Chain Slack

[mysticbluex3]

So according to my manual, the chain slack is suppose to be 46-48mm.  This is from center of chain to the bottom of the swing arm (1/2way between the front and rear sprocket).  However, when I adjust it to 46-48mm, the chain seems really tight with not much slack at all.  I have it set at 50-52mm and that seems more right.  Thoughts?  Its a 09M696.  How much slack should I have (from pushing down on the chain to pushing up)??

Off topic, then the rear shock compresses, does the chain tighten or loosen?