Vibration above 50 MPH - Yager w/ only 350 Miles

[Zimmerman]

I bought this 2010 Yager with only 295 miles on it.
I've gently put 50 miles on it as it still needs to be broken in and I'm getting to know this scooter.
( I've logged many hours on Riva 180 & 125 as well as People 150.)

This Yager scoot has significant vibration at 50 to 60 MPH.  I've not gone over 60 MPH yet.
I guess the vibration must be 'up/down' or a general vibration because I don't feel it side to side.

It does not seem to be RPM related.

I don't feel it particularly in the steering.

Has anyone had this type of problem, and how did you isolate the cause?

I wish I could run the scoot on some type of Dyno-belt so I could see what's happening . . . For now I'll have a few friends look at the wheel while I'm driving the scoot.

Kevin

[Zimmerman]

I just saw this info about dyna beads balancing tires.

Is there any down side to trying this ?

http://www.innovativebalancing.com/motorcycle.htm

[MotoRandy123]

Sounds like tire balance to me. They are balanced at the factory, maybe you threw a
weight? Or one tire could have a lump in it (factory defect).

At certain speeds mine gets harmonic rotating vibrations but they go away at
faster or slower speeds. That's just the nature of a scooter I think.

Not sure a local shop could/would balance them for you. The bike is covered by a 2 year warranty
though my dealer is a tiny shop with no balancing equipment that I could see. Bring it to a dealer
and maybe they would put a new tire on (or balance it). (if it's still in warranty).

Dyna beads work for some people. Motorcycle Consumer News did a test of them a while back
and determined they did not do as good of a job as a "proper" balancing. They would be difficult
to get into the tire. I have trouble getting my air pressure gauge on those stems.

 One last thought. The suspension might be oscillating. Try adjusting the rear preload stiffer and
see if it changes anything.

[Zimmerman]

Randy,

That's a good idea - I'll adj the suspension & pst the results.

Kevin

[CROSSBOLT]

I vote for a wheel out of balance although you did not say specifically the vibration was road speed related only 50-60 mph. I have good experience with Dyna Beads in scooters and related similar products in motorhome tires. Remove all factory weights before you put Dyna Beads in. The trouble with stick-on weights is they can and do fly off.

Karl

[Zimmerman]

Yep - the vibration starts at 50 MPH and continues up to 60 MPH.
I've not yet driven the scoot faster than 60 MPH, as I still breaking it in.

The vibration is not noticeable at any speed lower than 50 MPH.

I'll order dyna beads but try a few things while I wait for them to arrive.

It would be nice if the beads fixed it, but even if they 'change' the problem then that will confirm it's a tire balance issue.

Kevin

[Zimmerman]

Adjusted Rear Suspension - Vibration Changed
----------------------------------------------------
Suspension Adjusted - Vibration Changed
----------------------------------------------

I adjusted the suspension as MotoRandy recommended.

It was at the 'lowest' setting which allowed the spring to uncompress as much as possible.
I assume the dealer [or previous owner] set it that way to give the smoothest ride ?

I only adjusted it one click 'shorter/firmer' but the vibration has changed/improved.
Now it doesn't start until 55 MPH and is less noticeable.

I will adj it one click at a time and take test rides . . .  I'll let you guys know how it goes.

Kevin

PS:> I'm thinking this means the rear wheel is out of balance - the firmer suspension is just resisting it more. 
        I did order the Dyna Beads and will still put them in the tire.
        Once the beads are installed, I'll put the suspension back where it was and take a test ride - just to see if the Dyna Beads have an effect.


I tried to attach a photo but the uploads folder is full.  Here is a link to the photo in my flickr account.
http://www.flickr.com/photos/xriva18707/8124568703/#

[MotoRandy123]

I've tried mine at each setting and never had a vibration. It must be something below the
shock. The only thing rotating faster with higher speeds is the wheel.

 I took off my shocks yesterday (I was looking to improve their operation) and I did find the
 exhaust side shock didn't align to the mounting holes. It seemed to be 1/4" short! I ended up
adding a washer under the mounting eye (vertically) and loosing up everything to try to match
side to side. Maybe now mine will vibrate now that one side is not forcibly compressed by the
other side?

 The back shocks have horrible damping by the way. The springs should be stiffer and damping
should be softer but there is nothing you can do with the stockers...

[Zimmerman]

Just wanted to update the group - the vibration is still there.
It is a general vibration felt through the seat and floor - but not especially through the handle bars.

I adjusted the rear shocks hard, soft and in between - no effect - there is a noticeable vibration from 55MPG up to 60 MPH.
I've not driven the scoot over 60 MPH and it doesn't vibrate under 55 MPH.
It is enough of a vibration that I'm concerned about safety.

The front tire pressure was a little low - fixed that - same vibration.

Installed Dyan Beads - front and rear - same vibration.

Coasted down hill with engine off - only got up to 35 MPH - didn't hear/feel anything.
If I can find a big enough hill with a smooth road surface and little traffic - I may try coasting again @ 55+ MPH.
It's hard to hear with a full face helmet (if there is anything to be heard.)

The vibration seems to be MPH related rather than RPM related.
I say this because I run the engine at all RPMs as I accelerate - no there is no vibration until 55MPH.

- -

Any tips on how to isolate the cause (or eliminate possibilities) would be great.


How would a bad wheel bearing behave ?
Would it cause vibration at only higher speeds ?
How can I test for a bad bearing ?

What does drive belt slap feel like ?
It is speed related ?
How could I test for that ?

 . . . Kevin

[MotoRandy123]

I doubt a bearing would do that. The wheel does rotate faster as you speed up.
I think the top speed is 1750 RPM's at the wheel. A lumpy tire or out of round rim
might do it.

The belt slap is generally accelerating from a stop, you hear a rumble or thump
as the belt touches in the center between the 2 pulleys. All that happens at belt
speed so would go away as you max out the belt. It could happen when you let
 off the throttle suddenly.

 I guess a loose motor mount could cause vibration at high revs...?

[Zimmerman]

The problem is in the rear wheel / tire.

On the center stand at ~6500 RPM you can visibly see the wheel moving up and down.  Also gently placing finger tips on either side of the wheel (near the bead) you can feel the wheel wobble side to side.

I'm going to rig up some static jigs so I can slowly rotate it by hand - using te jigs to 'see' the problem.

Testing ideas welcome . . .

[MotoRandy123]

Well the manual says it's one of 3 things;
Bent Rim
Faulty Tire
Axle not tight

Your allowed 2 mm runout max. So if you can see it...

Try putting bike on center stand and wiggle rear wheel.
If it wiggles it's the bushing/bearing or loose axle bolt...

[Zimmerman]

Thanks Randy - I'll try that and let you guys know.

Also I'm going to rig up a static jig - I'll use it to closely inspect for bumps on the wheel or tire while slowly turning it by hand.

Forgot to mention, tests done in my last post were also done on our People 150. The P150 had no wobble.

[Zimmerman]

I grabbed the rear and tried to wiggle it - no movement - it seems solid.

Laying a ruler on the floor and spinning the rear tire by hand - eye balling the ruler and tire - I can see there is some side to side tire movement.

I'll have a dial indicator this weekend and will quantify that movement.


I've also noticed the rear disc break seems to rub a little and not consistently / evenly.  When I spin the tire by hand sometimes it continues the drift a bit, other times it stops drifting almost immediately.  It depends on where in the rotation the wheel (brake) is. This appears to be caused by the brake rubbing and not evenly.

I would think the brake shouldn't rub at all.

But the unevenness implies that the brake pads and disc are not 'square' to each other.

I will be checking that the axel / wheel is square.  (if it's not square that would also explain the brake.)


Feedback welcome

Question: When the scoot is 'assembled' by the dealer does the rear wheel get mounted, aligned or checked then . . . or is that done in the factory?

[MotoRandy123]

Very few brakes do not rub a bit, especially as they get older and stuck in place. Though
rubbing then skipping might say somethings crooked.

 I have 2 bikes in my cellar "shop" right now. The older BMW rubs for 1/4 or less of the
total rotation as the rear wheel is rotated. The Yager drags all the time (not sure if it's
the brake or the heavy mass of the clutch).

Some setups have "V" shaped clips that go over the top of the pads to hold them apart.

I would doubt the rubbing brake would create vibration only at high speeds but you could
remove the pads and ride it. Just don't grab the brake! Tie a bright ribbon around it to
remind you!

If the rear tire wobbles it's not clear from the manual what could be bad. It shows a long
 collar going into the wheel and some spline's on the shaft. And it's supported on the outside
by the swing arm. It looks that if the collar was short or axle nut loose it could wobble.

 I imagine one could bend the rim not sure what they are made of or how brittle the are...