How to Adjust the Suspension on My Yamaha R6 Sportbike

The Yamaha R6 Sportbike uses a Graves hydraulic coil-over-shock on the rear. The setup comprises a great shock with a short spring with hydraulic control, which results in smaller amounts of controlled reflex for better recovery. Like all coil-over-shocks, the Graves can lose its adjustment when used heavily. When the rear shock becomes softer than normal, the preload on the spring must be adjusted. It is not a difficult task; however, it requires a spring compressor.

Instructions

1

Raise the bike with the lift until the rear tire is just barely touching the ground. Remove the upper and lower through-bolts and nuts with a socket. Pull the shock out. Place the spring compressor on the spring and compress it until it no longer touches the lower cap; in other words, until it is free to move slightly up and down between both mounting surfaces.

2

Push the C-clip from its groove in the end of the shock opposite the hydraulics. Lift off the spacer and spring seat. Lift the spring off the shock. Loosen the pressure on the spring compressor so the spring can expand. Remove the spring compressor. Measure the spring with the caliper and make a note of this measurement of unsprung length.

3

Install the spring once more, along with the spring compressor. Compress the spring enough to place the spring mount and spacer with enough room to install the C-clip. Release the tension on the spring and allow it to expand between the spring seats.

4

Measure the spring now that it is compressed between the spring seats. Ideally, the spring must have 13 mm of preload. If, for instance, the difference in the two measurements was only 9 mm, insufficient preload is present. The spring must have the preload increased by 4 mm.

5

Repeat the process of compressing the spring and removing it from the shock. Lay the spring aside for now and tip the shock upright. Slide the hydraulic chamber off the shock to expose the ring under the chamber. Turn the ring by hand, clockwise, to increase preload and the reverse for reducing the preload. One turn equals 1 mm. In this case, the ring must be turned four turns clockwise to increase the preload. Slide the hydraulic chamber back on the shock. If the preload needed was more or less than a millimeter, a hex head can be used in the adjusting hole in the hydraulic chamber for small increments of adjustment, such as a half a millimeter or less.

6

Install the spring as before and release the tension. Measure the spring once more, now that the preload has been increased. Its compressed or loaded length should be 13 mm less than its unloaded length. If it is off by more than a fraction of a millimeter, repeat the process.

7

Install the shock by installing the upper bolt first. Lower the bike, little by little, until the lower frame bracket is aligned with the lower mounting hole in the shock, and install the through-bolt and nut. Remove the bike from the lift.