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 DIY Carburettor Filter Mod...

Issue: In dusty or sandy conditions the metering diaphragm can become contaminated with dirt. The dirt can enter through the breather hole at the rear of the carburettor. The hole allows the diaphragm to function properly during carb activity and the resultant ambient pressure changes.

If the hole was to become blocked, or the diaphragm heavily contaminated with dirt, the carb's performance would be affected.

Solution: The filter is designed to keep the diaphragm free of dirt and reduce the need of cleaning or replacement by protecting that opening - in a similar fashion as the air filter protects the engine. The filter does not require the carb to be removed for the install. This mod is based on an original concept and part developed by Team Chase.

The mod consists of cutting and grinding an aluminium channel, 15 x 10 x 1.5 or 1mm thick (1) to form the filter housing. A suitable channel can be found in most good hardware stores. The 10mm width will fit perfectly to meet the main body of the carb immediately below the diaphragm (5)

Cut a section of channel the same width of the carb body.

Depending on whether one is readily available, a spare carb, can be useful in serving as a template, rather than having to remove an already installed one.

Remove the metal bulb holder (3) by removing the 4 small cross head screws and use as a template to ensure the required two screw holes and curved section in the new filter housing are accurately aligned. A 22mm diameter circle template may be useful to mark the curved part.
Drill the holes and grind down the curve as necessary with your preferred tools.

Reduce one side of the channel (one of the15mm sides) to meet the main body of the carb. Cut out a section of the channel base to align with the cap headed manifold bolt which may otherwise clash (4)

Using a HPI outer foam filter element or similar, cut a small section that will fit neatly and squarely into the newly made housing (6). Ensure the foam filter is not too compressed. If desired, oil the filter in a similar manner to that used for oiling the air filter.