Making a "JAIN/JAN" watever u call is pretty easy. Take a small cardboard paper, even tissue box or in my case i used milk paks box and used a scissor to cut it and made holes a bitt smaller and placed it back. Working like a charm. Yes, bigger holes mean more race and small holes will result in low race. Give it a try, it only requires a 8 number key for opening of screws and a card board type thick sheet. Its a simple task so adjust holes as per ur liking for the race