New to forum but wanted to start new up to date post on rebuilding 2003 XR100R. Just bought this for my son fairly cheap. It was running rough cleaned carb and adjusted valves only to find a mess in the intake. There was a nest in the air box with seeds of some sort, filter was shot and there was a real sticky yellow mess causing intake valve to stay open. I removed engine after this now going to put bbr big bore on it and replace valves also. Any advice on carb? Upgrade? New jets or anything? I want to do it right for my son also it’s a project for us to do together so It’s meaningful for both of us. Any advice would be great!