Come on now, don't get all butt hurt about a little teasing. In all actuallity, it just isn't feasible to have something that runs out over 3 digits. #1) ATV tires are not rated for that speed nor are they balanced which should be something you think about before even attempting those speeds. 2) As John said, it is nothing more than a gearbox with you max engine RPM being the begining factor (regardless of stroke, bore, HP or TQ) followed by the drive sprocket, driven sprocket and tire type and size (I specify type because some tires actually grow taller at higher speeds).
Now, in order to get there you are gonna have to gear it pretty tall and to pull that tall gearing you're gonna need a big motor,. Drag bikes make a lot of power at higher RPMs and are geared such that they run out of gear at what hopefully is the end of the track because there is no need for more gear. But it isn't about top speed, it's more about getting off the line and, say a 60ft time, on a 300 ft track.
Sure, we can all gear up and go faster but if you can't get the bike rolling to start with it is fairly useless.
We have all read so many posts about triple digit bikes, boost bottles, ported heads, etc, that we have a tendancy to flame anyone that brings them up. It doesn't mean we don't or wouldn''t like you, it just means if the question is rediculous at the core, you may get some shit for it. That's all
SP