Check that your ignition switch actually switches off. Also hit the kill switch button to see if it actually kills the motor when running. The killswitch is not the best quality, and maybe there's power on all the time.
Otherwise you could have a power-drain somewhere, and if the bike's still under warranty, let Honda check it out.
The throttle setting... when "snapping" the throttle open, it might be that the carb is either running too lean, resulting in the motor getting too much air, and not enough fuel. I find that when the motor is not at operation temperature, this happens as well... (engine splutters).... works fine once the bike's been run for a while (ie hot engine.) Also don't forget that you have a direct slide on the carburettor, and by whacking the accelerator open from zero to max in a split-second the air-fuel mixture changes too quickly for the engine to compensate immediately. Open the throttle a bit more slowly....
