Oscillating bars and tankslappers

[RitchieD]

Hey guys n gals,
I'm getting some really good bar wobblers at the moment whenver I come off the throttle.

IIRC, my old TRX would do this when the front tyre was worn.
this ones' frnt tryre appears to have plenty mileage left.

If I'm slowing down and lightly hold the bars, they start to oscillate, then between 50mph and 40mph, its getting on for a slapper.
I was told to check wheel bearings, disks, and head bearings, but cannot 'feel' anything amiss.

was out for a hundred or so miles this last weekend, and frankly, it's spoiling the ride.
If I brake the problem goes away. If I brake with the rear brake only, the thing damn near goes nuts.

Anybody got any ideas?
PS I'm skint, so the fix needs be cheap.........

Thanks,
Ritchie

[philk]

Check wheel is straight,
Ensure tyre is in balance.
Check swing arm for movement, and rear tyre and bearings and wheel are ok

[gregs656]

If I do the 'cool' let go of the bars thing which I like to do every now and then - my bike sometimes gets a bit of a freak on. I've always assumed it was down to the vibes from the engine.

[trixynut]

Mine did this.

If I was 'coasting' to a stop in say 3rd gear with no throttle or brake, and let go of the bars, when it got to about 40mph it would start to slap like a ....er, slappy thing!

I used to do it just for fun sometimes!

I took the wheel out, checked the wheel bearings, checked the head bearings, greased it all and put it back together with everything to the correct tightness and with a new tyre on, and to the correct pressure and balanced (when the tyre was done) and it went away!

So, must have been one of these things, but I don't know which.

[gregs656]

wheel balance would be my guess out of all of them

[idl1975]

It's not normal, that's for sure (remember trixynut has a USB front end conversion). It's not likely to be tyres, unless you have the strangest tyre combination ever. I've had all sorts of wacky combinations and worn out rubber, plus mine is 10mm down at the front and 10mm up at the back, and it has always run die-straight on a shut throttle.

I would think most likely culprit of those mentioned is head bearings or wheel balance (balance weights fallen off?). IMO, if you had wheel bearings bad enough to cause this, you would most probably notice. Seems unlikely to be a bent wheel - you would see it, and you'd probably have to run over a passing highland coo to damage one that badly. Have you (a) checked that both axle nuts are secure and (b) that the rear wheel is at least vaguely in the correct alignment, i.e. by looking at the chain adjuster block markings? Sorry if these things are too obvious.

Hey guys n gals,
I'm getting some really good bar wobblers at the moment whenver I come off the throttle.

IIRC, my old TRX would do this when the front tyre was worn.
this ones' frnt tryre appears to have plenty mileage left.

If I'm slowing down and lightly hold the bars, they start to oscillate, then between 50mph and 40mph, its getting on for a slapper.
I was told to check wheel bearings, disks, and head bearings, but cannot 'feel' anything amiss.

was out for a hundred or so miles this last weekend, and frankly, it's spoiling the ride.
If I brake the problem goes away. If I brake with the rear brake only, the thing damn near goes nuts.

Anybody got any ideas?
PS I'm skint, so the fix needs be cheap.........

Thanks,
Ritchie

[ekoja]

I have experienced this and it is always cured by replacing the front tyre.

[cobbadiggabuddyblooo]

Had a similar problem and hit a small pothole turning at a set of lights the other week and destroyed a front wheel bearing,so replaced them both and found no problem so far,had bearings checked on last frontend rebuild(at $6.00 each aust. better to just replace them) from being merged on just after taking off from a set of lights.(just got it back from frame straightner 3wks earlier after havin a car do a u turn infront of me)
After fighting against the front right guard I bailed out and aquaplaned on my back at 50km/ph but the bike kept goin for another 200m till it got to the next set of lights and the only thing to stop it continueing along stanley st,down the hill past the Gabba cricket grounds was running up the arse of a maxi taxi. Cab driver couldnt believe it as I'm walkin down the road back in the distance headin towards the bike. The car driver was fined after goin to court but the judge didn't believe my explaination on short shifting in wet weather , being in 3rd gear and beautiful engineered motorcycle. She thought speed was a factor but couldnt prove the fact which it wasn't.
So at bucks for a wheel bearings its well worth just replacing them
Hank(rather die a living spirit than live a dead one)

[slow codger]

Yep had this as well.
Check tyre pressures and have a play, as you will notice that those who have taken tyres off etc found its gone away when the wheel is put back together and the tyre put on, meaning they have blown the tyre up to the pressure they like.
Go about 3 psi above recommended and see if this works.
Also when letting go of bars do you sit up? If so the riding position is altered and the weight is put back on the rear end, as is putting the back brake on. try altering the bar/riding position to see if this helps. I have rear sets so weight is front end biased anyway, letting go of the bars I still have to grip the tank with my thighs to stop myself sliding forward.

Dave E

[RitchieD]

Thanks for all the replies.
It does appear to happen regardless of where I sit; up against the tank on my stomach or leaning back.
Didn't happen with the wife on the back though

When I had a peek over the fairing, it did look like the wheel or tyre wasn't straight and true though.
There might even be marks on the wheel where a weight might have been.

I'll get my local tyre man to check the balance etc.

Thanks again
Ritchie

[bernardo]

funny enough I've got exactly the same problem, started about 100 miles after i fitted a new tyre

[brockzila]

I got the same problem. i found it got better when i set my tyre pressures, but now my tyres are shot and its not going away. am putting new tyres on next week and will let you know the results.

[idl1975]

funny enough I've got exactly the same problem, started about 100 miles after i fitted a new tyre

Hmm, I have always used Metzeler or Pirelli front tyres and have never had this problem with any level of wear.

[bernardo]

Brand new pair of Pirellis on it, (70 section front, massive improvement on the 60 section). Just realised something, problem only started when I dropped the front tyre pressure to standard, shop looked to have overinflated it, maybe thats it.