the screen on the inside of exhaust

it wont hurt it but it is your spark arrestor. if you want to clean it the manual tells you how.

just soak it in some carb cleaner

what does the spark arrestor do

It keeps sparks from coming out the exhaust and starting a fire.

thanks it has a hole in it bout the size of a nickle

you mean it has a hole in the screen or the hole for the exhaust to exit? that screen is just there to catch the sparks that may possibly be in the exhaust system if there is a hole in the screen i wouldnt worry to much about it.

in the screen

i wouldnt worry to much about it, a hole that small in the screen wont matter, its there in case sparks make there way into the exhaust. i havent even had my spark arrestor in for 6 months

Does it matter if you clean it or not????

not really, the manual says to but no one does. public riding places require them. if your exhaust isnt loud i wouldnt worry about fixing it, no one would ever know. if you do want to clean it just do what aastelly said, that will clean it.
-Aaron