Hello and welcome to the boards

Do you spend alot of time together like going places etc?Maybe you could use the carrot and stick method,tell him if he does well in his exams you will do something to celebrate with him.If you show how much doing well in his exams mean to you he may take notice.The reason i'm saying this is because by your description of your son he is a good lad and not a waster like most are so you are quite lucky really.You could show him a list of jobs he will be doing if he does crap at school too or ask McDonalds if they will employ him for the day if that don't change him I don't know what will.