Join Date: Aug 2009
Location: Washington, the state
There seems to be mixed results with K&N air filters depending on the vehicle. Some report no problems after many miles. Others report dirt in the downstream side of the air box or high silicon in the oil lab test (a sign of dirt passing the piston rings). K&N air filters seem to be OK in stroms. I used a K&N in my Volvo and had dust in the clean side of the air box. Don't expect any benefit from any of these aftermarket so-called high performance air filters. If there is any benefit, it only occurs at wide open throttle and high rpm, and there is little evidence that air flow is improved. One excellent test of Chev diesel engine air filters (Spicer) showed that the OEM filter both allowed more air flow and cleaned the air better than a K&N--but that's not a strom.
Whatever air filter you choose, be sure it has a good gasket. The earlier stroms required re-use of the gasket, but many were tossed out in error. Later stroms came with the same filter plus a new gasket in the same box. K&N has a built in gasket on the filter assembly.
Hiflo makes an OEM-type air filter that is similar to the stock filter, and a bit cheaper. They have two catalog listings, one for older bikes that comes without a gasket, and the same filter with a gasket for $4 more that is listed for newer bikes.
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