Ok, your in England so I can’t help you on where to get parts. But I can help educate you. Go to the Go Kart Supply website and look up chains, clutches and CVTs and read up on all that stuff. The short answer to your question is return that clutch and get one for #35 chain with 10 teeth or better yet switch to a CVT 30 series TAV II and use a Genuine Comet Belt. Read that stuff and come back if you have any questions or happen to fix it. If your tires are over 10” tall you should switch to a CVT. Best advice I can give. Give a man a fish and he eats for a day. Teach a man to fish and he eats everyday! (Unless your like me and a lousy fisherman.)