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I just put a new Dunlop on the front end of me ’85 1200a. I had the tire mounted and balanced at the local shop, but put the wheel back on myself. Everything seems fine, except for a bounce. It is almost like a small hoop in the front end between 30 and 45mph. Over that it smooths out. I tried double checking the balancing, seems fine. The tire doesn’t seem to be out of round, not that I can really tell.

What have I done wrong? Everything was completely smooth on the old bald tire....

(first post and i'm already asking for help)
 

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Hi thorak

I fitted 2 avons to my 1500 18 months back, within 400 miles the rear was oval, the front followed 200 miles later, thankfully my dealer, could see the problem and tyres were changed.

get some one to spin the wheel while you check the mid point using a piece of wood, there should beno noticeable out of round.



welsh winger
 

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thorak, I'm wondering if possibly you may have not fully seated the bead on the tire. Sometimes they can look just fine until you inspect closely and you'll see, close to the rim's edge, where the tire's moulded line on the sidewallis not evenly spacedaround the circumference of the wheel. Sometimes it can take up to 70 psi or more to seat the tire's bead, especially if the tire was installed dry.

Vic
 

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thorak wrote:
I just put a new Dunlop on the front end of me ’85 1200a. I had the tire mounted and balanced at the local shop, but put the wheel back on myself. Everything seems fine, except for a bounce. It is almost like a small hoop in the front end between 30 and 45mph. Over that it smooths out. I tried double checking the balancing, seems fine. The tire doesn’t seem to be out of round, not that I can really tell.

What have I done wrong? Everything was completely smooth on the old bald tire....
thorak, a wheel disturbance 30 & 40 MPH isn't usually a tire balance problem as a balance issue comes in at a higher speed & doesn't usually go away as you go faster.

On an automobile wheel/tire a disturbance at 30-40 MPH is usually a 1st order vector problem (basically an out or round tire or improper built tire that internally distorts as it rotates).

Start by checking the air pressure, too much air pressure could cause a low speed bounce. Then see if there is a match mount mark (like a dot of paint) on the new tire, if found the tire shouldhave been mounted so that mark is at the rim valve stem.

If you can't find anything obvious I would call Dunlop & talk to one of their tire engineers, my guess is you aren't the only one that has experienced this problem.

Twisty
 

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If it's not the balance then I'd say the tire pressure is set too high. Don't ever go by the tire pressure stamped on the sidewall of the tire as a guide. Proper tire pressure is listed in your manual.
 

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Gotta vote with Twisty on this one, most likely an out of round tire. Not all that uncommon. Nasty speed to have the problem since that's also close to the natural resonance of the Goldwing fork wobblies.
 

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Look for the "light spot" painted on the tire.. It must be located at the valve stem. If it is, then the tire is just out of balance and should be re-balanced. If the light spot is not at the valve stem, it must be re-positioned and re-balanced..

Only other problem is a tire that has a mis-mached belt which could cause that hoop affect you are getting and all the balance jobs in the world won't cure it... Just get a new tire..
 

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Thorak, just a thought, those should be a directional tire, make sure the guy didn't get the "Direction" reversed when he installed it!

plus there should be a little dot that should go by the valve stem when mounted?:baffled:

By the way most bike tires will self balence with the exception of a couple of brands, but my Dunlops ride better without weights! Sounds crazy, I know!
 

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WOW… I didn’t expect so many replys…

The dot is lined up with the valve stem.
I double-check the air pressure.
I have tried similar to the block of wood idea, but didn’t see any move in the tire.


I didn’t install the tire myself, just the wheel. I don’t know how the shop balanced it. It does have two large weights near the valve, so they did at least try to balance it.

Anything else I should try before I take the wheel off to have it balanced again… :(
 

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They don't always get the balance right at shops. Try removing the weights one at a time to see if it gets better or worse. You can always replace them if it doesn't help.
 

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Thorac, jack your bike up and spin your tire , if it is "Balanced" it should stop in diffreent places each time, if it comes to a stop every time with the weights at the bottom then it's a balence problem!

But, big but, usually a balance problem occurs at high speeds and gets worse with speed?!

I don't know a 10th as much as most of these othere guys, just going off experience!

Did you check the direction of the tire to make sure it wasn't put on backwards ? It's easy to do ?
 

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thorak, if you attempt to check the balance of your front tire while it is still on your bike you will need to retract the brake pistons so that the brake pads will not be causing a drag on the rotors, then the wheel can can spin as free as the bearings will allow it to. If the tire is in balance it will stay wherever you place it, but, if out of balance it will fall to the heavy side every time and will need a weight to offset the heavy side.

Another thing to inspect is the runout on the rotors. If someone has dropped your wheels and bent one or both of the rotors you could end up with the problem you state. Roghly check the runout on the rotors by placing a piece of wood on a block at the same heightas the rotor and spin the wheel to see if the side of therotor contacts the piece of wood consistently in all its travel. If there is contact, then no contact you will know the rotor is bent. Typically this is checked with a dial indicator and is measured in thousandths of an inch so you will have to check carefully.

Vic
 

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GoldWinger1984, you make some very good points!!

I always undo the calipers and hang them with bungie cords to spin the wheel!

And you're right about the "Rotors", hard to see with the eye if they are warped?!:clapper:
 

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I have spun the wheel with the calipers off. The wheel seems to stop randomly.
The directionally arrow is pointing the correct direction.

I will have to take some time to check the rotors tomorrow (already late here).

I just put new pads on, and thought about replacing the rotor as well. I couldn't find anywhere that had the vented style currently on the bike. Presuming this is the issue, where can I find disks ?
 

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You might not need rotors yet, first see if you have a tire problem?
 

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I'm not going out to buy anything yet. I just want to know how much money i'm going to be spending if that is the problem.
 

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thorak wrote:
WOW… I didn’t expect so many replys…

The dot is lined up with the valve stem.
I double-check the air pressure.
I have tried similar to the block of wood idea, but didn’t see any move in the tire.


I didn’t install the tire myself, just the wheel. I don’t know how the shop balanced it. It does have two large weights near the valve, so they did at least try to balance it.

Anything else I should try before I take the wheel off to have it balanced again… :(
thorak, wheel imbalance is proportional to the rotating speed of the tire so if you have a wheel balance problem that you could feel at 30 MPH it would be so bad at 60 MPH you could hardly ride the motorcycle. Since your problem goes away at faster speeds I doubt you have a wheel imbalance problem.

You might look at your anti-dive settings as you might have inadvertently moved one of those. It's also possible you could have a plugged anti-dive valve if you fully extended the front forks while installing the front tire. Dirt tends to settle in those anti-dive valves & if plugged could cause a harsh ride type front end shake at lower speeds (would feel like way too much air in the front forks).

If nothing else found you might have a bad tire (it happens)..

Twisty
 
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