I am doing alot of high, and long jumping on my 400. Is there a way I can stiffen the rear shock? The fronts are fine, but I have bottomed the rear out a couple of times.

 

You can do two things. Increase the "preload", by tightening the threaded ring at the top of the shock, and/or increasing the "compression damping" (screw at the top of the shock, on the "can"). In general, you want your rear to sag about 3", with you sitting on the bike in full gear. Then you can mess with rebound (screw at the bottom of the shock) and compression damping to fine tune the ride.

See:
http://www.off-road.com/atv/suspension/shockadj.htm

 

Thanks brother, I never knew that your bike should sit 3" lower with you sitting on it.