Author Topic: Bouncy feeling  (Read 4496 times)

Offline Goat

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Bouncy feeling
« on: April 06, 2017, 09:55:52 AM »
I just got my bike back and notice that when I come to slow stops the front seems to bounce, under hard braking full compression this doesn't occur.  The previous owner replaced the front brake pads 1K miles ago.  Is this a function of the suspension settings or something else?  Any suggestions appreciated.

Offline lather

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Re: Bouncy feeling
« Reply #1 on: April 06, 2017, 11:20:01 AM »
I am generally clueless about suspension but I think that under hard braking compression damping would prevent front end dive but maybe not on slow breaking. I would try increasing fork pre-load.

But I gotta ask: You say you just got the bike back - from where? Service?

Changing brake pads should not have any noticeable effect on suspension
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Offline Goat

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Re: Bouncy feeling
« Reply #2 on: April 06, 2017, 02:00:02 PM »
It's a great story.  I bought it new in 09 but had to sell for medical reasons in 12.  Eventually got back on a bike a ZRX 1200 but now have a 100 mile commute so I needed something like a C14  Looked on CL and there mine was for sale, talked with the guy and we traded last Saturday.  My C14 is back home!  :banana

I concur that the pads shouldn't make a difference in suspension but definitely wanted to ask those more experienced than me.  I will give the pre-load a shot, thanks for the input!

Offline VirginiaJim

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Re: Bouncy feeling
« Reply #3 on: April 06, 2017, 02:47:46 PM »
If anything, the suspension is usually quite stiff unless you are security squad sized.  Possibly the previous owner mucked about with either the suspension settings or fork maintenance.  Kinda hard to tell.  Do you still have the owner's manual?
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Offline maxtog

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Re: Bouncy feeling
« Reply #4 on: April 06, 2017, 03:10:43 PM »
I am generally clueless about suspension

I am totally so
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Offline Daytona_Mike

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Re: Bouncy feeling
« Reply #5 on: April 06, 2017, 07:02:52 PM »
I am generally clueless about suspension but I think that under hard braking compression damping would prevent front end dive but maybe not on slow breaking. I would try increasing fork pre-load.
Do not increase fork  pre-load.  You need to know what your doing before you do things like that. Pre-load  is a function of  ride height / chassis geometry and has nothing to do with hard or softer or  helping with bouncing or bad shocks or brake issues .  All your doing by increasing fork  preload is jacking the front up higher which will  cause   more difficult  turn in (you moved the weight distribution from the front wheel to the back wheel)  and  more instability making things worse than they already are.
I think you need to describe 'bounce' better . Maybe your trying to say that  your brake rotors  are warped which causes 'pulsating'? Stock rotors warping are not uncommon on these bikes.  Brakes pads not properly installed  and not  bedded in correctly  can also cause 'pulsating'. Both of those issues disappear under hard braking.
Maybe it is time to have your forks check /serviced. When was this last done?
Some more discussion and investigating  is needed before  diagnosing and effecting repairs.  Blindly shot-gunning is not a good idea.
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Offline Goat

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Re: Bouncy feeling
« Reply #6 on: April 06, 2017, 07:23:05 PM »
Maybe better described as that feeling when you squeeze the brake, let off, squeeze again etc. causing the front to pulse up and down.  This only occurs when on the brakes otherwise it's very smooth.  My new front end stand came this evening and I will lift it up to spin the front wheel and see if a rotor is warped. 

I'm pretty sure the previous owner did adjust settings, he's about 130 with full kit whereas I'm 230 ish with full kit meaning I will definitely be adjusting some.  Need to get this sorted first.

Offline maxtog

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Re: Bouncy feeling
« Reply #7 on: April 06, 2017, 09:34:25 PM »
I'm pretty sure the previous owner did adjust settings, he's about 130 with full kit

Wow- and I thought I was the infamous light-weighter at 145 pounds with NO gear.   From my very limited understanding of bike suspension, there really isn't a whole lot you can do when you are too light (like me) with adjustments.  It really requires replacing the springs with lighter springs.... something neither easy nor cheap.  So we typically just suffer with a harder ride.  Meh, I am used to it.
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Offline connie14boy

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Re: Bouncy feeling
« Reply #8 on: April 08, 2017, 08:13:51 AM »
I just got my bike back and notice that when I come to slow stops the front seems to bounce, under hard braking full compression this doesn't occur.  The previous owner replaced the front brake pads 1K miles ago.  Is this a function of the suspension settings or something else?  Any suggestions appreciated.

You need to get with someone who knows how to do a proper "sag set". I had mine done by someone for $100. who did WERA/CCS racing. Don't go willy-nilly with the pre-loads, etc. by yourself. You will end up with an evil bike. Along with tires, this is very important for this heavy beast if you plan on using it as it was intended.

Offline just gone

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Re: Bouncy feeling
« Reply #9 on: April 08, 2017, 08:54:09 AM »
I just got my bike back and notice that when I come to slow stops the front seems to bounce, under hard braking full compression this doesn't occur. 

Maybe better described as that feeling when you squeeze the brake, let off, squeeze again etc. causing the front to pulse up and down.

My new front end stand came this evening and I will lift it up to spin the front wheel and see if a rotor is warped. 

My first thought was perhaps the stem bearings were loose or damaged then when you explained it more it started sounding like brake rotors might be warped. Since you are checking in to that,
now my next thought is the rotors might need cleaning. Take some brake parts cleaner and some scotch bright (the green stuff that is on back of a scrubbing sponge) and go over the rotors inside and out to make sure you've got all the brake pad deposits off. (yeah, it's a tedious pain in the rear). I've done it several times and it usually makes them nice and smooth for a few hundred miles until I stop on a hill again with hot rotors. Then I get deposits again either with stock or EBC pads, doesn't seem to make much difference. For my kind of riding I'm getting used to it and lazyness helps so I just accept the pulsing, for someone that pushes it and uses trail braking deep into the corners they would most likely need much more smooth feedback and would probably change out the rotors and pads to something less deposit prone.

Offline Goat

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Re: Bouncy feeling
« Reply #10 on: April 10, 2017, 06:00:57 AM »
So I set the suspension where I had it when I owned it before and went for a ride, much better but the "bounce" is still there although not as bad.  Man the settings were all over the place, 7 lines on right fork and 5 on left.  I used stand to look and did not see any discernible warping so the next step is to scrub the rotors with scotch pad (thanks for the idea FartyMarty) and see what that does.  At least it handles much better.   :)


Offline Diablo6v

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Re: Bouncy feeling
« Reply #11 on: April 10, 2017, 12:40:30 PM »
From The "other" forum..I hope this helps you out... ;D ;D

Adjusting Suspension on a Kawasaki Concours 14

The steps provided below were summarized and adapted for the Kawasaki Concours 14 using the excellent instructions provided on the Go Star Racing (How I set up my Motorbike) website:

http://www.gostar-racing.com/information/motorcycle_suspension_set-up.htm

I would highly recommend reading through those more-detailed instructions before simply using the distilled instructions I have provided below.

When setting up the suspension, you will adjust the rear preload, front preload, front damping, and finally the rear damping – in this order.

The Kawasaki Concours 14 does not allow for separate damping of compression and rebound. Therefore, a compromise must be made between the two, as explained in the following set-up instructions.

A. Setting the Rear and Front Pre-load

I.   Adjusting the Rear Pre-Load

1.   Put the bike on the center stand allowing the rear wheel to be suspended in air.
2.   Find a point on the bike directly above the rear axle and measure the distance in millimeters from the axle to this point (The point selected is not important. It is only important to be consistent in measuring from both locations). This is the UNLOADED Distance =_____ mm
3.   Put the bike back on level ground (off of center stand) and bounce up and down a few times. Re-measure from the two points used previously. This is the NORMAL Distance = _____mm.
4.   Sit on the bike in full gear and bounce up and down a few times. Get in your normal riding position with feet on the pegs. Measure the distance between the two points used previously. This is the LOADED Distance = ____mm.
5.   Calculations:

Static Sag = UNLOADED  - NORMAL  = ____mm. This is how much you can lift rear before topping out the suspension. GOAL = 5-10 mm
Rider Sag = UNLOADED – LOADED = ____mm. This is the amount of compression of suspension with bike wt and rider wt. GOAL = 30-40 mm (Ideal – 35mm)
6.   Adjust the rear preload by turning the black knob on the left side of the motorcycle near the passenger peg. Turn clockwise to increase preload (reduce amount of Rider Sag) or counter clockwise to decrease preload (increase Rider Sag). Record total Rear Rider Sag = ____mm.
7.   Re-check the Static Sag (although not adjustable) to see if it remains between 5-10mm. If greater than 10mm, you may need a stiffer rear spring. If less than 5mm, you may need softer springs for your weight.
8.   If Static Sag is less than 5mm, you must compromise and re-adjust the pre-load to give 5mm – to prevent topping out.
9.   To record the final pre-load setting, either rotate the pre-load adjustment knob fully in or fully out while counting the number of clicks to reach either extreme. Return the knob to the adjusted setting and record the number of clicks. Preload = ____clicks from max (fully clockwise) or ____ clicks from min (fully counter clockwise).

II.   Adjusting the Front Pre-load

1.   Method #1: Stationary Static/Rider Sag Method (not recommended)

A.   A. Put the bike on the center stand allowing the front wheel to be suspended in air.
B.   Find a point on the bike directly above the front axle, along the angle of the fork, and measure the distance in millimeters from the axle to this point (The point selected is not important. It is only important to be consistent in measuring from both locations). This is the UNLOADED Distance =_____ mm
C.   Put the bike back on level ground (off of center stand) and bounce up and down a few times. Re-measure from the two points used previously. This is the NORMAL Distance = _____mm.
D.   Sit on the bike in full gear and bounce up and down a few times. Get in your normal riding position with feet on the pegs. Measure the distance between the two points used previously. This is the LOADED Distance = ____mm.
E.   Calculations:
Static Sag = UNLOADED  - NORMAL  = ____mm. This is how much you can lift front before topping out the suspension. GOAL = 25-30 mm
Rider Sag = UNLOADED – LOADED = ____mm. This is the amount of compression of suspension with bike wt and rider wt. GOAL = 35-48 mm
F.   Adjust the front preload by turning the screws (with rings) on top of the forks. Turn clockwise to increase preload (reduce amount of Rider Sag) or counter clockwise to decrease preload (increase Rider Sag). Record total Front Rider Sag = ____mm.
G.   Re-check the Static Sag (although not adjustable) to see if it remains between 25-30mm.
H.   If Static Sag is less than 25mm, you must compromise and re-adjust the pre-load to give 25mm – to prevent topping out.
I.   Record the final pre-load setting, by either recording the number of rings on the adjustment screw or the length of the screw protruding from the forks. Preload = ____rings or ____mm from _________ to _____________.

2.   Method #2 (Recommended “Real World” Method)

A.   Wrap cable ties around the smooth part of the forks (clip off excess). Do not make too tight to avoid damaging the rubber seals.
B.   Slide ties up against rubber seals and take the bike out for a road test.
C.   Ride in normal driving situations making sure to involve cornering, braking and other “typical” driving conditions for the driving you routinely do.
D.   Stop and measure the distance of the tie from the bottom of the fork tube.
E.   If the ties are less than 10mm from the bottom (bottomed out), increase the pre-load by turning the lined nuts on top of the forks clockwise. If the ties are more than 10mm, decrease the pre-load by turning the ringed nuts counter clockwise. Adjust in small (one line) increments, slide the ties back against the rubber seals, and re-test. Always set the forks at the same setting.
F.   Record the final setting. Preload = ____rings or ____mm from _________ to _____________.

 
B. Setting the Front and Rear Damping

I.   Damping – Compression and Rebound (Overview)

A. General Information
-Unlike pre-load, damping really comes down to personal preference – with some safety considerations as well. Overall, it depends on the bike, your riding style, the tires, the tire pressure, the tire shape, etc.
-On the Kawasaki Concours 14, damping is a compromise between compression and rebound, since they can not be adjusted separately.
-If you run out of damping during adjustment (max in or out), you may need to change fork oil for your style of riding.
- Among other things, the bike will handle differently under high and low speeds and wet and dry roads. Damping may need to be adjusted for different conditions.
B. Compression
-The goal is to compress the front in a slow and controlled fashion. The forward weight transfer helps slow the bike quicker.
-If too hard, the bike will skip or chatter over bumps. You can’t compress fast enough, which results in compromised ride and braking – especially in wet conditions.
-If too soft, the bike feels “vague” (poor feedback) and the suspension may bottom out.
-When set correctly, the front compresses in a controlled, predictable manner, which shortens the wheelbase and allows for faster, more predictable, cornering
C. Rebound
-Controls the rate at which the bike “sits-up” after compression. Proper adjustment is critical in corners and turns.
-If set too hard, the rider experiences a lack of feedback and the suspension can continue to “pump down” until the forks are bottomed-out, which is extremely dangerous
-If set too soft, the front-end will pop-up resulting in a loss of traction.
 

II.   Adjusting the Front Damping

- If the front damping is not done correctly, the bike will either sit-up too quickly (too soft) and drift out (washes out) or turn in too quickly (too hard) and feel “wooden.”

1.   Method #1 (Simplistic – not recommended)

A.   With the bike held level, press on the steering yoke, without holding the brake, and then let go.
B.   Observe the distance the yoke travels and the time it takes to return to the starting position.
C.   If it takes longer than 1 second to return to the starting position, decrease the rebound (black knob on top of forks counter clockwise).
D.   If it takes less than 1 second or goes beyond the starting position, increase the damping (black knob on top of forks clockwise).
E.   To record the final front damping setting, either rotate the damping adjustment knob fully in or fully out while counting the number of clicks to reach either extreme. Return the knob to the adjusted setting and record the number of clicks. Front Damping = ____clicks from max (fully clockwise) or ____ clicks from min (fully counter clockwise).

2.   Method #2 (“Real World” Method)

A.   Take the bike out and find a good road for cornering (Sweeping back roads).
B.   Since most accidents happen during cornering, we are going to set-up the suspension for cornering. Goal is to get the bike to enter and exit corners with minimal rocking or see-sawing.
C.   When set-up correctly, the rider will be able to brake hard before a turn or at the apex of a turn, let go of brakes, and get back on the throttle without the bike see-sawing (Sit-up or Dive)
D.   Ride through a series of turns making note of the bikes tendency to rock or see-saw. Adjust the damping one click at a time (some do this over days of riding) to see how the change affects the handling and comfort (feedback).
E.    Once you find the handling and comfort that fits your riding style, record the final front damping setting, by either rotating the damping adjustment knob fully in or fully out while counting the number of clicks to reach either extreme. Front Damping = ____clicks from max (fully clockwise) or ____ clicks from min (fully counter clockwise).


III.   Adjusting the Rear Damping
A.   Background

a.   Compression
-   If the rear damping is not done correctly, the bike will be too bouncy (too hard) or will exhibit excessive squatting (too soft) on hard acceleration.
-   Some squatting (compression) under acceleration is required to ensure good traction, but too much leads to poor exiting from corners.
-    Too soft and the nose will come up and cause the front tire to drift wide on exiting.
-   Too hard and the rear wheel will spin and slip (kicked-up)
b.   Rebound
- When adjusted correctly, the rear wheel remains in good contact with the road for optimal traction.
- When too soft, the chassis will feel unsettled making the bike wallow and lurch mid-corner
- When too hard, the rear wheel will not sit-up quick enough resulting in the nose up and the bike drifting wide, with a vagueness and loss of traction.
 
B.   Setting Rear Damping on a Concours 14

1.   Stand the bike on level ground
2.   Press hard on the foot peg nearest to you.
3.   The bike should compress equally front and back
4.   Adjust the small screw (straight blade) at the bottom of the rear shock (screw faces toward left side). Turn clockwise to increase.
5.   Once the bike is set to compress equally, the suspension adjustments are complete.
 
C.   Notes

-   These instruction were written by a novice (non-professional) and simply represent my attempt at understanding and applying instructions for adjusting the suspension on a Kawasaki Concours motorcycle.
-   An improperly adjusted suspension can result in an accident causing injury or death.
-   Adjustments to the suspension should only be made by someone qualified to make such adjustments
-   Anyone following the instructions provided in this document is doing so at their own risk.

Offline gPink

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Re: Bouncy feeling
« Reply #12 on: April 10, 2017, 04:02:43 PM »
Diablo, when setting sag do you start with the adjustment at a zero setting?

Offline VirginiaJim

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Re: Bouncy feeling
« Reply #13 on: April 10, 2017, 04:14:09 PM »
So I set the suspension where I had it when I owned it before and went for a ride, much better but the "bounce" is still there although not as bad.  Man the settings were all over the place, 7 lines on right fork and 5 on left.  I used stand to look and did not see any discernible warping so the next step is to scrub the rotors with scotch pad (thanks for the idea FartyMarty) and see what that does.  At least it handles much better.   :)

That doesn't inspire any confidence on what he did besides that.  He could have mucked about with the fork fluid as well.
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Offline Daytona_Mike

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Re: Bouncy feeling
« Reply #14 on: April 10, 2017, 08:00:27 PM »
So I set the suspension where I had it when I owned it before and went for a ride, much better but the "bounce" is still there although not as bad.  Man the settings were all over the place, 7 lines on right fork and 5 on left.  I used stand to look and did not see any discernible warping so the next step is to scrub the rotors with scotch pad (thanks for the idea FartyMarty) and see what that does.  At least it handles much better.   :)
You need to spin the wheel to check for warped rotors. You cannot 'look' from a stand. Holding a pencil steady  will work just  not so  accurate..
https://www.youtube.com/watch?v=2GaYqJYhCB0
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Offline Goat

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Re: Bouncy feeling
« Reply #15 on: April 11, 2017, 06:17:42 AM »
Thanks for the link, I'll watch but I did spin it with the pencil.  There is one spot in the rotation where there is a little more resistance than anywhere else however the pencil never really lost contact with the disc. 

"That doesn't inspire any confidence on what he did besides that.  He could have mucked about with the fork fluid as well."

You're right and that has crossed my mind as well, a rebuild is in order albeit just a little further down the line.

Thanks again everyone, I appreciate the ideas and thoughts!





Offline Shoe

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Re: Bouncy feeling
« Reply #16 on: April 15, 2017, 08:31:17 AM »
I would call the previous owner and ask him if he did any suspension adjustments. That might give you a clue. Don't leave out the rear suspension either.
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Offline Goat

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Re: Bouncy feeling
« Reply #17 on: April 20, 2017, 09:56:35 AM »
I would call the previous owner and ask him if he did any suspension adjustments. That might give you a clue. Don't leave out the rear suspension either.

I will do that but I decided to go to a suspension pro to have it set up for me.  This guy is in Austin TX and does setups at tracks on weekends.  Hoping to get in on the 28th and can't wait to see the difference.  In the meantime going back to what I had before has improved it some, it's not bad but I can't wait to get it better!

Offline Goat

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Re: Bouncy feeling
« Reply #18 on: April 25, 2017, 10:17:48 AM »
So I spent some time cleaning the front rotors with a steel brush hoping to cure the bouncy feeling to no avail, they certainly roll easier however.   Not sure of next steps, I have fantastic braking power and its only on slow braking that it occurs, I don't feel unsafe just annoyed.

Should I take the pads out and scuff them up a bit?  They have approx. 1K on them.