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Tank slapping while cornering

C

cyrusyn

New member
Joined
Aug 28, 2008
Location
SF
Moto(s)
Looking for one.
I have a tank slapping or head shaking issue while making a 90 degree turn at intersections.

Today afternoon, I was making a 90 degree right turn at an intersection. I slowed down to 20 mph and felt that I needed more angle as I approached its apex and I leaned the bike. I yanked the clip on to countersteer and at the instant the bike leaned more the clip ons jerked left and right 4 times in quick successions.

Tire pressures are within spec.

The bike is all stock. Tires need to be changed as it was on the bike for several years and has weird patterns on them although they still have good amount of meat. In my guessing, the front struts also have several years olds fluid in them. By getting new tires and changing front struts' fluid, will this phenomenon be eliminated?

1991 Honda CBR 600 F2
About 30k miles.
Resucitated last year fall from 3 years of garage keeping.
 
dont yank. dont shove. dont grab. push gently, be firm.
 
cyrusyn, you may want to check the headset bearings for either looseness or being worn/damaged. And as the others have mentioned, it will be faster, more managable to push the bar rather than pull. If you want to go right, push the right bar, for counter-steering purposes....vice versa for left :)
 
cyrusyn said:
I have a tank slapping or head shaking issue while making a 90 degree turn at intersections.

Today afternoon, I was making a 90 degree right turn at an intersection. I slowed down to 20 mph and felt that I needed more angle as I approached its apex and I leaned the bike. I yanked the clip on to countersteer and at the instant the bike leaned more the clip ons jerked left and right 4 times in quick successions.

Tire pressures are within spec.

The bike is all stock. Tires need to be changed as it was on the bike for several years and has weird patterns on them although they still have good amount of meat. In my guessing, the front struts also have several years olds fluid in them. By getting new tires and changing front struts' fluid, will this phenomenon be eliminated?

1991 Honda CBR 600 F2
About 30k miles.
Resucitated last year fall from 3 years of garage keeping.
Click to expand...

Well, first you want to get the suspension freshened up, at the very least. Basic service with fluid change, both front and rear. Proper springs if you can spend a bit more, valving if you can spend to fix them proper. I owned/raced/toured on a 91 for 8 years, it's definitely not normal. 30k miles isn't much for those at all. While the forks are off, check the head bearings. Other than that, get some good tires and you'll be hard pressed to get that bike out of shape, at any speed.
 
Thank you very much for all your advices, guys.

Lester Green said:
tank slapper at 20 MPH...get real.
it was something else guaranteed.
Click to expand...

Then understand it as a very violent head shake. This bike gave me head shakes often when I leaned close to 45 degree but never gave a head shake like that before.
 
KazMan said:
cyrusyn, you may want to check the headset bearings for either looseness or being worn/damaged. And as the others have mentioned, it will be faster, more managable to push the bar rather than pull. If you want to go right, push the right bar, for counter-steering purposes....vice versa for left :)
Click to expand...

Head bearing shows no wiggle when I move the top triple tree.
 
cyrusyn said:
I have a tank slapping or head shaking issue while making a 90 degree turn at intersections.

Today afternoon, I was making a 90 degree right turn at an intersection. I slowed down to 20 mph and felt that I needed more angle as I approached its apex and I leaned the bike. I yanked the clip on to countersteer and at the instant the bike leaned more the clip ons jerked left and right 4 times in quick successions.

Tire pressures are within spec.

The bike is all stock. Tires need to be changed as it was on the bike for several years and has weird patterns on them although they still have good amount of meat. In my guessing, the front struts also have several years olds fluid in them. By getting new tires and changing front struts' fluid, will this phenomenon be eliminated?

1991 Honda CBR 600 F2
About 30k miles.
Resucitated last year fall from 3 years of garage keeping.
Click to expand...



BINGO!!
 
Last edited:
cyrusyn said:
Head bearing shows no wiggle when I move the top triple tree.
Click to expand...

U wouldn't feel it that way. You need to get the front wheel off the ground and push/pull at the axle from in front of the bike. ANY perceptable slop is bad. The difference between riding with sloppy head bearings vs properly adjusted ones is very noticable.
 
cyrusyn said:
I have a tank slapping or head shaking issue while making a 90 degree turn at intersections.

The bike is all stock. Tires need to be changed as it was on the bike for several years and has weird patterns on them although they still have good amount of meat. In my guessing, the front struts also have several years olds fluid in them. By getting new tires and changing front struts' fluid, will this phenomenon be eliminated?

1991 Honda CBR 600 F2
About 30k miles.
Resucitated last year fall from 3 years of garage keeping.
Click to expand...


It isn't a "by getting new tires and changing fork oil, will this phenomenon be eliminated?" issue.
Do that stuff because it has to be done. Not doing it is being a hopeless twit.

Don't be a hopeless twit. The hopeless twit will have some disaster sometime somewhere.

But as an interest, after (and I hope you don't choose some garbage tire brand and model when you change to new tires) After you change tires and fork oil, try the same corner, on the same line, and same throttle, and report on how the bike works. :thumbup
 
Definitely I will get back to you with that update. Thank you very much.

louemc said:
It isn't a "by getting new tires and changing fork oil, will this phenomenon be eliminated?" issue.
Do that stuff because it has to be done. Not doing it is being a hopeless twit.

Don't be a hopeless twit. The hopeless twit will have some disaster sometime somewhere.

But as an interest, after (and I hope you don't choose some garbage tire brand and model when you change to new tires) After you change tires and fork oil, try the same corner, on the same line, and same throttle, and report on how the bike works. :thumbup
Click to expand...
 
New tires, very high priority.

New struts, high priority.

Check head bearings, high priority.

Change all fluids, priority.

Any time you, or anyone else, let's a motorcycle, or other vehicle, sit, all of the fluids will likely need to be changed.

Oil, highest priority.
Brake fluid, very high priority.
Clutch fluid, high priority.
Coolant, if you have this, priority.

Keep the rubber side down.
 
cyrusyn said:
I have a tank slapping or head shaking issue while making a 90 degree turn at intersections.

Today afternoon, I was making a 90 degree right turn at an intersection. I slowed down to 20 mph and felt that I needed more angle as I approached its apex and I leaned the bike. I yanked the clip on to countersteer and at the instant the bike leaned more the clip ons jerked left and right 4 times in quick successions.

Tire pressures are within spec.

The bike is all stock. Tires need to be changed as it was on the bike for several years and has weird patterns on them although they still have good amount of meat. In my guessing, the front struts also have several years olds fluid in them. By getting new tires and changing front struts' fluid, will this phenomenon be eliminated?

1991 Honda CBR 600 F2
About 30k miles.
Resucitated last year fall from 3 years of garage keeping.
Click to expand...


Yikes.. That's the CBR self correcting your bad input.. It just saved you..

Anything else would have put you on your face. Closeing the throttle or even throttleing down through corners and leaning more is uh.. flirting with disaster.. slow in... fast out.. stay on the gas.

Your steering head bearings may be loose/notched too.
 
I'd have your suspension settings checked too while you're at it...at one time my old bike was getting squirrelly on me, turned out someone had fucked with it and turned one of the fronts a full turn (or more). Screwed up the handling pretty bad, didn't get exactly what you described, but add in your inputs and it very well may have had a similar reaction.
 
Also make sure your front brake isn't sticking, and that they aren't applying themselves when you turn the handlebars. When you have the bike in the air doing all the maintenence that's been suggested here, spin the front wheel when the bars are straight, at left lock and at right lock and make sure it's smooth.
 
this is city riding correct? isn't it possible that said corner could just have some inconsistencies/debris/bumps that would cause the front to get unsettled, espically at that speed?
 
Worn tires can cause shit like this. Change the tires (since they need to be changed anyways) and see if the problem goes away.
 
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