Most instructions you find on the Internet tell you to cut a 3" x 3" hole in the top of the airbox to replace the standard airbox opening. The problem with a plain hole is that water splashes on top of the airbox (evidenced by the mess you find there after riding through a mudhole) and some of that water can easily run into the airbox. A better solution is to line the new airbox hole with a neoprene liner that creates a water dam.

These instructions contain photos of the complete modification process and even provide a full size drawing you can print to make a template for cutting out the hole. These modifications were done to my 2002 DR-Z airbox.

Remove the seat to expose the airbox. Fold back the electronic module. It simply lifts off the molded pegs. Remove the existing neoprene airbox tube.

Remove the left side panel and remove the air filter and place paper over the carb opening.

Cut out the pattern and mount it with double sided tape on heavy cardboard or light aluminum and then trim the pattern to the inside of the line around the new airbox hole drawing. Place double sided tape on the back of the pattern. Place the pattern over the existing airbox hole and align it with the right rear of the existing airbox hole. Scribe around the pattern with a needle or a thin scriber and hold the pattern in place to keep it from moving.

Cut out the plastic on the INSIDE of the line using a Rotozip tool, a Dremel with a Rotozip bit, or a soldering gun. Better to have the hole a little too small than too large. File the hole to the correct size using a very coarse file.

Purchase a 3" MJ (mechanical joint) clamp for 3" ABS pipe. I purchased one from Canadian Tire ($4.49CDN) and one from Home Depot ($5.68CDN) and found they varied slightly in size. The CTC one was 10.75" circumfrence and the Home Depot one was 10.875" circumfrence. The palns shown are for the smaller MJ circumfrence. You can always make the airbox hole bigger to fit the bigger MJ liner.

Remove the neoprene liner from the MJ clamp. Look inside the liner and you will find a lip. Flip the liner inside out so the lip is on the outside circumfrence. Test fit the liner into the new airbox hole and adjust the hole size as required to get a good fit.

Trim the MJ liner to length. The liner should be cut off 1/8" above the lip. Stretch the liner over a 3" ABS pipe if available or any other item such as a food tin and using a 1/8" guide between the blade and the lip carefully trim around the circumfrence to cut the excess material off. Use a razor blade or razor knife or even a pair of scissors. Trimming will be easier if you dip the neoprene in hot water for a minute before you trim.

Place a very small bead of RTV all around the liner below the lip that sits on top of the airbox. The bead of RTV should not be bigger in diameter than a pencil lead.

Place the liner in the hole with the long side down into the airxox and the lip on top of the airbox. Wipe off the excess RTV. Let the RTV dry for 30 minutes or more.

Clean out the airbox to remove any plastic chips. Remove the paper covering the carb intake. Re-install the air filter. Replace the elecrtonic module and re-install the seat.

You're done, congratulate yourself for doing a good job!

File last updated June 19, 2003

Please send correspondence to: wyliecoyote@igs.net