Yep, those little bastards are fast.
My first bike was a Yamaha GTMX80, then I also had an XR75. Then right to a YZ125.
Back to the minis though, one of my favorite lines from Dirt Bike magazine was on a test of the new MX 60's of that year. The testers were blown away by the performance and said "Without exception, anyone small enough to fit on this bike is way too young for this much power."