My bike does not have one of those can looking things, I think they are for adjusting rear suspension. Idk if it is a stock rear spring or not. Is that piece important. Do some different suspension systems not need one? I dont really know much about them but just wanted to know if i should be worried or not.

 

That "rear can looking thing" is a resevoir, it has an adjuster on it, it is only on the 94 F2 and up CBR models (F3, F4 etc)

 

unfortunately it is a 94. Is there any reason it would have to have a reservoir?

 

Take a picture of it, maybe you have an aftermarket race shock... Or for some reason a pre-94 shock