In the late 80s, early 90s, a co-worker gave me a running XS650, the one with the Akront alloy wheels. Doing as per my usual MO, I put a 19 in Dirt Track tire on the front, and a K81 on the rear, some flattrack handle bars (#10 Flanders bend, if I recall correctly), and I rode that sucker to work, every day for 2 years. There was even a road jump/railroad crossing, I hit that sucker every day at about 90, and caught maybe 5 or 6 inches of air, probably 15 feet past the crossing, great fun. One day, right after the road jump, the engine locked up at about 90. Being an old 2 stroke guy, I was pretty quick on pulling the clutch in and coasting to a stop. I started looking at it, and there was a crack, from the exhaust flange, all the way down the cylinder, and into the cases. Whoa. I trucked it home, took the carbs off, and there was a piece of cylinder liner in the carb. Turns out that it dropped a cam chain, at probably 6500rpm or so. That was it for that bike, gave it away for parts. It was fun to ride though. There was a dirt oval out in the farm fields on the way to work, and after work, I'd pop off a few laps around it. Just for kicks.
KTM 950 SM, my main squeeze now.
And now, an XR75, more motorcycle than many here can handle.
All my bikes have 13/71 gearing. Top speed, 8mph.