Most Predator 212cc engines come with a stock jet of .028.
If you are upgrading air filter and exhaust, you'll want to go up in size. Most people use our jet kit and put in a performance emulsion tube as well as either a .036 or .037 jet. Here is the jet kit.
If you are at a higher altitude, you may need to use smaller jets. Here is a link to where you can pick your jets individually.
Honda Clone and Predator 212cc engines take the same jets,