914 Air filter

Spread a thin layer of RTV silicone on the filter and let it cure before installing.

You can check whether K&N RC-9380 fits your engine installation (fits under cowling etc.).

I have determined that K&N RU0600 air filter fits a 914 turbo inlet properly.

The turbo inlet measures 2.35” (59.69mm). 

Rotax specifies P/N 825750.  The illustrated parts manual shows filter ID is 2.44” (62mm), filter media height is 3.94” (100mm) and media diameter is 3.54” (90mm).  I purchased this filter and received a K&N RU0800 filter, with the Rotax part number on the box.  Indeed K&N website confirms the above dimensions.

The inlet diameter is too large. If you tighten the clamp enough to secure the filter, the filter is forced off the turbo.

K&N states “All filters are constructed with ultra-strong molded pliable rubber flanges which absorb vibration and allow for secure attachment and can also be stretched for up to 1/16 of an inch (1.5mm) to fit in-between sizes.” 

RU0600 is listed with ID 2.25” (57mm).  Media height and diameter are the same as RU0800.

I purchased RU0600 from a local parts store with hopes that it would stretch and fit. It fits the 914 turbo perfectly! The clamp holds it in place without distortion and does not try to force the filter off the turbo.

I have advised Leading Edge Airfoils of my finding and also filed a report with Rotax.

RU1700 appears to have the same dimension with a 20 deg offset that some need to fit their aircraft.