I have a '98 Quadrunner 500 4X4. My adjustment has one locking ring with the adjustment screw on the inside of the locking ring.
Righty Tighty - Lefty Loosey
Turn the big nut so your hand is moving towards the right, if the wrench is at the bottom of the bike pointing down. A half turn should do it. Then turn the little screw in the same direction. Keep the little screw in that position while tightening the lock nut back down. It is a very fine adjustment, and should have only been turned about a quarter of a turn at a time.
After you have tightened the lock nut, and kept your eye on the adjustment screw the whole time, take 'er for a spin.
If you turned it too much, you won't be able to shift upward through the gears.
If you didn't turn it enough, it will still slip, as it does now.
If this machine is an automatic belt drive like a Polaris..... Your best bet would be to try and locate a SUZUKI FACTORY SERVICE MANUAL for it.
Hope this helps, and please post your results here.