Loose chain

i have a vfr 800,with a single swing arm,the chain is very loose and is hitting the center stand,how do i adjust it.

I'm not familiar with that particular bike & haven't been around the type since the earlier 750 Interceptors (when I had an FZ Yamaha), but this is from another forum & should be just the answer you're looking for:

There is a spanner wrench with a flat extension tube in your tool kit. Loosen the pinch bolt at the aft end of the swingarm. Take the spanner wrench and set it into the toothed wheel on the swingarm side of the wheel hub. It works in either the clockwise or counter-clockwise direction, depending on how much adjustment needs to be put in or taken out if you set it too tight. When you have the chain properly adjusted, remove the spanner and tighten the pinch bolt. All done.​