Is No Air Filter Better Than A Dirty One?

Air filter in a motorcycle

Which is worse – no air filter or a dirty air filter?

While a clogged air filter is always looked at as a bad thing and advised to be addressed, no air filter is something that is rarely touched upon.

So, is no air filter better than a dirty air filter? A dirty or a clogged air filter is any day better than no air filter. Running without the air filter can cause long-lasting damage to the engine whereas a dirty air filter will result in low mileage for the time being.

The major impact of running a motorcycle without the air filter will obviously be on the engine.

The engine will overheat in no time. Dirt gets accumulated to form deposits. Piston and piston rings will be harmed. Inner cylinder walls of the combustion chamber will be damaged to the extent that they may need re-boring to function well.

Such can be the immense negative impact of running without an air filter in your motorcycle. To discuss these in detail, let’s dig in.

Is it better to have a dirty air filter or no air filter?

Dirty air filters are better than no air filter any day.

While a dirty air filter restricts the air entry into the engine and will cause performance problems, using no air filters can be even worse.

Having no air filter while driving your motorcycle can result in air dust, dirt, and other contaminants entering the engine. This, in overtime, will result in slug formation and deposits – thereby harming the engine components.

Sure, more air will enter the engine if there is no air filter at all.

But, more air – that too unfiltered – is no way a good thing.

First, too much air into the engine mean a lean air fuel mixture. And if the fuel mixture is lean, the engine is going to overheat and perform poorly.

Second, the air is unfiltered. Such unfiltered air entering the engine will be harmful and damaging to the engine components. The dirt and dust particles will start accumulating and form deposits. Over time, the engine components get so contaminated that replacing them will become the only option.

What happens if you run a motorcycle without an air filter?

While you can run a motorcycle without an air filter technically, it is advised not to.

One should not ride a motorcycle without an air filter. While you might think a clogged filter blocking air entry into the engine is solved by removing the air filter. This approach is seriously flawed because while you have fixed the air entry issue, there is one more created in the form of unfiltered air.

The air entering the engine when there is no air filter is completely unfiltered one.

This air contains all the dirt, dust, and many other contaminant forms. When the air enters the engine, so do these contaminants.

These contaminants will start depositing and over time, will harm the functioning of the engine components.

In short, two things are going to happen if you run a motorcycle without an air filter:

  • The engine will run on lean mixture
  • Dirt particles in the air will start accumulating in the engine

Both are harmful to the engine performance and longevity. Running on lean fuel mixture will overheat the engine. Dirt accumulation will damage the engine components.

As for the effects of such accumulation, they are discussed in the next few sections.

Effects of no air filter

The major effects of running an engine without an air filter include:

  1. Engine overheating: The engine will run on lean mixture since the air intake will be too high. No air filter translates to no restriction on air entry. In no time, the engine will start to overheat.
  2. Dirt accumulation: Since the air entering the engine will be completely unfiltered, the air will bring all the dust, dirt, and other contaminants along with it. This dirt will slowly start accumulating in the engine.
  3. Poor engine performance: A combined effect of dirt accumulation and overheating. The engine will start to under-perform and if unchecked, the performance drop will be too much for the vehicle.
  4. Engine components getting damaged: Over time, the sludge and deposit formation by the contaminants will take a toll – resulting in the engine components getting damaged. Mainly piston and inner cylinder walls.
  5. Damaged piston and piston rings: The contaminants entering the engine will harm the piston and the piston rings the most. Eventually, you might have to replace them for better engine performance.
  6. Inner cylinder walls requiring re-boring: Another main component getting damaged will be the engine cylinder itself. The inner cylinder walls will be so problematic, that re-boring the cylinder will be the only option left.

Effects of a clogged air filter

Now, instead of no filter what if you continue to run the motorcycle with a clogged air filter? Will it be as bad as no air filter?

A clogged air filter is not as bad as running without an air filter. But, there are still many negative effects.

That’s why you got to replace or clean the air filter regularly.

As for the clogged air filter, the air entry into the engine is restricted. the dust layer on the filter material does not allow enough air to get sucked in.

This insufficient air into the engine results in a rich fuel mixture getting burnt in the combustion chamber. The impact will be visible in decreased motorcycle mileage and exhaust backfiring.

How to know if your motorcycle needs a new air filter

Now, how do you know if you need to change or clean the air filter? While a detailed post on when to change the air filter is here, the highlights are included below.

  • The air filter is blackened: If the air filter is clogged to the point that the filter material is blackened, it is time for you to replace the air filter.
  • Too much exhaust backfiring: Exhaust backfiring happens when there is un-burnt fuel in the exhaust, which in turn is possible only when the engine is seeing fuel-rich mixture and not enough air. So, time to check and replace the air filter pal!
  • Decreased mileage: Since there is not sufficient air entering the engine, lots of fuel get unburnt. As a result, you will start noticing the mileage getting lower and lower.
  • Power lags: Power lag happens when at higher speeds your motorcycle won’t accelerate despite throttling up the motorcycle. If you are facing a power lag, then a clogged air filter – which is preventing sufficient entry of air – is the main culprit.

Air filter change interval in motorcycles

On average, a motorcycle air filter should be changed for every 12,000 miles of distance traveled.

In addition, the air filter needs to be frequently examined, whether they are clogged or not, every 3 months or every service cycle. Make sure to ask your service shop to check the air filters regularly.

For a more detailed view, here is our post on change interval for air filters.