Hi I own a madforce and it is driven by a chain! I love it!

After some research I found out many other rc had chains too..
For my next build I need a longer chain of the same type...

How do shop for a longer chain or just a chain link to adjust the length?

This is what im looking for... how do I find the rize size pitch

Just buy another Kyosho chain and add as many links as you need. The pics I've seen show the stock chain has a "master link" (the one in your pic) which makes it easier. A chain tool makes disassembling and reassembling the chain easier but it can be done without one too. If you google "chain pitch" you'll find lots of links to determine chain pitch and how to work on a chain with and without a chain tool. This is an Rc application though so I doubt the chain was made to industry standard sizes but I could be wrong.