engine guards are easy you need to get a floor jack under the engine to relax the weight. you will know you have it right when you can move the front engine mount bolt in and out of the bike with your fingers. it will also spin freely. after you get to this point use the proper torque and your good to go.
Also if your buying used ones make sure you do not get the weak first series of them. They are about as useful as a c_nt full of cold water