.

Correspondingly, is 250cc motorcycle safe on highway?

So, unless the newer 250cc bikes have substantially poorer handling, brakes, and horsepower than a 250 from 20 years ago (and they don't- just the opposite), the answer is yes- modern 250cc motorcycles are absolutely appropriate for freeway commuting.

Secondly, how fast does a 250cc Kawasaki Ninja go? Yes, the ninja 250 will do 80 pretty much all day long at 9k rpms (redlines at 14k). Some folks swap out the front sprocket to 15 tooth to get the rpms downwhich may be good if you're doing lots of highway miles. - Redline on the '06 and later 250R is 13000. At an indicated 60 mph, I run 7500 RPM.

Simply so, how fast does a 500cc motorcycle go?

100 mph

Can a 250cc motorcycle make long trips?

Any trip is composed of the times that you spend sitting on your motorcycle and the times that you spend taking breaks. If you can ride 50 miles in one sitting, then you're already on your way to becoming a long distance rider. Ride for 50 miles, take a 20 minute break. Or 300 miles.