Topic: "floating" at speed?

[asom]

I've noticed here lately that when I'm on the interstate and get up to around 65mph or higher I start feeling a floating sensation.  It's not hard and abrupt like catching the draft from a semitruck.  It's very much like my mothers lincoln towncar feels like.  kinda of like a pontoon boat on water.  also rocks side to side when this is happening.  Is this just the feel of a motorcycle on the highway or should I be thinking about suspension?

[asom]

it also feels kinda like a bicycle with a flat tire.  could it be tire pressure?

[gmonkey]

It's not always in the same places on the interstate, is it?

[asom]

I can't say for certain regarding wind pressure.  It definately is not the same spot.  I haven't tried hugging the tank when it happens because I'm chicken to change my center of gravity when it's happening.  I haven't ridden any other bike ever and I've only had this one for 3 months.  I've felt wind gusts and drafts from large vehicles and this is different.

It doesn't do this on open highways and I think it could be the way interstates are blasted into the countryside making a wind tunnel.

Are there mechanical problems with the same symptoms?

[mystic_1]

Could be a loose suspension, check you swingarm pivot, steering bearings, etc. 

mystic_1

[diskman]

Put it on the centerstand (if equipped) and see if you can move the rear tire left and right.  Look for play in the swingarm or bearings.  Severe spoke damage will make a wheel loose too.

My '80 650 need swingarm bushings and feels wierd with two people on it.

[Alan F.]

it also feels kinda like a bicycle with a flat tire.  could it be tire pressure?

Try a changing your pressure a pound at a time, 3 or so pounds plus or minus shouldn't hurt much, maybe you'll find the sweet spot.

Maybe ask in the CB750F thread too?

[camelman]

My guess is that you are experiencing weave.  Weave is a slow side to side resonance that is caused by the same issues that cause steering shake.  Check your head bearings to see if they are loose or if there are any rough spots, check your wheel bearings to see if they are smooth and tight, check your swingarm to make sure it is tight, it might be time to change fork fluid, and definitely check tire pressure.  Make sure your rear shocks are set to the same preload, that they actually operate correctly, and that they are mounted securely too.

Everyone has their opinion on where tire pressure should be, so do some online research.  Somewhere around 30psi rear and 28psi front should be okay.  You should also spin your tires with the bike on the center stand to see if they have any wobble, flat spots, high spots, etc.  I found that the guys who mounted my front tire let the inner tube slip between the tire and the rim, which caused a huge bulge in the side of the tire.

Camelman

[fastbroshi]

  Maybe it's a combination of the weave and just plain worn out shocks.  Some of the stockers reportedly went South after 5000 miles.  How much do you weigh?  I've got a 550 and I weigh about 210 with all my gear on.  My bike doesn't weave but I've got the wallows going on and I'm using the stock shocks.   Rebuilt forks with standard springs too, for that matter. 

  Couldn't hurt to match the springs in front and shocks setup for my weight.  Maybe so in your case too.

[IndyFour]

Is the section of Interstate that you commonly ride on concrete paved?  If so, is it a grooved surface?  Much of the Interstate loop around the city here in Indy (I-465) is grooved concrete and it sometimes gives that sensation when I am riding fairly fast.  Just a thought.

[Derby City]

+1 on grooves in the concrete. 

[mystic_1]

+1 on grooves in the concrete. 

Steel grating on bridges does the same thing.

It's important not to fight it, just relax and steer the bike straight ahead.  It's not as unstable as it feels.

mystic_1

[asom]

it is newer concrete and I do believe it is grooved.  I haven't checked any of the systems mentioned.  Hopefully, I good once over and a little more confidence and experience will take care of it.

[seaweb11]

Try to find a nice stretch of clean road, non grooved before you tear her down.  Your problem sounds like a couple of places in Washington I have been on
1st time it can be a bit unnerving.

[Popwood]

For all the guys who have thousands of miles under their belts their suggestions are right on, as usual. But as a somewhat newer rider, active for just 2 years now, I can remember a similar sensation at higher highway speeds when cornering or taking a curve. I felt the bike was in control and not me.

With more experience now, I have control and I think it's all about "the line." You set a line, or arc or radius, on a curve, and the bike holds "the line" as you control the bike. If you don't control the bike, it finds it's own "line" and can "float" you right into another traffic lane. I found it a scary and very uncomfortable feeling, needless to say.

I suggest some practice, a conscious effort to hold "a line" on a curve to get the feel of it. Putting the front wheel in position, body position, a bit of lean, it's all a dance.

All this said, if it happens on a straight run of highway, well, never mind and regardless, check your suspension points.

[scottly]

Grooved roads are a Government plot to kill motorcyclists!! Well, that's how I felt the first time I rode on one.

asom, do all the checks recommended, as well as check your wheel alignment, just to be safe. Also, if it is the grooved surface, slow down; that will reduce the ugly feeling.

Congrats on the first 1000 miles!!!

[333]

I agree with the swingarm joint/ steering head bearing crowd.  But also you should check the rear wheel alignment and both wheel bearings.  Regarding tire pressure, put in what the bike says, not what the tire says.  The tire manuf. doesn't know what your bike weighs.

[Raef]

popwood +1

I notice a lot of new riders being ridged sitting straight up and steering the bike, this is a good way for the bike to go one way and you the other. you have to relax a little and use your weight there is a thread on this site about that very topic. I wish I could tell you the title.

Mark

[Spanner 1]

Lay off the Ambien, daytime 

[333]

You may be referring to counter steering.  But another thought just came to me.  This also could happen as a result of going up 2 or more sizes of tire on stock rims.  At highway speeds, the contact patch is so small, there is little to grip with.

[asom]

I'm heading over to Nikkisix's to finish working on the dent and primer on the tank.  We'll give a once over and then I'll hit that same stretch on the way.  I'll relax, pick a line, slow my roll a bit and see what happens.  I'll report back this afternoon.

thanks again folks!

[Duke McDukiedook]

Longitudinal grooves are the problem, they always put me on edge, especially when crews overgrind them to get their profilograph bonuses.
Pucker factor increases mucho. 

Transerve grooves are much better but they are louder on bikes and cars.
 

[asom]

nothing wrong with the bike.  it appears to have a been a e.s.o. problem...equipment smoother then operator.   road, wind, rider... pucker factor was too high.