A buddy of mine made the prop spacer so I am not sure what size to tell you to look for. I can find out tommorow and let you know. The spacer is not threaded just slides over the shaft. I have heard of people putting CDI on this one but why bother? Its very light as it is. As for the work on the casing....took me about 5 minutes with my edge sander and it was done. Be careful not to take to much of the ignition bracket off. One of our guys did and weakened it too much.