New Pilot prefilter by hoser..
Another Prefilter upgrade, I want to eliminate the Prefilter box and switch to K&N filters
so I can eliminate the leakage I have been getting around the foam panel filter without
modifying the filter box and making it over complicated also using the K&N as a Prefilter
I can wash the filters wile on the road .

Using some 2" muffler tubing and a strap of metal I fashioned a filter mounting bracket.

Modifying the lid to the air box is pretty simple using a hole saw and another piece of 2"
muffler tubing, this picture gives you a good idea where to locate the second hole.

A cable operated butterfly could be installed in the second opening or in a 3rd opening so one could 
adjust his jetting setting at the drivers seat, I usually put a piece of duct tape on my frame so I have 
something to temporarily cover one or part of one of my openings on cold days  this allows me to 
change my jetting without having to change jets in the carb.

They make paint for plastic now you can get in cans, I haven't tried it but if you wanted to spiff 
your air box lid up you could try it.

Once you drill the hole with a hole saw you slowly easily bend over about 1/4" of the 
end of the muffler tubing then slide it up through the bottom of the new hole pop rivet
and then seal with silicone caulk.

New filter mounting bracket for 2004

Pre Filter New Design by hoser
Here is my second design and it is working much better than I had anticipated it would with 
the dry conditions of the Ocala forest their was plenty of dust and great testing conditions for 
air filters.

I decided to add some nylon stocking's over my K&N pre filters for the Florida ride (12-15-01)
after the pleats pretty much get full of dirt and mud at the Land Between The Lakes 
ride earlier this fall, I picked the nylons over the pre chargers to keep the cost low, 1.97 
for stockings that will make 8 disposable covers or 10.00 each for pre chargers that you 
need to wash when you service the filters.

As you can see the forward side of the filters gets much dirtier that the back side.

Here is what my main filter looked like after almost 3 days of eating dust near the Big Scrub
camp grounds, the filter is clean but keep in mind that this filter will still need serviced even if
it does not look dirty, the oil used to coat the filter in time will evaporate so for maximum protection
I recommend removing inspecting and oiling the filter from time to time.

Below is two other Pilot filters that were not running the pre filters on the same ride.

Here are the filters getting ready to be washed in preparation for the next ride.

My second generation pre filter design is working out good, I guess I bought large enough 
filters and they provide enough filter service area, even when they got as dirty as you see
in the above pictures my jetting was not affected enough to worry about changing pre filters.


Fiberglass Airbox Lid
Now you can buy a fiberglass replica of my mod if you don't want to fabricate your own cover.
Here is the filter I used as the pre-filter.

This will also let me see how much dust and sand the K&N filters will pass.
Why use foam filters (1-7-01) I read this in Dirt Wheels magazine
This is what CT Racing has to say about K&N filters Wiggins Prefilter Mod The DC NEW PREFILTER SET UP 350 Airbox mod Pilot 4 Inch Intake On a side note both the box modification and the Prefilter modification is another invention brought to you for free By hoser.. Enjoy! More Great Ideas Here --->