I've heard that the throttle on the 400ex's aren't adj right, i.e. don't open to their full capacity, how do i inspect to see if my 400ex needs to be adjusted and how do i do it

 

To make sure the throttle is opening all the way, you can do this:
Remove the air boot from the carb. Look inside the carb, make sure the slide that goes up and down is completely out of view when at full throttle.
To adjust if need be, pull back rubber boot on throttle cable at the thumb throttle. Loosen lock nut, turn cable counter clock wise til you have no less than 1/8" play in thumb throttle. Tighten lock nut.
You're done.
If this is too confusing, e-mail me and I'll try to clear it up.

Good luck..ours were adjusted OK.

Later....Sher