Saito 91 and 100 air filter

My first Saito's, is there an air filter made to go over the carb?


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No, but wise men make one out of window screen cloth covered with old stocking material. Use zip ties to hold the assembly together and on the venturi stack.

I took the screen wire and wrapped it around the knob on my drill press to get the shape since I wanted lots of surface area to avoid choking the engine. This got zip tied to the venturi stack. THEN I got an old pair of stockings and put a chunk over the wire and zip tied it to the venturi stack. Keeps the dirt out and does not appear to starve the engine for air.

YMMV - good luck,

Jim Branaum AMA 1428

Six_O'clock_High Target

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As you know, there is no "stack" on the Saito .91 or .100 carburetor face. The Saito carburator has a flat face with just the two fore and aft rails at the edges that extending from the face about .025". The rails are a hold-over from a design that used a sliding choke. There is nothing to fasten a filter over on the carburetor. However, you can fabricate a very secure filter from 304 stainless steel screen and use the two carburetor mounting screws to hold it in place.

You can obtain fine mesh filter screen from "Small Parts, Inc."

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(1-800-220-4242). Call them for their really neat catalog. The catalog has all sorts of hardware, tubing, mall gears, metric bolts, etc.

If you have a hobby shop that stocks the round flexible tube and wire screen filter assemblies for 2-cycles, you can scrap the tube part and just use the filter screen material from the assembly in the "Quick and Easy" method.

I have a Saito .91 that I fabricated a filter for using the 100 x 100 304 SS mesh. The openings in this size mesh is about 0.006". The ONLY reason I went to the trouble is because I was flying from a field with lots of sand blowing around.

Here are two fabrication sequences; one very secure method, and one easy/quick method.

Very Secure Method:

1) Remove the carburetor from the engine.

2) Close the throttle barrel and pack the throat with tissue.

3) Use a file to remove the two rails from the face of the carburetor so the face of the carburetor is flat.

4) Cut two 3" long pieces of square or rectangular maple stock (or other hardwood) to the front to rear width as the face of the Saito carburetor. The carburetor face is about 0.57" There is enough screen in even the least expensive stock size that you can experiment a little to get a perfect fit. The two pieces of hardwood form bending jig for the ss filter material.

5) Place a 2" x 1.5" piece of the filter screen centered on the 0.57" face of one piece of the hardwood so that the 2" dimension is along the same long axis as the piece of hardwood. Put the other piece of hardwood over the screen so you form a sandwich of wood-screen-wood. Make sure the two pieces of wood are aligned with each other and then use two small clamps at the ends of the two pieces of wood to clamp the assembly tightly together.

6) Use a small tack hammer to bend and form the edges of the screen material down the side of the "bottom" piece of hardwood. Once you have the "U" shape started, you can place the assembly on a hard surface and hammer the edges of the screen into almost a 90 degree angle at the bends. The exercise is to form the screen into a "U" channel with the bottom face of the "U" at a size that just fits over the carburetor face. And, the "skirts" of the "U" are long enough to reach up to the bottom of the carburetor throttle barrel. This gives you enough material in the skirt so that you can drill or punch holes to pass the two carburetor attachment screws.

7) Remove the screen from the clamped bending jig and trim the screen "U" assembly to be just a little wider that the left to right width of the carburetor face.

8) Place the "U" screen assembly over the face of the carburetor and mark the carburetor attachment screw locations on the skirt of the "U".

9) Place the "U" screen back into the hardwood clamp assembly and then drill the holes in the screen jut a little bigger in diameter than the carburetor mounting screws. If you have a drill press, you can use a third piece of wood under the assembly and drill straight through both sides at once. If you don't have a drill press, then drill just through the screen from each side.

10) Here is a slightly tricky bit: Measure the thickness of the screen. Use a file to file away that amount of material from the face of the carburetor mounting boss on the engine's back-plate. You must keep the face of the mounting boss "flat" as you remove the material. Removing the material from the mounting boss keeps the alignment of the carburetor and intake manifold the same when you sandwich the screen's skirt between the mounting boss and the side of the carburetor.

11) Clean away any filings from the case and the carburetor. Remove the tissue from the carburetor throat. Make sure there are no filings in the carburetor.

12) Clean the face and sides of the carburetor with Acetone - don't get any Acetone on the plastic throttle arm.

13) Apply a Very thin bead of automotive (BLUE) Silicone gasket around the edges of the face of the carburetor.

14) Place the screen assembly over the face of the carburetor and align the screw holes.

15) Re-mount the carburetor (now with the filter assembly in place) to the engine.

16) Permit the silicone to cure.

Easy and Quick Method:

1) Cut a disk of filter material sized so that it is a perfect fit with the outer, round "step" in the face of the carburetor. You place the silicone bead around that step. OR, trim the round filter from a ".60" size pre-made assembly. Remove the filter material from the mounting ring because it adds to much suspended mass.

2) Clean the carburetor face and a filter material very well with first soap and water and then Acetone and then MEK. Wear clean gloves to handle the filter material and carburetor so you don't get skin oils on the assembly after cleaning.

3) Apply a small bead of the automotive gasket silicone around the step in the face of the carburetor throat. You will need more of the silicone on the right and left edges of the face because of the rails on the front and rear face of the carburetor. - Unless, of course, you file away the surplus rails.

4) Lightly press the diske of screen into the bead of silicone gasket material. Let the silicone cure for 24 hours.

The face of the carburetor and the screen must be very clean and free of ANY contamination for the stuff to stick. There are other adhesives (Hysol epoxy) that will stick solidly to both the aluminum and the screen, but that makes the assembly TOO permanent.

I used the quick and easy method first in a cowled installation. It stayed in place for about ten flights.


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