New to the forums and also new to this quad

I got this 1984 Suzuki LT 250E for free if I could get it running. Sat in the bushes for years so I spent the past few days working on it to get it running. I took it for a test drive and the chain slipped off and whacked the side cover on the engine so hard it blew a hole right through it. My problem now is trying to get a replacement part, but I don't even know what it's called. It came off the left side and the pull cord assembly was attached to it. I have some pictures here of exactly what it is I need so if someone can tell me what it is officially called and maybe where I can find one online that would be awesome. Pics: