Head shake/tank slap?

I seldom travel below 90, and have been as fast as the bike will go (150) on an Avon Cobra front and BFG G-Force car tire on the rear. No vibration or steering shake like the Metzler started doing halfway worn. Of course I have those "ugly" sticky weights on both sides of my wheels though.
 
Update: Now have Intermittent head shake/tank slap

Front wheel AND tire are now on with proper rotational direction; I added another ounce of Dyna Beads, bringing the total to two ounces for the front tire. Took it back out on the interstate,and the first blast up to 90 seemed promising: NO shake. Coasted back to 70 or so, then did another blast. TERROR: the shake was back!!! :eek:

Summoned up some courage, then tried another run: NO head shake. Did another: no shake. Started feeling a bit better; maybe the first shake was just a fluke.

Then did another blast, and this time the shake returned at 85 mph. Scared the sh__ out of me!!

I am puzzled: why the shake, and why is it present sometimes, but not others???

Only other clue is that the cleaner the air, the less likely it is to shake. Turbulent air on the interstate seems to make the head shake more prevalent.

Next step: take off the new Shinko altogether, and put my almost-worn-out Metzler back on. Then see what happens.

I'll keep y'all posted. In the mean time, I'll stay below 80 mph, just to be safe.

CW
 
CWCobra said:
Front wheel AND tire are now on with proper rotational direction; I added another ounce of Dyna Beads, bringing the total to two ounces for the front tire. Took it back out on the interstate,and the first blast up to 90 seemed promising: NO shake. Coasted back to 70 or so, then did another blast. TERROR: the shake was back!!! :eek:

Summoned up some courage, then tried another run: NO head shake. Did another: no shake. Started feeling a bit better; maybe the first shake was just a fluke.

Then did another blast, and this time the shake returned at 85 mph. Scared the sh__ out of me!!

I am puzzled: why the shake, and why is it present sometimes, but not others???

Only other clue is that the cleaner the air, the less likely it is to shake. Turbulent air on the interstate seems to make the head shake more prevalent.

Next step: take off the new Shinko altogether, and put my almost-worn-out Metzler back on. Then see what happens.

I'll keep y'all posted. In the mean time, I'll stay below 80 mph, just to be safe.

CW
Click to expand...

the issue is probably the loose spacer fit between the front forks...


loosen the pinch bolts, the push up and down on the front forks via the handle bar... then just snug up the pinch bolts. go get a soft face rubber mallet. gently drift the forks together till they're snug against the spacers. this is best done while tapping against the pinch bolt side while hand holding the other side. then tighten pinch bolts and go for a ride... repeat if needed.


greg
 
I'm sure the fact that the wheel weights are rolling around loose inside the tire has NOTHING to do with it. :rolleyes:

When as little as 1/16th of an ounce can balance a tire what are the odds of moving weights landing in the right spot every time you stop and go again? Pretty slim.
 
I just had a new set of Metzlers installed. Took it out for a couple of hundred mile scuff in ride this morning. On the way home I ran it up to 110 to see how it felt. A bit of a weave set in at 110 and lasted down to around 90. A couple of miles further down the road I tried it again and it was steady to 112. On the R3T with the fork mounted windscreen and the bags, anything over 100 can bring on that weave if the road isn't just about perfect. Not scary, just noticeable.

Assuming everything else is sound, it really sounds like you have a balance issue. Before swapping tires, I'd take it to a shop and have it balanced using wheel weights.
 
GPMAZ said:
Old age. By the time I got around to ordering the tires, I forgot to check on the Dunlops. I have a note taped to my forehead for next time. :(
Click to expand...


Well atleast you have more choices than I have. I have to use rear tire size of 240/50/16 for my Roadster. My choices are Avon or Metz :(
 
goodfellow said:
the issue is probably the loose spacer fit between the front forks...


loosen the pinch bolts, the push up and down on the front forks via the handle bar... then just snug up the pinch bolts. go get a soft face rubber mallet. gently drift the forks together till they're snug against the spacers. this is best done while tapping against the pinch bolt side while hand holding the other side. then tighten pinch bolts and go for a ride... repeat if needed.


greg
Click to expand...

After having the front tire off and on several times, I'm having trouble understanding...the axle bolt, when tightened, pulls the forks together against the spacers. Then the pinch bolts hold it there. Maybe what you are saying is that I may not have torqued my axle bolt tightly enough. If that's what you are saying, that would make sense. A loose axle bolt might allow the wheel to "wander" enough to cause a high speed wobble. Sounds reasonable. Anbody got a quick reference to the shop manual to tell me the torque spec. (in foot-pounds)? I've cranked it down about as tight as I can with my standard socket wrench. Maybe I need to torque it some more with an 18" breaker bar instead. Sure couldn't hurt a thing. Be very funny if that was my trouble the whole time, huh!!
 

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