Your motorcycle’s air filter

Your motorcycle’s air filter

Your motorcycle’s air filter is one of the components subject to periodic maintenance, cleaning or replacing it.

Depending on the type of air filter used (viscous paper, oil impregnated foam, etc.) and the type of use you give to your bike (road, off-road) you will have to perform the maintenance tasks more or less frequently.

But we don’t want to argue about the sex of angels by discussing whether 7.500 miles is a short or long period to check your motorcycle’s air filter.

What we want to do is to explain why you should not replace the your motorcycle’s air filter by a high flow one, that is, one that lets more air through.

Why shouldn’t you replace your motorcycle’s air filter with a high flow one?

First reason not to replace the air filter

Air filters let “X” amount of air through. The motor actually draws the air contained in the air box through the filter surface.

Filtro original
An original filter of today offers the best performance with the original configuration of your bike.


If the filter on your bike is very dirty, the engine will suck in less air than it should (try breathing a big breath of air with two masks on top of each other or with a used sock in your mouth), but the injection system will “push” the same amount of fuel, so you will have a “rich” mixture. (Ideally an engine should have 13 parts of air by every part of gasoline).

If your motorcycle’s air filter is dirt, it will cause a series of symptoms on how your bike behaves and possible breakdowns in the medium to long term, such as the deterioration of your catalytic converter.

On the other hand, if you remove the your motorcycle’s air filter, the engine would suck in through …. of nothing.

Imagine now with your mouth open running in the summer through a swamp. Pure protein, so all the dust particles, dirt, insects, etc… would enter directly into your engine.

Consecuencias si quitas el filtro de aire de tu moto
Something like this can happen if you don’t change an air filter …..

This will cause premature wear of pistons, cylinders, rings, etc.. and as a direct consequence, a higher consumption of engine oil, lack of cylinder compression, oil pumping into the air filter box ….

But this was not the purpose of this post either.

Second reason not to replace the air filter

In the auxiliary industry, there are open type “racing” filters.

What does this mean?

Well, they are filters that “filter” less than the original ones, in order to let more air through “increasing” the engine performance.

Filtro de aire de alto caudal
High flow air filter. You can find two types: those that have a better filtering capacity but for street use and the competition ones, which filter less. Either way, if you increase the air volume, you have to increase the fuel volume.

Can I increase engine performance by introducing more air volume?

Yes and No.

Yes, if it comes together with a greater volume of fuel. Meaning reflashing your ECU, installing a Power Commander or cheating the fuel injection system by changing the water temperature sensor signal.

No if you simply replace the filter.

For this second reason, if you are not going to give more fuel to your engine, do not accelerate its internal wear simply by having one of these filters.

It will actually take power away from your engine, despite what’s advertised by the air filter manufacturer.

Hey, I’m not saying they are misleading advertising. I am saying that they DO give more power but only if accompanied by an increase in fuel delivery.

Although to be honest, this is not where we were going with this post either.

THE Reason

The reason for this post is another, very different one.

It turns out that recently my brother-in-law showed me a used bike he was looking at. He likes bikes “with presence” and is always looking for something with an open muffler.

I was surprised by how white the end of the muffler was.. I soon realized that it wasn’t just the muffler that had been changed: it was the entire exhaust line.

And on top of that, stickers from a well-known brand of racing air filters..

I told my brother-in-law to ask the seller if the ECU had been reflashed.

A few minutes later he received the answer: the control unit had not been touched at all.


So, to recap: By removing the complete original exhaust line, which has a catalytic converter (or several distributed throughout the line) and a labyrinth muffler and installing a fully open exhaust system, the exhaust gas waves are modified, LEANING the gasoline-air mixture (higher proportion of air than gasoline).

Colector full line
Full line collector. Be careful, these things are loaded by the devil if you don’t know what you’re doing!

If, in addition, an open air filter is installed, letting in even more air, an already lean mixture is leaned again.

This will cause an excessive heating of the engine and its components, causing several breakdowns, lack of performance (if it does not “have” gasoline, it will not give much power) and that someone, maybe you, will loose the bike.

Therefore, whenever you are going to replace a component by a “competition” one, get information (if the seller’s explanation doesn’t help you, ask us through our Whatsapp or e-mail) if it’s suitable for the use you are going to give to your bike.

We all want a more powerful engine, but the increase in power is usually expensive and ALWAYS goes against the durability and reliability of your engine components and the lifetime, in general, of your bike.

So, in short, replace your motorcycle’s air filter, but for one just like your stock one if you are keeping your bike as it is from brand new.

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