I have checked online for how fast certain sport quads are but every website says something different
I am wondering how fast a stock quadzilla 500, banshee and blaster will go

 

I have heard the stock quadzilla 500 will top out around 95 mph and modded easily 100+
Banshee I think somewhere around 80 or so not 100% sure but I'm sure someone else will share their thoughts!
Hope this helps!

 

I highly doubt that.
The 500 was the same motor that was already in the RM500 "open class" motocross and it was rated at 50hp. That much lighter bike would need some major sprocket changes to get to 100 mph so can you imagine the motor in a heavy ATV?

Here is the true hp, LT 500 Quadzilla Horse POWER!!!!!! about 50hp and 42hp to the ground.

My 4 cylinder 74hp Kawasaki kz750 street bike only did 110mph on a flat paved freeway.

 

See what I mean? Everyone says something different! One website said a stock quadzilla will do 130 mph and another said 75

 

I had my 100hp four cylinder Yamaha 1100 Midnight Special street bike up to 130mph with nothing left to go, on a 4 lane free way.
It sure would of look funny with a ATV (Any ATV) hanging with me that day.

My 2012 Ski-doo 800R E-tec is rated at 165hp and only does 120mph on hard packed frozen lakes.

 

I think realistically the quadzilla would hit 80 mph in stock form and you could probably gear it to run 85, maybe 90 if the conditions are perfect. 50 HP is plenty to get a 400+ pound vehicle over 100 mph but the gear ratios throughout the transmission is what limits an ATVs top speed in favor of low end pulling power. The larger/more powerful the engine, the higher a manufacturer can gear it without losing power down low.

 

The max is usually around 75 give or take on the 450 and above crowd(Plus the 250 2 strokes.) I remember an old dirtwheels article from back in the day. They put a radar gun to the task and we're getting mid 70s for both the zilla and banshee. I think with some gearing changes and a few mods the zilla did get over 100mph eventually.

Most of the bigger sport quads are held back by gearing and even aerodynamics somewhat on the top end.

Here is a link to a banshee article, but I am pretty sure there is a zilla one too.Yamaha banshee vs radar gun dirtwheels article