paint, ect. If I do have a bent frame, it sure would explain my wobble issues haha. I'll see if I can make sure my wheels are true. I appreciate the help guys, I'm hoping for the best.

[Rick G]

I don't worry about the head shake . If I keep one finger on the grip it doesn't happen. Since I almost never ride with out at least 1 finger on the grip , its of no concern.  I occasionally ride with one or the other hand off of  the grip , to rest my hands (arthritis)  it's always under control.

[spectre]

A steering dampener you say? That's an interesting idea... Does anyone know anything about this sort of thing? Are there generic ones that will just bolt on? This seems like a job for google.

[Lucky]

I have no problem with you adding a steering damper but lets fix the cause first instead of curing the symptom..

[Rick G]

Modern road racers have some type of hydraulic steering damper. The old friction dampers on , Triumph , BSA, Matchless , AJS, Sunbeam, Norton , Et all, were more trouble than they were worth. A steering damper is supposed to control head shake when your hands are ON the grips. If it doesn't shake, when there on the grips, you don't need one!

[dcsob]

I'll weigh in. Looked through the posts. Are you sure all frame to engine fasteners are tight to spec? My understanding of engines as stressed frame members has lead me to check the bolts/nuts for any looseness. I've even loosen and re-tourqe to rule it out with weird speed wobbles.
Are you sure nobody slipped some mercury in your tire when you werent looking? :o