Like others have said here, the tools are way too expensive to be a DIY'er for complete rebuilds. In my case, I'm a stubborn old coot, so I bought the tools anyhow. My latest purchase was a used valve grinder. Between buying it and the repairs it needed to get it back in shape, I'll never get my money back. With what tools I own and a good friend of mine own, there's nothing I can't do for a rebuild. I truly enjoy rebuilding these little powerplants and see how well I can make them run, so for me it's worth it. Honestly, karting would be pretty boring for me if I didn't do it that way. It's possible to be a DIY'er but it costs a lot of money to get set up for it, and you're going to trash some parts along the way as you learn. Ask me how I know that......