Loss of power with air filter installed

I have a 503 DCDI running on a pusher GULL with three blade prop. Similar problem; (a) air filters off completely runs as it has been before a month ago (b) air filters on I get the stumble and failure to "spin up" smoothly. A month ago this was working fine: advance throttle smoothly and power comes up smoothly into the lift off speed. ( I have tried several different filters and each one has similar but not exact responses). Was this above problem ever nailed down?

meannik503

Tommy

You might want to try cleaning and re-oiling your filters. There's a Rotax Minute video on this site that warns against over-oiling them.

Tom

   I had just this happen to me last Spring on my Challenger.  It was very repeatable, where I could take off at full power, do one circuit of the patch to an intended touch and go, but when I advanced the throttle, it would bog down at about 3500 - 4000 rpm.  I tried different jets and moving the clips and other stuff to no avail.  Finally, I tried once around the pattern without an air filter.  Voila!  It ran just fine.  I replaced the air filter with another that I had cleaned and oiled, but the problem came back!  One more time, (after some online research) with a clean, un-oiled air filter.  It behaved itself just fine after that, and the plane has run fine since!

   Try it with a new clean air filter, with no oil misted on it.  The 2-strokes puff mixture back from the carbs and wet the filters, which you can see after running as the filter turns blue from the mixture.

Gerry Visel