I've had the throttle on my 99 Banshee stick open on me a few times. The first time it was when I was going through a lot of mud. But since then, It does it a lot after I wash it. Do you think it could be dirty throttle cables? The TORS has been removed, and I cleaned the Throttle Housing on the handlebars... It's just really annoying when you hit a nice slow jump, and have the throttle WFO when you land!

 

I have seen this before..You have mud/dirt in the cable.. This happened to one of my riding partners after a day in the mud.. He has a 98 Banshee.

 

You failed to specify which type of throttle you have..thumb or twist.If you have a thumb, the preceding post may describe the problem. If it is a twist, it could be the same or you could have the grip too far onto the bars & the end of the grip is rubbing on the bar end