How to fix High Speed Wobble or Pitch & Yaw

[ks80xs]

To all you tenured and experienced XS11G owners,

I have restored a 1980 model XS1100G that's been sitting dismantled in a tin shed for about 21 years according to the last registration on the license plate. This has a full touring ensemble, Yamaha fairing with the lowers, saddlebags, luggage rack with backrest, and finally a tour pack or luggage trunk.

I've ridden this bike locally around town on the interstate and from about 75 MPH and up this bike has a fairly consistent high speed wobble, not so severe, it's more like a pitch and yaw back and forth.

I've put a fork brace on the front forks, lowered the front and rear shocks which did reduce the severity of the wobble. I also put more air pressure in the front shocks which even reduced the wobble a bit more but it's still there.

I just recently took 500 mile trip (the 1st maiden long distance voyage since restored, with a passenger even) and the bike ran and performed marvelously, much better than I ever could have expected BUT...

The wobble was always there, it did not interfere with the performance or the enjoyment of the ride but I'd like to find the necessary modification that maybe (hopefully) some of you more tenured XSrs have found to remedy this situation.

I thought of putting bigger tires on it, changing the triple tree to a heavier unit, and even to point that the drive shaft and the rear drive gear could be the cause, don't know what to do about that.

I am at my wits end, I need help, can anyone of you folks help me out with this problem.

Thanks for any input you folks can offer,

KS80XS

[rdmcguy]

wobble wobble wobble

What you describe could be a lot of different things or a combination of things.You don't say whether or not the tires are new?how about the fork oil ?Steering head bearings?...sacked out rear shocks?..misaligned fork brace or forks tweaked...could even be improperly/balanced.. inflated tires...let us know what you find...

[TomB]

As said could be a lot of little things.

First check is over tight steering head bearings, they may feel Ok when riding slow but if too tight they will cause high speed yaw.

The next on restored bikes is painted triple trees, folks paint inside the holes that the stanchions clamp into, slide them out and scrape out the paint so the fork can be clamped firmer.

[James England]

I would suggest a methodical check from end to end......

1. Front wheel bearings
2. Steering head bearings
3. Wheel balancing on front wheel
4. Front tire for damage, bulging, lumps. Pressure
5. Swing arm bearings
6. Rear wheel bearings
7. Rear shocks for damage or play at bolt points
8. Rear tire for damage, lumps, flat spots. Pressure.
9. Spin each wheel, on the bike, next to a fixed pointer and see if the rims are out of true
10 check the alignment bead on both tires, both sides and make sure the line doesn't disappear into the rim somewhere

You may want to add checking the fork stanchions for straightness too. It's a bit more of a pain though...

[TADracer]

Start by checking the alignment of that big wing (I mean fairing) you have on front of your bike. Even a smaller windshield can make the lane wandering you describe happen at highway speeds so checking the fairing alignment might be a good place to start.

[ViperRon]

In mounting the fairing do not mount it without the rubber shims. Vibration needs a little flex and if there is nothing to absorb the vibration the fairing will eventually crack. The flex from rubber shims will not cause issues with driving if properly aligned.

[skids]

In mounting the fairing do not mount it without the rubber shims. Vibration needs a little flex and if there is nothing to absorb the vibration the fairing will eventually crack. The flex from rubber shims will not cause issues with driving if properly aligned.

Very true! In fact, don't try to "draw down" a corner by tightening a bolt if there is a gap. Find more rubber shims instead!

[BA80]

It's going to be in the front fork alignment or the steering head bearings. Mine had it bad until I replaced and adjusted the steering bearings.

[ks80xs]

pitch and yaw-wobble

What you describe could be a lot of different things or a combination of things.You don't say whether or not the tires are new?how about the fork oil ?Steering head bearings?...sacked out rear shocks?..misaligned fork brace or forks tweaked...could even be improperly/balanced.. inflated tires...let us know what you find...

Tires are brand new Avon Distanzia Duel Sport tires with tubes and balanced upon installation, Lowered front forks/with fresh oil during restoration (had the pitch and yaw even before that), no tweaked forks or misaligned fork brace.

Have not verified steering head bearings but there is no play in the steering that can be identified.

[BA80]

Have not verified steering head bearings but there is no play in the steering that can be identified.

If you haven't at least checked, cleaned and repacked those bearings you just found the problem. The slightest catch in them will throw the balance off. The races and rollers will get rust pits and will be catching ever so slightly particularly if the bike has been sitting a while.

[ks80xs]

pitch & yaw-wobble

As said could be a lot of little things.

First check is over tight steering head bearings, they may feel Ok when riding slow but if too tight they will cause high speed yaw.

The next on restored bikes is painted triple trees, folks paint inside the holes that the stanchions clamp into, slide them out and scrape out the paint so the fork can be clamped firmer.

Still need to verify check to see if steering head bearings are over tightened but the there is no paint in station clamp holes it is still original.

[ks80xs]

pitch & yaw-wobble

In mounting the fairing do not mount it without the rubber shims. Vibration needs a little flex and if there is nothing to absorb the vibration the fairing will eventually crack. The flex from rubber shims will not cause issues with driving if properly aligned.

Nice Bike Viper, looks quite a bit like mine but black, my fairing mounting bracket has never been removed from the bike, though the fairing has several times during restoration. With that said, the shims have been reinstalled each time the fairing was reinstalled but from what I can tell there is absolutely no play in the mounting screw holes to even get the fairing mounted incorrectly?

So you do not have any type pitch and yaw problem with yours whatsoever?

[rdmcguy]

nasty old grease

nasty 40 yr. old grease in the steering head.probably gummy at a minimum..or dented &damaged replace the races too..

[ks80xs]

pitch & yaw-wobble

If you haven't at least checked, cleaned and repacked those bearings you just found the problem. The slightest catch in them will throw the balance off. The races and rollers will get rust pits and will be catching ever so slightly particularly if the bike has been sitting a while.

You sound like you have good experience with this situation but I would like to ask you this, did your wobble seem more like a wee-wah back and forth? I ride the highway and watch my fixed fairing stay steady going down the road but I can see my steering moving back and forth against the background of the fairing, it almost feels like it's coming from the rear for some reason??!

[ks80xs]

pitch & yaw-wobble

OK guys I think I've got my first targets in this order
Steering Head Bearings & Races
Front and Back wheel bearings

Let me make a run at those and see if that corrects my problem, I will keep you all posted

Thanks a lot guys