This is a great replacement to the stock petcock for an excellent price. One flaw is that on the Katana 600 and 750, the fairing opening does push against the selector lever, so you have to do some small trimming for it to clear and turn freely.
This works for a GSX750F, however the on setting does not give the carb enough fuel to stay running, no matter how many psi of vacuum. When set to RES it gets a little more fuel. When set to Prime it gets plenty of fuel but the problem is that it could flood the engine. Keep this in mind when buying.