If you're serious, and you're talking about the Brison 2.4,
while I can't find anything on the net, it appears
it would be trivial to fit a filter to it.

You could make a simple one of thin sheet aluminum
with a gasket on one side, and the filter media glued
to the other. Or, K&N makes all sizes of filters, down to
5/16 opening (.40 size) and an inch or so long.
Again, if you're handy at all, it would be trivial to manufacture
a mounting plate for your carb, and a short inlet for the filter.
(Don't know how much room you have. May have to play with routing)

I'm truly amazed that the manufacturers don't offer filters
for their engines. Heck, even a weedwhacker has a filter,
and it spends most of its life much farther away from the
grass/dirt than your airplane does on the taxi out, and takeoff
(And that's without a big fan helping to stir stuff up, too.)