Study,
I'm assuming you don't have a manual. My manual say's to losen the lower nut of the two nut's that you adjust the tension with. After loosening the lower nut stick a narrow punch or screwdriver in the hole in the center of the adjustment nut's and push downward on the tensioner assembly. this should get you the slack you need.
atczack
1985 Honda ATC 250 Big Red
"Ugly Betty" from the handlebars back it's a
1982 Honda ATC200es, from the handlebars
forward it's a 1988 Honda TRX 300 Fourtrax.
"If you wanna play, you gotta pay..."