I've been using RAM mounts for GPS and Sat radio on my bikes for years. You can get good prices on them through Express Mounts which is a sister company to GPS City.
And even if it would work I would NEVER use any kind of suction mount on the shield of a bike. No matter how good of a connection you think you have it will vibrate off when you least expect it.
This is a pic of my Garmin mounted with a RAM mount. Nice and secure.