Handlebars Vibrating

At about 3000 rpm, the handlebars on my 1995 Kawasaki Vulcan 1500A will
start to vibrate for 1-2 seconds, then stop for 10-12 seconds, then begin
vibrating/shaking again.
If I hold the bars firmly with both hands, it's less noticeable. If I just
rest
my hands on the bars, they will vibrate more. When I go faster/increase
rpms, the vibrations start and stop sooner, and feel stronger.

I plan to do the following:

1. Have the front tire I put on the wheel myself, spin tested by the
dealer.
2. Check the steering head for wear.
3. Replace the fork oil (since I'll have the front end apart .
4. Probably go ahead and replace the front wheel bearing (2nd set of KAW
bearing that have about 60k miles on them).

Please let me know if there are any other parts to check and/or replace that
might be causing the vibrations.

All tips, suggestions, and comments welcome.

Thanks,

Manjo 1995 KAW Vulcan 1500A9

 

It's easy to determine if the vibration is excited by engine or wheels
and final drive - just test in different gears.

Sounds like a long shot to me, but checking it is never wrong.

Even longer shot, but has other merits.

Use rubber sealed bearings even if that is not original fitment. Buy
bearings at motorcycle dealer if you really like the owner, you
can usually get better prices at a general bearing supplier. OTOH,
100 000 km on a set of bearings is not bad.

The engine ? Partly joking, partly not. Do check that the engine
mountings are tight and any rubber dampers are fresh.

Have you changed anything on the handlebars ? Longer mirrors,
heavier grips, cup holder, windscreen added and supported from
the bars ? Anything that changes the weight, length or stiffness
can change when and how much things vibrate.

 

Ron,

http://www.barsnake.com/products/barsnake.html

Pretty interesting and a well thought out product. This may be the last try
to eliminate the vibration. I hesitate to get one now, only because the
vibration is a new phenomenon, and has to do with something that has
changed, like my installing the tire, myself.

Thanks,

Manjo

 

OH- Excellent idea. Will test this first chance (just got 2 feet of snow
here and I'm off the road for a long while).

OH- I put the front tire on myself backwards, and had to take it off and
remount correctly (arrow towards direction of travel, my dumb .

I replaced a set of 5.5" x 4.5" risers with a set of 4" x 2" more
substantial risers.

I'm using the same w/s and w/s mount; same mirrors and grips; no cup holder.
Same bar mounted tach and speedometer.

I'll put the bike up on the lift and see if there's any play in the steering
head. I can then remove the wheel and take it to the dealer's shop for a
spin test.

Many thanks for the ideas and suggestions.

Manjo

 

Check the motor mounts and retorque bolts.

Do your changes one at a time so you know what effect each one has.
If you did them all at the same time and wound up with a new problem
you'd have a hard time sorting out which one caused it. (This assumes
you're doing the work yourself).

Start with the easy low cost stuff first.

Why would you have the front end apart and how would that make
changing fork oil easier ?

 

I'll be doing the work myself. I wish I had some warm weather and time to
do one thing at a time, and then road test the change. I'm sort of
snowed-in/frozen-in here in MA, for the next several weeks. I'm going to do
all the stuff needed to be done over the next couple of months. I can run
the engine in the garage, I just won't be able to safely do any road
testing for a while.

Last time I changed the fork oil, the drain plugs wouldn't budge. So I took
the forks off the bike, drained them, and then re-installed them for the
refill. I have some new bars to fit to the bike, so the old ones will be
disconnected, the front wheel will be off to be spin tested, and the
steering head will be apart to check the bearings, so most of the grunt work
will be done when I change the fork oil this time. Out of curiosity, I will
try applying some heat to the plugs this time, just to see if they loosen
up. They were probably secured with Locktite Red, which I hadn't considered
last time.

Thanks,

Manjo

 

[snip]

you might be better off just taking the forks off again. My VFR also has
drain plugs, and I used it on one leg, just to see what it was like, and
then did the other leg by dropping it and disassembling.

I felt that taking it apart (not all the way, just removing the cap,
spring and spacer) was no more trouble, and made measuring the fork oil
level much easier. Since it was 16k maintenance time, I also took the
opportunity to measure my springs and generally clean things out.

 

Only reason I suggested this is that shotgunning a problem can leave
you unbelievably confused when you do six things and then discover
something new is screwed up. I guess if you work your way through
methodically, you ought to be fine.

Do you ever see this problem standing still in neutral or have you got
to be moving ? Sounds like an engine/drivetrain vibration transmitted
through the frame, but I guess it could be lots of other stuff too.

 

Exactly the kind of change that can effect vibrations, for better or
for worse or just plain different.

Good luck !

 

I was thinking about this recently, too (I've been out of town for a week
and just got back to the NG).

In the past, when revving the engine in neutral to sync the carbs, I have
seen the tach (Drag Specialties, bar mounted) vibrate as I hit 3000 rpm.
I've thought nothing of it other than a V-twin quirk. It could be that the
vibration has gotten strong enough to be felt (or I'm just now conscious of
it .

But must say that the vibration I feel NOW, is a pulsing vibration that
comes and goes within a 12-15 second interval: everything feels fine, then
the bars will begin to vibrate, and then subside to no vibration. The
looser I hold the bars, the more accentuated is the vibration. If I drop
down to 2500 rpm I don't feel anything in the bars.

Best regards,

Manjo

 

If it tracks a given RPM then I'd definitely look hard at the
engine and bar mounts.

My bike has a well known vibration at about 4000 rpm. The suggested
fixe is to torque the engine mount to 64 ft/lbs, which is quite
a bit more than you might expect.

I'd also take a long look at the bar mounts, yokes and frame. Drag
out the manual and a torque wrench and torque everything in sight
to the actual spec. I'm getting a lot more conscientious about this
lately and it seems to help. Also, if the bars or engine are rubber
mounted for viration isolation I'd consider swapping the mount rubbers.

Finally, the standard question: What was the last thing you did to
it just before the problem started ?