2002 Vstar 1100 is bottoming out with passenger

Replace the spring with a heavier duty should do the job.
Have you tried adjustments in the spring load to stiffen it up.
The rear shock on your Yamaha V-Star 1100 motorcycle assures that the rear wheel is always in contact with the ground and makes your ride much more comfortable by absorbing road vibration and shock while you ride.

But your shock needs to be adjusted for different riding styles, so depending on whether you ride fast or cruise slowly and how quickly you take turns, you may want to adjust the shock to get the most out of your ride.

1

Remove the passenger seat by loosening and removing the rear passenger seat mounting bolt with a socket wrench.
With the passenger seat removed, you should see two larger rider's seat mounting bolts.
Remove these bolts and pull the rider's seat off of the bike to expose the internals of the motorcycle. 2

Detach the quick-release clips of the ignitor unit found just beneath the seat using a screwdriver. Pull the ignitor unit up and to the right of the bike to move it out of your way.

Remove the mudguard quick-release clips in the same fashion, then pull the mudguard out of the bike to expose the rear shock adjuster. 3

Look for the small numbers on the rear shock adjuster.
On most 2002 V-Stars you should see the numbers 1 to 9 printed on the shock adjuster.

These numbers give you an idea of the current setting of the shock.
The higher the number, the stiffer the adjustment. 4

Loosen the shock by turning the shock adjuster counterclockwise to a smaller number using a spanner wrench.

This makes the shock softer and more forgiving when riding over bumps and uneven pavement, but will feel slower in turns and accelerations.

Tighten the shock by turning it clockwise to a higher number.
This makes the shock stiffer, increasing road response in turns and giving you a better feel of road conditions at the expense of comfort. 5

Replace the mudguard, ignitor unit, rider's seat and mounting bolts, and the passenger seat and mounting bolts.

Take your bike for a ride to feel the difference a turn of the shock adjuster makes.