When using one you'll be holding the throttle wide open. On most bikes you'll also be holding in the clutch lever so the starter motor will turn over. This means you have no hands free.
As long as the push-on type seals it'll work fine, but assuming a 10mm plug hole and 200psig, you're looking at about 30lb force trying to push it out. I'd be tempted to find a 3rd hand to hold it in place.
I've never had any problems with the screw in ones, but they're made for car size plug holes so you need to buy adaptors to fit which ever plug size your bike has.
arrrf.
