Most of us have been there early in our riding days. We are getting ready for our first 125cc motorcycle or scooter, and that ever so elusive question floats into our heads, just how fast can this two-wheeled beast go?
The short answer is that the top speed of a 125cc, on average, is somewhere between 65mph and 80mph.
However, to answer the question properly, we need to look at the factors that affect how fast a motorcycle can go and then we will give a short round-up of some of the fastest 125s on the market.
Let’s start by looking at the legal restrictions that 125cc motorcycles and scooters have to adhere to.
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Legal restrictions
In the UK, there are power output restrictions for those riding on an A1 licence or those who are riding having gained a CBT certificate.
If you have an A2 or A licence, there are no restrictions on the power output for the 125cc of your choice.
So for those with a CBT or A1 licence, this is what you need to know:
You can ride a bike up to 125cc with engine power that does not exceed 11kw (15 horsepower) and the maximum power to weight ratio of 0.1kw per kg.
As a result of these restrictions, most new 125’s meet this power output or come in below it.
Two-strokes
At one time, mainly throughout the 1980s, two-stroke small capacity bikes were all the rage, and they were fast!
The Aprilia RS125, for example, was the king of the race track and could quite easily see speeds of over 100mph.
However, today’s RS125 is a shadow of its former self, opting for a four-stroke Euro 5 engine and complying with the legal power output of a 125cc. It still looks pretty special, though.
It is essential to understand that just because a bike is advertised as a 125cc doesn’t mean it meets the legal requirements of a 125cc for learners or A1 licence holders.
This is mainly applicable to older two-strokes, so that will give you a good idea as to whether the bike is legal to ride or not.
For example, the Gilera Crono in the 90s had a max power output of over 29 horsepower and a top speed of 105mph.
Many offerings from Yamaha, Suzuki etc., could also be de-restricted to unleash more power from the two-stroke motors.
Therefore when looking for a 125cc, make sure that it has a maximum power output of 11kw/15hp.
Anything bigger, and you will need to do your A2/A licence to ride the motorcycle legally.
What factors affect the speed of a 125cc?
Two key factors affect the speed of a 125cc:
- Aerodynamics
- Weight
Aerodynamics and Weight
If a bike can cut through the air and experience little wind resistance, it will move faster; ironically, with a 125cc, that doesn’t necessarily mean it needs to have the best cutting edge fairing.
In the case of the MT-125 and R125, the former being a naked motorcycle and the latter fully-faired, it is the MT-125 that actually has a higher top speed of 80mph.
A significant factor in this is that the MT is 2kg lighter than the R125.
When it comes to a 125cc, any weight reduction is positive and can make all the difference in speed.
However, this can be problematic if the bike is too lightweight and not aerodynamic enough. Facing a headwind on a 125cc can be a pretty terrible experience slowing you right down and blowing you all over the road.
Therefore manufacturers have to walk the delicate balance of enough bodywork to do its job against the wind but not too much that the bike becomes too heavy for the engine’s power to cope with.
125cc scooters are pretty good at hitting higher top speeds. This may be down to how the bikes are designed to cut through the air and be aerodynamic.
The top two fastest scooters are actually both significantly heavier than the MT-125 but have the same top speed.
Fastest 125cc Motorcycles
| Motorcycle Name | Top Speed |
|---|---|
| Yamaha MT-125 | 80mph |
| KTM Duke 125 | 77mph |
| Yamaha R125 | 75mph |
| Honda CB125R | 74mph |
| Kawasaki Ninja 125 | 74mph |
| Suzuki GSX-R125 | 72mph |
| Aprilia RS125 | 70mph |
Read an in-depth review of the Fastest 125cc motorcycles
Fastest 125cc Scooters
| Scooter Name | Top Speed |
|---|---|
| Honda Forza 125 | 80mph |
| Yamaha XMAX 125 | 80mph |
| Italjet Dragster | 75mph |
| Piaggio Medley S | 70mph |
| Honda PCX125 | 67mph |
| Peugeot Django 125 | 65mph |
| Vespa GTS Super Sport | 65mph |
Read an in-depth review of the Fastest 125cc Scooters
Final Thoughts
Great things come in small packages, and 125cc bikes epitomise that idea.
They are a blast to ride, and some of them are pretty fast; be sure if you are restricted licence wise, to check the power output of your chosen 125cc to make sure it complies with the legal restrictions.