High Speed Weave after intalling windshield

[GS1100GLMLA]

On my 1982 GS1100GL I had the high speed weave at about 90mph. I replaced the fork seals and it dissapeared. I just purchased a National Cycle Plexifairing 3 and installed it. I really love if but now I have the high speed weave again. Except it is a little worse than it was before. Is that typical after installing a large windshield? Anything I can do to eliminate the high speed weave with the large windshield?

[tconroy]

I have a large windshield and have no problem at all.You might want to check your steering bearings for play.Or maybe tighten it up a little.Also check your swingarm bearings for play. Putting a new windsheild on will only increase a problem that already exists.If you can feel it in the handlebars I would say check out the steering head bearings for sure.If left alone It can lead to a high speed wheel wobble that could be fatal.

[Mysuzyq]

I run the smaller NC 'Deflector' on my E.....one thing I found is that the screen has to be perfectly centered on the bike to provide proper handling at higher speeds...even being off by a half inch will cause noticable drift....your shield in not a 'quick-detach' one I believe, so it might be easier to secure once centered, but the Deflector needs a tweak almost every few rides to correct...also riding into a slight cross wind, while no problem at legal speeds, will provide some hairy handling at higher speeds . Raking the screen back as much as possible, while still getting decent protection also seems to help.

Tony.

[Boondocks]

A windshield can cause instability if it reinforces a resonant frequency. I have a National Cycle Plexifairing 2 that I use in the colder months with no stability problems. I have had high speed weave problems in the past, but no more.

See my posts starting at High Speed Weave for the cause and some tips for troubleshooting and fixing the condition.

[KGB]

Sounds silly......but check tire pressures.

And as others said, angle the shield more.

[GS1100GLMLA]

Thanks for all the comments. I read as much info I could find on fixing this problem and realize that it is a problem with the rear of the motorcycle. I read the long Doctoral thesis on motorcycle weave/wobble that a memeber hear recommended and tried to adjust the settings base on what it said. I have the original shocks on the rear with the settings on #4 for stiffness and #3 for dampening. I have the original springs in the front and just replaced the seals and oil in the forks with 15W and set the levels exactly and put 8 pounds of air in each. I also lowered the motorcyce on the front forks by about 3/4". I weigh about 170 pounds. I also put new original size Chen Shin tires on the front and rear. Both are set at two rider high speed riding pressures(32# front & 30# rear).How do you check/determine if swing arm bearings are bad. Also, how do you check or determine if the rear wheel has excessive runout?

[Boondocks]

Thanks for all the comments. I read as much info I could find on fixing this problem and realize that it is a problem with the rear of the motorcycle. I read the long Doctoral thesis on motorcycle weave/wobble that a memeber hear recommended and tried to adjust the settings base on what it said. I have the original shocks on the rear with the settings on #4 for stiffness and #3 for dampening. I have the original springs in the front and just replaced the seals and oil in the forks with 15W and set the levels exactly and put 8 pounds of air in each. I also lowered the motorcyce on the front forks by about 3/4". I weigh about 170 pounds. I also put new original size Chen Shin tires on the front and rear. Both are set at two rider high speed riding pressures(32# front & 30# rear).How do you check/determine if swing arm bearings are bad. Also, how do you check or determine if the rear wheel has excessive runout?

Your original shocks are long since shot if you have over 5,000 miles on the bike! They should be replaced. In the meantime, I would try setting them at the softest settings for preload and damping and see what effect that has on the weave. You can experiment and adjust them from there.

The recommended rear tire pressure on my bike (and probably yours too) is 40 psi for 2-up high speed riding, not 30 psi. I would start with 25/28 psi front/rear, the lowest recommended setting for a single rider and see the effect on high speed weave. High speed weave is usually not a problem when riding 2-up, because the extra mass damps the resonance causing the weave.

To check the swing arm bearings without disassembly, you could put the bike on the center stand and try to move the rear tire from side to side. If the swing arm is loose, you may notice some play.

I spotted excessive rear tire runout on mine by putting the bike on the center stand and running the tire at slow speed. You can see it if the tire isn't running true. A dial indicator can be used to check the rim for axial and radial runout. The limit is 2.0 mm.

Although you have new tires, sometimes tires themselves are the source of the excessive resonance. New tires are generally an improvement to damping of resonance, but results vary with different tires. It's important to balance the tires, especially when handling problems are evident.

Try moving your weight a little forward toward the tank, or crouching over the tank. Also trying putting your weight on the footpegs. This lowers the center of gravity and might help damp the weave.

[GS1100GLMLA]

Boondocks, Thanks for the excellent advice. I set my bike up exaclty like you said and had no problems at all from the high speed weave. I tried it out a couple of times and the second time into a 15-20 mph wind. Going into the wind with that large windshield would only get me about 107 mph according to my speedometer. I will purchase some new rear shocks and eventually do the swingarm bearings and steering bearings this spring. Thanks guys.

[Boondocks]

You're very welcome.

I'm glad it worked for you.