I turn my petcock off everytime I get off the bike. Its a good insurance policy against a leaking float valve which would result in gasoline in the engine in quantities that its not designed for. Ideally if your carb is in good condition, leaving the petcock on will not hurt anything, but if you have a fuel leak or ??, its an added risk factor to leave it on. I also have a hot water heater (with a pilot) in my garage, so I really avoid gasoline risks in there. Its just a habit thats easy to incorporate into the fireup and shutdown procedures. Tom
I turn it off every time I shut down if the bike will sit overnight or longer and for sure any time the bike is being transported. I agree with the above comment about leaking gasoline in the garage--bad thing that's not worth the risk.