Twin Air Dust Cover

What it is

The Twin Air Dust Cover is a coarse foam pre-filter that sits atop your standard air filter to give it more time between cleanings, or help the air filter survive harsh racing conditions. It can be installed dry or with coatings of anything from a very light oil to true air filter oil, depending on your needs.

How it works

• Simple to install over main filter.
• Does an amazing job in dusty conditions, hence the name.
• It will save you money in air filter oil.

For the most part, installing and using the pre-filter is straight forward. You just place the cover over the standard air filter and install it all as one unit. It does not wrap around the standard filter, therefore it does not interfere with the critical sealing lip of the filter. In tight fits, like a Honda CRF 450X, keeping the pre-filter in place can be tricky and require some extra care in placement. But on bikes like KTMs with an easy and open access air box it is simple.

In use the pre-filter was actually amazing, most notably in thick dust or silty conditions. In our estimation it quadrupled the time you could ride between cleanings, that with the pre-filter coated with a light, less sticky oil like WD-40. We tried it dry, with a light oil, with non-oil air filter oils and with proper air filter oil. Our best results were with the light oil and non-oil filter oil as they, being less sticky allowed the dust cover to do the best work. It was like a fair amount of the dust gets bounced off the pre-filter and then falls away, never getting to the main air filter.

Riding with little dust, like a prepped track or after a rain, the pre-filter did not seem to slow the speed at which the main air filter became dirty from heavier dirt. But in wet or muddy conditions it again provided a benefit of better deflection of water, meaning the water fell and drained off the coarse outer layer better than it did for just the denser main filter. None of the oils we put on the filter affected the glue and the dust cover was like new, just stained a bit after over a year of service.

The $18.95 price is a fair call for something that will pay for itself in air filter oil very quickly, not to mention the pain of cleaning the air filter in the first place. Especially in the dust, this is a must-have.

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