How to adjust cam chain

I've narrowed the wierd clacky rattly noises the engine makes (81 GS450) to the cam chain, since they're very random, make different sounds at different times & engine loads, and don't occurr all the time.

Let me preface this by saying THE CLYMER SERVICE MANUAL PHUKKING SUCKS!!! There are so many things missing (like how to tension the cam chain, for example) that the book is basically useless for routine maintenance. For those of you who do not yet own a Clymer manual, don't waste your money. I finally found a shop that sells real Suzuki manuals, so I'm getting one of those in a couple weeks.

Anyway...how do I tension the chain? Anyone have a good step-by-step procedure I can use? I'd like to get it done while the bike is in non-operational status. Thanks!!