scrambler 50 chain tightening

[300ex mxracer]

how do u tighten a chain on a scrambler 50? i dont have the owners manual and my cousin was riding it and the chain came off so im guessin it is too loose.

[Sjorge450R]

there are four bolts on the rear axel in between the sproket and brakes. There are two on each side. Loosen them and then there is a gold screw sticking out the back, tight them to were the chain isnt to tight. (remember it is going to stretch with weight on it) then tighten them bolts and you are good to go. I believe they are 17mm. And the gold screw it a 10mm