What are the advantages and disadvantages of installing high performance air filters (K&N,Green cotton,etc.) over original filter?

What are the changes/working occur internally?

3 Answers 3


Normally the idea is to get more air into the engine using a less restrictive air filter. As an engine is basically an air pump, getting more oxygen and more fuel into the engine usually equals a bigger bang and thus hopefully more power.

That said, in order to get a meaningful improvement using a performance air filter, the main restriction needs to be the air filter in the inlet tract and the head and exhaust need to be able to cope with the increased airflow. If that's not the case you won't see any performance improvement. You should also tweak the mixture to deal with the additional airflow unless your bike has fuel injection with a lambda sensor and basically can enrich the mixture automatically. If you don't adjust the mixture and you get a meaningful increase in airflow, chances are that your engine will run lean at the top end and the bigger bang might be a piston's bid for freedom.

An advantage that doesn't have much to do with performance is that these filters are often washable so instead of throwing the paper filter away and buying a new one, you can clean (and usually re-oil) the filter. So in the long run it might work out cheaper.

  • I second that washable advantage. I use K&R on my Subaru. It has 130,000 miles now with 3 washes and re-oiling and still smells new.
    – WRayX
    Oct 19, 2012 at 3:53

depends on if you have carburetors or fuel injection

If you have a carburetor


  • You will make the bike have a lean condition

  • Backfire on deceleration

  • More oxygen will create more engine heat and this will cause additional wear on components

  • You could burn your exhaust valves


  • You could buy a jet kit and pipe to go with it and get a few extra HP out the bike.

if you have fuel injection


  • A little more power

  • Your FI will automatically adjust your mixture

  • Air flow improvement

  • Possible better particulate removal


  • I can't think of any

Typically the main difference between a 'normal' stock filter over a high performance one is airflow.

They are designed to retain the filtering capability, but have superior airflow (design, materials, shape of filter internals etc) to allow more oxygen to the engine, which means you can get superior burn and greater output power.

So pros:

  • Greater airflow and improved filtering of particulates


  • Cost
  • I read a comprehensive study on filters awhile back. I'll do a quick recap and hopefully I can find that link again... Filtering is a mixed bag with the standard cotton/oil filters out there. Initially, when completely clean, they do not filter as well as a stock filter. However, they filter better as they accumulate some dirt. Feb 17, 2012 at 14:08

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