I now have 18 miles on my foreman and I think my valve are knocking already. I'm not sure but it sounds like it to me. Remember it's my first quad and I don't have any idea what they should sound like. Is it normal and should I not worry about it and wait til I have 20 hours and do the first service or take it in now? I know it would be hard to tell just by what I "think" I hear.