Suspension - Rear : Kawasaki ZX Forums: Kawasaki Ninja Forum

Wozza · 06-26-2009, 01:08 AM

Alright Lads and Ladies,

Right I bought a ZX12R about 6 weeks ago. Now the problem i'm having is that the rear is too stiff/ hard... When I go over any bumps/ pebbles it feels like the back tire is flat...

I have adjusted the Rebound Dampening at the end of the strut (All the way to the left/ Soft) and have also adjusted the Compression Dampening to soft also (gas reservoir all the way to the left/ soft)... still no joy.

Is there a rubber bushing/ mount anywhere on the rear strut that may be damaged.

The reason I say is that the lad I bought it off was a big/ heavy dude (no offence if he's reading this) and both settings were set to hard..

Any clues?

Cheers
Wozza

Hammerhead · 06-26-2009, 04:32 AM

You also need to back off the spring preload. All damping does is attempt to control repetitive bouncing. The spring actually carries the weight and the higher the preload, the stiffer the spring.

honestlyinsane · 06-26-2009, 04:42 AM

agree with hammer head you need to set the proper sag for your weight by adjusting the rear spring.

Wozza · 06-26-2009, 05:00 AM

Okay. Well strut is showing about 10 threads. Is the spring
Compressed too much. I weigh about 16st and about 6 ft 4in
Height.
Thanks for replies.

W

BLUE ZX9 · 06-26-2009, 06:47 AM

Looked in the manual factory setting is 6.77in from face to face of spring. This is out of a 2000 manual should be the same?

honestlyinsane · 06-26-2009, 10:21 AM

Quote:

Originally Posted by Wozza

Okay. Well strut is showing about 10 threads. Is the spring
Compressed too much. I weigh about 16st and about 6 ft 4in
Height.
Thanks for replies.

W

Instead of guessing just set sag. measure the height of the rear of the bike then re measure after you sit on it . I usually set mine about 1 1/2 to 2 inches of sag. I am not sure what the proper setting of sag is on the bike.
I am not sure what 16 stone is in pounds but I will go look at my bike and see how much I have showing.

Wozza · 06-26-2009, 10:29 AM

16 st is 225 pounds.

mad · 06-27-2009, 03:47 AM

Quote:

Originally Posted by honestlyinsane

Instead of guessing just set sag. measure the height of the rear of the bike then re measure after you sit on it . I usually set mine about 1 1/2 to 2 inches of sag. I am not sure what the proper setting of sag is on the bike.
I am not sure what 16 stone is in pounds but I will go look at my bike and see how much I have showing.

Proper sag range is 25 (track) to 35 (street) millimeters front and rear.

Wozza · 06-29-2009, 03:24 AM

Right, measured sag...

Off bike... 39.75 Inches (1009.65mm)
On Bike.. 38.25 inches (971.55mm)

1 and half inches of sag...

clarkmanning · 06-29-2009, 04:46 AM

Maybe suspension is bottoming out? Too much sag?

Wozza · 06-29-2009, 07:16 AM

Right, just took a pic of strut... 10 threads showing...
Where the gold paint stops and silver paint begins on threads, would this be the standard position of the height of the 12R i.e. 3 -4 threads showing????

Thanks

W

Wozza · 06-29-2009, 07:18 AM

Quote:

Originally Posted by clarkmanning

Maybe suspension is bottoming out? Too much sag?

Yes I was thinking this... the spring maybe compressed too much causing it to compress against itself... have a look at pic...

W

honestlyinsane · 06-29-2009, 05:51 PM

I counted mine and it only has 7 threads showing and I am similar weight. I cranked mine a little more because I lowered the bike and I ride 2 up alot and the bike was bottoming out am guessing only 5 threads were showing from factory setting.

Wozza · 06-30-2009, 12:44 AM

Quote:

Originally Posted by honestlyinsane

I counted mine and it only has 7 threads showing and I am similar weight. I cranked mine a little more because I lowered the bike and I ride 2 up alot and the bike was bottoming out am guessing only 5 threads were showing from factory setting.

Cheers for this...
What I'm going to do is bring it back up to 5 threads... after this, if it feels better, then I will play around with the dampening/ rebound etc etc...
Trial and Error begins.
Cheers for all replies lads...
W

zzr lon · 07-15-2009, 08:14 AM

not wanting to state the obvious but are the linkages all good and well greased as a solid rear is what a rusted suspension feels like and your shock looks quite old to so worth checking or changing

mad · 07-15-2009, 05:24 PM

Quote:

Originally Posted by zzr lon

not wanting to state the obvious but the linkages are all good and well greased as a solid rear is what a rusted suspension feels like and your shock looks quite old so worth checking

Agreed. Shocks are usually ready for a rebuild around 20,000 miles or so.