MX Simulator

IS using the clutch good in racing supercross if so...how would i set up my xbox controller to use the clutch?????

The clutch is VERY important. You need it for...
1. Starts/launches.
2. Slipping (fanning) the clutch to keep the engine from bogging coming out of tight turns.
3. Pulling the clutch in can save you from a swap/highside/tankslapper.
4. Pulling the clutch in during rear braking helps with #2.

I think typical button assignment would be default console settings like L1 or R1.
Whatever is most comfortable. If you used the clutch in a console MX game, try that same button.
Have fun with your new clutch!

The same setting as reflex will work

I like having my clutch as an analogue control so I can slip it better so I have it set to the x-axis of my right analogue stick. Obviously the left trigger would be more natural but I have my throttle on the right trigger so it's not possible.
Just experiment with whatever you feel is most comfortable (I'm by no means a fast guy as you might tell so maybe this isn't the most efficient set-up)

I use it on starts, and when I brake tap in the air. With being able to bang gears instantly, and whenever you want, it's pretty foolish to try to use the clutch to keep the bike in the powerband.

The only other time I've ever used the clutch was in trying to set fast laps, I'd use it under braking in the whoops to keep the back end from swapping, and hit the whoops in 3rd-4th gear... But I find myself too inconsistent with it to ever try it during a race.