K1 – Rear suspension Mods
New Linkage (October 2002):
Recently I bought a ’97 ZX7R(P) shock linkage (Rocker and tie rods) and set about installing it on my ’91 K1. With the new rocker the K1’s tie rods would have raised the rear height far too much and given the swingarm too steep an angle with respect to the front sprocket, so I decided to use the P model tie rods instead.
Once it was all fitted the first thing I noticed was that as a result of the more linear rate of the new linkage I now needed an extra 11mm of preload just to get the sag about right for my weight! The rear ride height is now marginally lower, but the steering response does not seem to have suffered (if it had I could have compensated for it with the ride height adjuster anyway).
After setting the sag I went out to test the bike and to find new damping settings to suit the changes.
The bike was instantly miles better. On my first ride out on settings that were not quite right yet, I was able to push through corners with much more confidence and speed.
With the old linkage the shock seemed to be too soft in the initial part of the travel only to suddenly turn rock hard when having to compress further. Now the shock works as it always should have done. The action is firm, but controlled and predictable.
New Shock settings:
|Shock||Preload – mm of thread showing||Rebound – Adjuster settings||Compression – clicks from fully in||Ride Height – Spacer size in mm||Tyre pressure (PSI)|
Please Note that fitting the new linkage and tie rods will lower the rear ride height slightly and You may want to increase the ride height figure in the above setting by 5mm or more depending on your preferences.
I have used the above setup for quite a while and decided that I was going to raise the rear ride height, but I then came across some racekit tie rods. These are longer than the K1 items (which are 17.5cm from bolt eye to bolt eye) and shorter than the P ones (19cm from bolt to bolt). The racekit tie rods are 18.5cm (again from bolt eye to bolt eye) and have the effect of raising the raide height by just the right amount for me. not only that, but, in my humble opinion they bring the linkage to operate in a slightly different range that seems to work better for me.
I cannot give you revised shock setting with the new tie rods as I am now using an Ohlins unit and not the stock shock.
If after performing the above mod you also decide to fit an aftermarket shock make sure you tell the shock supplier about this mod as the new linkage alters the suspension caracteristics of the machine. Even though you should easily be able to adjust a shock meant for the previous linkage to work on the new one, if you are buying new it is worth having the spring upgraded to a heavier type and damping tweaked to suit.
I have just purchased a KA049 Ohlins unit originally intended for a “K” linkage, but valved and sprung for a P model ZX7R (solo riding) as this suits the new linkage far better than the standard KA049. I have not fitted it yet, but as soon as I do I’ll add my impressions and setup info.