help, strange vibration

[racerxnico]

Hello,
I'm a big fan of the GS series and have owned a 550, an 850 and my current bike is an 83' GS1100E. She has been a fine bike and I have put about 26k miles on her in the last two years including an 1163 Ironbutt day.

Last weekend I was getting onto the freeway and I was accelerating very hard. When I backed off the throttle she didn't feel right (sort of buzzy with more vibration than normal). It was a short trip and I didn't think too much of it, especially when it was back to normal the next day.

It's been fine for the week so far until last night. I had to make a longer trip (to Edmonds from Seattle) and it ran fine on the way up. On the way back the buzzing and vibration were back. I stopped to look for anything obvious, but I am stumped. It was doing it again this morning on my commute into work.

I don't feel the vibration in the handlebars. It is all in the seat and the gas tank (where the knees touch it). I balanced my own tires, but that was 5000 miles ago (pre iron butt) and the weights are still in place and it feels like a finer vibration than that anyway. All bolts, engine mounts etc, that I inspected last night are fine. I can't really feel the vibration revving the bike when it is stopped.

Has anybody experienced something similar? Does anyone have ideas of what I should look into? Any help or advise appreciated.

thanks

[lhanscom]

You may want to sync your carbs, that can cause a vibration.

[Hoomgar]

Like Luke said that is usually the #1 cause. Most of the things after that are much worse. It could be a twisted crank. That is exactly where you would feel it.

[racerxnico]

I'll try to sync the carbs this weekend then and pray that that's it. I appreciate the input

[Anonymous]

I thought that Suzuki had made the crank on the 83 stronger and that the twisted crank problem was more likely on 82 and older bikes.

[Anonymous]

Suzuki started welding the 4 valve 1100 cranks in mid 1982, they weld all the journals except the one at the primary gear, always wondered why the didn't weld all the journals. I doubt a twisted crankshaft, it's kind of unusual for the welded ones. Maybe just the carbs !!!! Good luck

[Hoomgar]

There you have it. I didn't know that guys. Thx.

[Anonymous]

Is your vibration above a certain speed?

Mine had vibration the last time I rode it a few weeks ago, but only above 75 mph.

I was told to check the valve clearance and to sync. the carbs.

I'm in the process of doing that now. I will report here when I'm done to let everyone know if that helped.

Also check the screws that old the cosmetic cam endcaps on. My vibrated a screw loose and the damn thing fell out! when they go back in, they're going with Loctite blue...

[racerxnico]

it is more noticeable at speed, but it seems to be happening accross the board. I just ran out to grab lunch and noticed that if I am idling along at say 30mph and I give it a little gas that I feel the vibration kick in. I also noticed that I can feel it when engine braking. I'm feeling more encouraged that it is the carbs, but we will see.

[Anonymous]

If it's related to engine speed, it is almost certainly one of the three:

1. Carbs out of sync.
2. Valve clearances out of spec.
3. Carbs diry or misadjusted.

Check them in reverse order of how I listed them to save possible expense.

Read up in your Clymer manual, and you'll see it's not too bad.

[Carter Turk]

Loose clutch hub nut if not the carbs, maybe.

If the carbs get synched and the vibration is still there. Might be worth a check. Get the APE or Falicon nut if it is loose.