Question on installing Primary Drive front sprocket

My front sprocket (I assume is OEM) has a hard rubber ring around the back and two hard rubber half moons on the front.  They don't appear to be removable and the Primary Drive front sprocket doesn't have them.  Do I need to install some sort of spacer behind the Primary Drive sprocket?  Does this affect the alignment of the chain to the rear sprocket?  

I'm riding a 2008 wr250r

This is what the sprocket on my bike looks like (rear view)


This is what the primary drive sprocket looks like (no rubber on either side)


This is what the repair diagram shows:

I believe all that extra stuff on the stocker is there for noise and vibration control.

Just throw the new one on and check the alignment. You should be good to go.

I've had a Primary Drive sprocket on my X for years now.
No additions or mods needed.
Mount it and enjoy.

yep i tossed aside the rubber crap, the bike is heavy enough as it is

also #29 on your parts list will wear out over time