Adjusting the Pre-load of a suspension changes a lot of characteristics of a motorcycle like ride height, cornering feel, overall angle, body position, suspension travel so on an so forth. With use and time, suspension springs lose their strength and they become 'loose' or weak, which can also be corrected by suspension pre-load adjustment. Some motorcycles (like my Vstrom 650 XT) has a remote hydrolic controlled pre-load adjuster which just makes the job too easy, however most Indian motorcycle do not have that. But almost all suspensions these days have pre-load adjustment option.

Step 1 : For Yamaha Fz v2.0 / Fazer FI, remove the wheel-hugger. For other bikes, remove any wheel-hugger or similar port which restricts the reach to the rear suspension.

Step 2 : Secure the bike on the main(center) stand.

Step 3 : Take a C-Wrench (links in video description) and start rotating the adjustment ring on the rear suspension.

Step 4 : Adjust and take a spin to feel the changes and choose the best setting for your bike.

Step 5 : Under no condition should the suspension bottom out, make sure you have enough pre-load for that.

Pro Tip : To reduce ride height (for shorter riders), reduce pre-load, that way the bike bogs down in height when you sit on it.

Follow the below detailed video to see how it's done :