1978 250 CR Chain guide

I am wondering how the chain guide is secured to the swinging arm. Should the securing bolt be fully tightened or left slightly loose to allow the guide to move? How should it be set up?
Cheers

Tightened not left loose. It has a rubber bushing that the bolt goes through that will allow the chain guide to pivot if you hit something while riding and return to the normal position. I like to angle it back some toward the sprocket not straight down.

Marty

Thanks for your info.