How to make my 125cc scooter faster?

Do you have a 125cc scooter and don't know how to get more performance out of it? In this article we are going to explain you how to increase the power of your 125cc scooter that you want so much on your 4-stroke scooter.

First of all, you must know the legal framework and regulations of your country so that it does not affect your emissions or limit your driving license. In the case of the Spanish territory, you should know that a person with a B license (3 years old) or with an A1 license is limited to drive a motorcycle up to 125cc and 11kW, which translated to horsepower is 15hp, with a weight/power ratio of 0.1 kW/kg.

3 Ways to increase the power of your 125cc scooter

There are different ways to improve the performance of a 125cc 4-stroke motorcycle. The most common would be to increase the cubic capacity of the bike by changing the cylinder, piston and cylinder head, but, besides being a very expensive modification, we would be outside the law.

Therefore, we will stick to those modifications that comply with current regulations and do not pose a problem for you, your insurer or other road users.

Exhaust pipe replacement

It is one of the most common modifications that you can find, and also one of the simplest. It is true that, in terms of performance, a 4-stroke scooter will gain between 1hp or 2hp.

This modification is more often done for aesthetics and sound than for performance, but if you are looking to increase a little the performance of the bike without modifying anything mechanically and also give another look to your scooter, this is your option.

We recommend that before buying a new exhaust for your motorcycle, you take into consideration the emissions and road regulations, as our new exhaust must be homologated.


Performance exhaust pipe to boost the power of a 125cc scooter

Change the variator of your motorcycle

The variator is the part that connects the power generated by our engine with the transmission system. It is at this point where most scooters waste the most power, as it does not usually take advantage of all the torque generated by the engine of our scooter.

It is one of the most recommended modifications if you are looking to take advantage of all the power generated by your engine, since we will be able to send it to our rear wheel through the belt.

To emphasize that with a performance variator we are not going to increase the horsepower of the bike, but we will modify the power curve and get all the horses of the scooter to reach our wheel. Therefore, we can say that we will gain about 2hp (depending on the model) complying with all regulations since we are not modifying the power of the engine.

One of the advantages of installing a performance variator on our scooter is that we can modify the performance according to our needs. That is, if we do more urban stretches where what we want is more acceleration, we can equip the variator with lower weights so that it revs more and gives us more power at low speeds. If, on the other hand, we drive more on highways or interurban roads, we can install higher weights in our variator to achieve more top speed.

It is always recommended to play with 1 gram at most in the weights of our variator so that it does not change drastically the operation of our motorcycle.

JCosta speed variator to increase the power of a 125cc scooter

Change the electronics of the motorcycle

If what you want is to increase the power of the bike to your liking and directly modify the engine map of our scooter and its injection, this is your modification. We could say that it is the equivalent of changing the carburetor, but for an injection motorcycle.

We must be very careful since it is possible that, by modifying the injection and the engine map, the emissions generated by the engine are higher and we do not comply with environmental regulations. In addition, it can compromise the integrity of our engine for a use for which it was not manufactured.


We recommend that you carefully evaluate your case and needs before making any modifications and, above all, that you purchase high quality components with European homologation.

In this way, we ensure that, even if we increase the power of our 125cc 4-stroke scooter, we will not have reliability problems and our bike will last longer.

We hope this article has been of interest to you and that you have been able to learn how to increase the power of your 125cc motorcycle. 

At JCosta we are specialists in performance elements for scooters always ensuring a correct functioning and the integrity of your vehicle. If you are looking to enhance your scooter enter our store and find all the components of the highest quality for your model at the best price.

Types of motorcycle exhaust pipes
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