Airbox “Mud Flap” and “Splash Guard”


Before I departed for last weekend’s trip, I had to do some maintenance to my bike. I mounted up a new set of Shinko 705 tires, changed the motor oil, changed the fork oil, adjusted my Race Tech emulators, and swapped out my air filter.

When I separated the top portion of the airbox and flipped it over to inspect it, I noticed quite a bit of dirt had collected along the inside flange of the lid, (the area where the gasket of the air filter sits.). Unfortunately, before I took a photo of the grit, I cleaned it off. But, in the below photo, you may be able to see evidence of “muddy water” residue that has dried on the underside of the airbox lid.

I have modified my motorcycle. I do not have any of the OEM fairings on the front of the bike anymore. Because of this, water has a freer pathway where it can more easily get driven back towards the airbox. Previous to this particular airbox inspection, (With the OEM fairing configuration), I had never found dirt that had gotten “forced” between the lid and the bottom portion of the airbox before.

I cleaned the grim out of the flange, and decided to add some protection to the airbox.

Using a pair of scissors, I cut a piece of 3/32″ sheet rubber I had scrounged from work.

I then slid the piece of rubber, up behind the snorkel tube and fastened it in place with two zip-ties.

I felt, I now had an effective “mud flap” to deflect debris from infiltrating the seam between the lid and the bottom of the airbox.

Then I looked at my air filter, (I make up my own: Air Filter Modification ), and remembered the “mud stain” on the underside of the airbox lid. I thought, “Okay, I have taken care of the seam of the airbox, but what about the snorkel too?”

I started poking around the front end of my motorcycle and came up with a solution that worked.

Just behind where the steering stem passes through the bottom portion of the motorcycle frame, there are two holes that are drilled and tapped for a 10mm bolt. The left hole is used to secure a “clamp” that holds part of the wiring harness to the bike.

I removed the harness clamp.

Using a tape measure, I figured out what an appropriate width would be for another rubber, “mud flap”. I also laid out where I needed to drill holes through the rubber sheeting.

(I really needed a hole punch for doing this. Drilling through rubber sheeting isn’t the appropriate technique for acquiring a hole.).

Next, I cut off a piece of steel strapping I had hanging around……

…..and drilled two holes through it that corresponded to the threaded holes in the bike frame.

I “dry fit” the steel strap by threading the bolts through it and into the bike’s frame. Everything was “A-O-Kay”.

I then, slid the bolts through the rubber, “splash guard”….. (The “silver goo” that you see on the rubber is “Never-Seize”. I am using Stainless Steel machine bolts that are being threaded into the aluminum frame. Some corrosion is inevitable; the “Never-Seize” will help with that.)

….and bolted the unit to the bike.

I tucked the “mud guard” up into the space over the radiator and let it hang down behind the cross member of the crashbars I made for my bike. I was looking for a “natural drape” of the rubber guard.

When I was satisfied that the mud guard was in its proper place and would do its intended job, I marked where I needed to “drill” two more holes.

As I said before, drilling through sheet rubber is not a good solution. As the drill bit spins through the rubber, it tends to “fetch up” and twist the rubber around the body of the drill bit. It also, pulls the drill bit, in a sort of uncontrollable fashion, away from you. I decided on a safer solution because I was so near the radiator. I didn’t want the drill bit to “pull” itself through the rubber and right into the radiator!!!

I grabbed a mill file off of my workbench along with my propane torch. I heated up the end of the file……

…and “melted” four holes through the rubber sheeting.

Using zip-ties, I fastened the bottom edge of the mud guard to my crashbars.

Once the mud guard was fastened, I cut the excess rubber off of the bottom edge.

Here is the finished, “Airbox Mud Guard”.

Finally, I used a zip-tie to secure the wire harness to the anchor tab on my radiator.

EDIT: May 04, 2012. The snorkel tube “Mud Flap”, and the airbox “Splash Guard”, have been excellent additions to my motorcycle!

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