High Speed Vibration?

[galen]

I mounted my own tires a few months ago and used Dyna Beads to balance them. Now at any thing faster than 98mph i start getting strong vibration from the front end.It is strong enough to make me let off of it. Everthing is fine at other speeds and lean angles. It was the first time i have mounted a motorcycle tire but i have mounted other types.I am starting to think its the beads. Any ideas would be great, it is 166mi round trip(3hours each way) to the closest bike shop.

 

[youngy]

You could build your own balancer...... a frame with a pair of roller bearings on each side that the spindle can sit on.

Spin the wheel. See where it stops. Add some weight. Spin again until the wheel doesn't stop in the same place.

A friend of mine has one and it works fine.

Might be worth a try if you're that far from a bike shop.

 

[flash]

I am a little sceptical about hose dynabeads, how do they know to always go to the light side of the tire?

 

[TownsendsFJR1300]

I've checked the balance/balanced wheels just using the axle thru the wheel bearings in a jig I made up. The jig doesn't use any additional bearings, it just basically holds the axle with 2 upright "V" cut groves.

You could also use your forks after removing the calibers and loosening the axle (no drag on the wheel/tire). The axle bearings should be loose enough to allow the wheel to rotate if out of balance...

The static balance should show if the wheel is out of balance or not. Pay attention to the rim and outer tire as well to make sure nothings bent/out of round...

Good luck..

 

[Shamus McFeeley]

I've used dynabeads for the past 2-3 years on several bikes, so has my riding buddies, never had a problem. Are you sure that you used the correct amount?


Flash, this is how they work:
Dyna Bead FAQ

This is the formula you are suppose to use:
R1 = Inside Radius
R2 = Outside Radius
W1 = Weight installed on rim
W2 = Weight of Dyna Beads needed.

W1*R1 = W2*R2 to calculate the actual weight of beads needed.
(3)*(8) = (x)*(12)
24 = 12x
x = 24/12 or 2 oz.

 

[galen]

I used the amount that was spec for the tire size,2oz rear and 1oz front .Should i add more to the front?

 

[FZ6-ZN]

I’ve got two sets of rims and tires both with dyna beads. I’ve pushed my bike to its max with the race tires (power one’s) on the track; no vibrations. The other set (power pure’s) no vibrations on the street up to 180km.

Stick on weights tend to fly off at high speeds, so I prefer the beads.

 

[galen]

How much did you put in the front?

 

[tjhess74]

i know these things are a controversial topic, but i too have used them in the past with no issues. the bike wasnt a sportbike, but did see the occasional triple digit. i too would double check to make sure you have the correct amount in the tire. if its a new tire, dont rule out a defect in it. of course the easiest way is to remove the beads and run it.

being that far from a tire shop, you should invest in a harbor frieght tire changer (or similar). a friend and i went in on one and over the years has saved us a ton on tire changes.

 

[galen]

So i hade the tires ballanced by a good shop and the vibration is still there. Changed the stearing stem berings and it is All better:thumbup: Lower bearing was toast. Finaly :BLAA:

 

[ohgood]

So i hade the tires ballanced by a good shop and the vibration is still there. Changed the stearing stem berings and it is All better:thumbup: Lower bearing was toast. Finaly :BLAA:

hmm, so the vibration (you can only balance as close as the measuring device) set up an oscilation that increased at X mph, hmmm

did you feel any play in your forks with the front end off the ground ?

how long since bearing adjustment ?

was the bearing adjustment via the fsm, or "feel" ?

glad you have it fixed

 

[galen]

hmm, so the vibration (you can only balance as close as the measuring device) set up an oscilation that increased at X mph, hmmm

did you feel any play in your forks with the front end off the ground ?

how long since bearing adjustment ?

was the bearing adjustment via the fsm, or "feel" ?

glad you have it fixed

At first check there was no play at all and that was a few of months ago. I think it may have gotten worse over the last couple of months and i started to feel a click in front end under hard breaking. Inspected again and had a lot of front to back play. I will start cleaning/repacking the bearings every other yr now.I have only had the bike for a little over a yr now and it was all stock but was not maintanied all that well. I have found little things once digging in that shows prev owner was lazy or not capable of reg mantinance.

 

[stbrnrd]

similar issues - except that the front wheel has been removed and rebalanced after the initial findings - and had no difference in the results of the vibrations -
I'm experiencing strong vibrations at the handlebar between 98-119, slow at 98, strong at 110, less to vanishing as the speed increases to 119. it isn't "road conditions" have tested in many different roads to verify the findings. my concern is that it could lead to something else or major breaking while riding. i don't normally ride that fast, but sometimes speed is needed to maneuver through obstacles, but i don't need it to rattle the bejisus out of me while doing so. the vibration itself is kind of cyclic (rut-tu-tu) about every 2 seconds and lasts about a second, and the front tire has been checked and rebalanced, all the bolts have been checked, the brake disk as well has been inspected, the caliper, fairings. ran out of things to look at...just asking if someone had a similar issue....and what could possibly be the issue or root.
2006 FZ6
21000 miles

 

[FinalImpact]

Is the suspension stock? When is the last time the fork oil was replaced and what weight of oil? Stock springs?

FWIW; It worthy to note that a toy top which is balanced well and not subject to road variations doesn't need any damping devices to happily spin vibration free until it runs out of moment....

Point is at 120mph your front tire is clipping along at 1709 RPM so the balance better be pretty good. Potentially the variance of weights on the side vs balance weights dead center in the wheel could make a difference.

Back to damping; between tire carcass stiffness and suspension damping; once a bump or dip puts an oscillation in motion the damping system needs to control it. If it can't, this is what you get. A rhythmic oscillation.

Assuming the balance is pretty close.. .. ..
Changing tire pressure, springs, fork oil to a different viscosity, or tire itself to a stiffer or softer carcass (air pressure can impact this too) could impact the speed this happens at as well as the severity.

FWIW: the rear would be @1,626 RPM at 120mph based upon a 24.8" dia w/a rollout of 77.9" / 180, 55, 17"
=)

That said, the front has to travel 4.8% further! :welcome:

 

[TownsendsFJR1300]

A little more info please...

Is this a new front tire, if not how old is it?

When did the problem first arise? After any maintenance, tire change, etc? Mileage on the tire?

Sounds like it's the tire so far... Any cupping/flat spots on the tire?

Probably not the issue but easy to check, lift the nose of the bike and check for triple tree play. On the center stand, jack under the header and get the ft wheel up. Then try to lift the wheel/forks up and down feeling for any play...

And no, you shouldn't have any vibs at that speed.

Did you double check the balance? Inspect the tire closely as well for ANYTHING unusual, any bulging on the side walls, etc..

 

[dbldutch02]

Just to go back to the OP's issue, and solution - I've had the very same thing recently, horrible vibes through the bars at anything over 95mph - had the wheel balanced (twice), then at the MOT they said my headstock bearings needed tightening. I was sceptical as it it didn't feel wobbly, but I did them anyway - the bottom bearings were bone dry and full of crud. Bit of a clean, bit of grease, reassembled and the vibes are completely gone, and a mystery rattle I'd been chasing, and the backache I'd been getting recently too. Seems they got bad so gradually that I didn't notice.

Happy days