So, how fast is a 125cc Motorcycle?

I am sure you have seen people on the forums stating they have had 120mph plus out of their 125cc bike, but in reality, this is not an accurate figure, for a number of reasons..

Speedos usually read about 10% over, so that takes 12mph of that speed.

Then there is rounding up or exaggeration, so you are looking at a maximum speed of about 95 – 105 mph true speed, which is highly possible on some bikes.

If you have a Mito or an Aprilia RS, you can realistically get a ton, if your bike is de-restricted.  My RS will do an indicated 105 – 110, so that could be a true 100mph.  My old TZR 125, fully derestricted, done an indicated 95.  If your bike is a 4 Stroke 125cc then your speed, flat out, will be about 65 - 85 mph.

You can increase your bikes top speed, through tuning, but also through gearing.  Check out the 2-Stroke Engine Tuning section!

However, the main strength of a 125cc motorbike is not the crappy top speed, but its ability to go round corners very very quickly.  A half decent 125cc 2 stroke, with a half decent rider, will batter most if not all big sports bikes along B roads and twisty A roads.