Excessive vibration and pulsing at high rpm/speeds

[llaen]

Hi folks,

I'm attempting to diagnose a problem but need some pointers where to look.

The last couple of times I've spent 30+ minutes on the highway, I noticed that my right hand gets numb from all the vibration. I've had a mild case of numb throttle hand before, but never so consistently.
Today I also noticed a definite pulsing going on at high speed. I put my hand on the left side of the tank while holding the throttle steady and noticed a pulsing at around 2 second intervals.

I don't think I'm just being paranoid here! Something's up.

There have been no effects on handling or performance.

At this point I feel like it could be anything - from wheels to brake rotors to anything in the engine. Any pointers on things I should look at first and eliminate from that list?

Thanks a bunch!
Would hate to lose the bike for an extended period of time in the middle of the season (with a giant bill to boot).

[mister]

Engine pulsing is normal at certain rpms. So please be more accurate with your description of "high speed". What speed, what gear, what sprocket set up do you have, what rpms?

Numbness isn't necessarily from vibration even when people Think it is. Possible causes include...

- too tight a grip on the grip
- gloves too tight and become tighter when hand clenched around grip
- incorrect wrist angle slightly restricting blood flow
- vibration
- wrong gloves for very cold weather

Try this... when you start to feel your hand go numb, relax your grip and only hold with your pinky and ring finger. After a short while hold with index finger and thumb only. Alternate. This usually relieves numbness due to unconscious tight gripping and once gone will usually not come back. If it does, repeat.

Michael

[llaen]

Hey Michael,

Thanks for the input!
High speen/rpm was about 74 mph and 7krpm in 5th gear, stock sprocket.

That said, you may be right. In hindsight I was very tired on those last 2 rides, so it's completely possible that, as a side effect, I was subconsciously gripping the throttle a bit too tight. Then instead of going to sleep, I posted here .

I'm gonna check the various bolts just in case, but it's probably nothing!

[jestercinti]

Did you change your bar ends weights?  In addition to what Mister said, this causes vibration in the handlebars too.

Try heavier bar ends if it persists.

[gsJack]

The GS has buzzy bars from engine vibes.  They are damped out quite effectively by the bar end weights.  If the bar ends are tightened up too much the bars will get very buzzy, the bar end weights must be loose enough to vibrate independent of the bars but not loose enough to fall out.  Simply grab them and turn by hand to loosen or tighten them.

The first summer I had a GS about 13 years ago my hands both got very numb after an hour or so, all the fingers would slowly get numb and I lost all feeling but I could still ride and operate the clutch and throttle without even feeling them.  I was not a new rider having put about 230k miles on 4 old Hondas before the GSs but the seating position was different.  The old standard Hondas had a very errect riding position and I leaned forward with my weight on the bars on the GS.  A set of GenMar risers moving the bars up and back all but eliminated the problem at that time. I was also about 67 yo when I got the first GS.

Occasionly now approaching 80 yo I get numb hands on a long twisty downhill with my weight on the bars and gripping a bit more tightly but I can relax and shake it off and keep on going.  The GS engine is a bit buzzy but it can be controlled.  Most of my 170k GS500 miles have been buzz free.

[comradeiggy]

I've found that my throttle hand going numb is actually due to my gloves, and has nothing to do with the vibrations you can feel through the bars.

[89500inPA]

If you have not done so recently, you may also try synching your carbs. I find that after I do this, vibration can be cut down significantly, particularly at higher revs.

[llaen]

Thanks for all the good points/suggestions! Definitely gave me a peace of mind.

I haven't touched the bar ends.
Syncing the carbs may be a good idea as I haven't done it and who knows if the previous owner(s) has at any point.

[mister]

I've found that my throttle hand going numb is actually due to my gloves, and has nothing to do with the vibrations you can feel through the bars.

Try larger gloves. The gloves should feel good clenched. Not good open and then tightening and blood-flow-restricting when clenched.

Michael