Use your spark plug wrench to adjust your rear suspension
if you take apart your head gasket and then replace the oil pump then you might not even have to adjust your suspension
paioli front forks and marzochi rear monoshock
you don't computer controlled, or replace the suspension (shudder) expensive.
As long as its Not a yz model blaster.
there is no way to adjust the ride height other then aftermarket suspension parts
All you can adjust is the preload. You need a spanner wrench. http://www.xs650.com/forum/
It is a valve in the brake lines going to the rear of the vehicle. It adjust the amount of fluid flow to the rear brakes depending on the height of the rear suspension. The lower the suspension, the more weight in the vehicle, the more rear braking power is needed.
To adjust the rear suspension on a mountain bike for optimal performance, follow these steps: Determine the correct sag level by measuring the amount of suspension travel used when sitting on the bike. Adjust the air pressure or preload to achieve the desired sag level. Fine-tune the rebound and compression settings based on your riding style and terrain. Test the suspension adjustments on different trails to find the optimal setup for your riding preferences.
Sounds like you may have broken rear suspension parts. Sway bar or spring may be broken.
you take it to alignment shop and have them adjust it after they take measurements.
Most Montana's have a rear air suspension in them (air shocks). The compressor is there to adjust the rear height of the vehicle depending to weight in the van.