New Front Tire Causing Vibrations?

F

Flywheel

Well-known member
Here's the skinny: I've got a problem with new Pilot Sport SC tires on a Burgman 650. The original tire/wheel setup wasn't balanced (Bridgestone TH01, which are OEM replacements). No noticeable handling issues at all speeds.

Removed the rear tire/valve first. Mounted new rear tire/angled metal valve and went for a ride. No obvious problems. Did the same for the front afterwards. Up to highway speeds everything seems fine. On the highway, unusual vibration starts to intrude through the bars. Subtle at first, worrisome as the speed climbs. Nothing close to tankslapper, but I'm sure it's NOT supposed to be there.

Since the wheels weren't balanced (as they weren't previously), I balanced front and rear. Same results. Quadruple-checked all the fasteners and the tire carcass. Nothing damaged, loose or overtightened. Wheel bearings seem fine (spin freely, no wobble, grinding, debris). I need to physically check the steering head, but the forks/triple don't exhibit signs of damage or looseness (front end jacked off ground).

Accelerating, braking and steering don't seem affected until the vibrations begin. After that, who knows, since I naturally back off. It's definitely NOT engine vibration or road irregularities.

Some have suggested the Michelin's profile could be responsible. The OEM Bridgestones are supposedly specifically designed for the Burg and the Michelin's are more generic maxi-scooter tires. Any ideas before I take it to the local shop? Thanks!
 
check it for cupping? is the profile smooth ? defective tire i smy guess i cant see the profile causing vibration. I would re balance the tire too , maybe a weight fell off?
Flywheel said:
Here's the skinny: I've got a problem with new Pilot Sport SC tires on a Burgman 650. The original tire/wheel setup wasn't balanced (Bridgestone TH01, which are OEM replacements). No noticeable handling issues at all speeds.

Removed the rear tire/valve first. Mounted new rear tire/angled metal valve and went for a ride. No obvious problems. Did the same for the front afterwards. Up to highway speeds everything seems fine. On the highway, unusual vibration starts to intrude through the bars. Subtle at first, worrisome as the speed climbs. Nothing close to tankslapper, but I'm sure it's NOT supposed to be there.

Since the wheels weren't balanced (as they weren't previously), I balanced front and rear. Same results. Quadruple-checked all the fasteners and the tire carcass. Nothing damaged, loose or overtightened. Wheel bearings seem fine (spin freely, no wobble, grinding, debris). I need to physically check the steering head, but the forks/triple don't exhibit signs of damage or looseness (front end jacked off ground).

Accelerating, braking and steering don't seem affected until the vibrations begin. After that, who knows, since I naturally back off. It's definitely NOT engine vibration or road irregularities.

Some have suggested the Michelin's profile could be responsible. The OEM Bridgestones are supposedly specifically designed for the Burg and the Michelin's are more generic maxi-scooter tires. Any ideas before I take it to the local shop? Thanks!
Click to expand...
 
I've never personally used angled valve stems, I prefer the low profile SS.Valve stems. I've known a good friend who got a angled valve stem installed in the US...only for it to fail after a bit. It could be that your valve stem is loose?

How did you balance your wheels - does the vibration occur at a certain speed range?
 
frekeyguy said:
I've never personally used angled valve stems, I prefer the low profile SS.Valve stems. I've known a good friend who got a angled valve stem installed in the US...only for it to fail after a bit. It could be that your valve stem is loose?

How did you balance your wheels - does the vibration occur at a certain speed range?
Click to expand...

I've run the solid angled for years on track bikes with never a problem
 
gcrouse--The tire has maybe 20 km on it, so no abnormal wear has appeared. The tire itself a smooth tread with sipes, similar to most streetbike tires (no knobs like an mx or dualsport).

No weights fell off. I'm using plastic airsoft BBs as Dynabeads (waits for eye rolling to finish). I've used both conventional balancing and the BBs on my previous bike (zx6e) and never noticed a thing over a range of speeds, temperatures and road types (split 50/50 over 14 000ish km). The Burgman was sold to me with neither weights or beads and the sidewall code dated to 2004! No real issues with that setup, although the wear bars were showing.

frekeyguy--The stems are metal (steel?) with rubber seals and a 45 degree bend. They are firmly tightened and the air pressure was checked before each ride. No detectable leaking, 33/36 psi as recommended by the owners manual. No suggested pressure on tire sidewalls or on Michelin's online catalog. The vibration begins faintly at 12 km/h and becomes progressively worse up to 13 km/h. Didn't push it further than that, although as I mentioned, it never reached the severity of a tankslapper. Just very unnerving.
 
It seems that "dynamic" balancing isn't always dynamic enough. I took the Burg to Parker Bros and they quickly removed the BBs and rebalanced the front wheel with everybody's favourite chewable--lead! The vibes are gone. Still no sign of loose or damaged anything, so the problem is resolved.
 
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