why would a crf 450 carb need a throttle slide plate?

[mx Eli]

I am looking at a quad that needs a throttle slide plate and the o ring. is there any reason that it would need it? I was thinking if it was just from wearing on the carb but I'm not fimiliar with fcr carbs.

thanks for your help

[rt20ps]

I've seen that o-ring missing on another FCR. I don't know what caused it or where it went. The customer swore he never had it apart.

Dirt is probably the only thing that would wear out the plate.