Air Box Flapper Removal
Our wonderful little WR250R/X's come with a flapper on the air box intake. Why? Hmmm . . . closest I can tell is that its main purpose in life is to reduce intake air noise. I can see no other reason to have it on there. It chokes up the intake something fierce . . . so let's get rid of it.
1) Remove the seat, side panels, radiator shrouds, and the gas tank. If you have a helper near by to hold the gas tank up out of the way, you will only need to lift it for a moment to get at a vacuum hose and you can leave both the wiring and fuel line connected to the tank if you wish.
2) Once everything is accessible, start by removing the electric solenoid by removing the Phillips screw as shown here.
AIS System Removal
The AIS (Air Injection System) is a common component found on bikes with a catalytic converter. It injects clean air directly into the cylinder to help it warm the exhaust gases upon initial startup and bring the catalytic converter up to operating temperature quicker. If you go with an aftermarket exhaust, the AIS is no longer serving any purpose and will actually cause backfiring on decel. Time to dump it. We offer a kit for this which includes the AIS block-off plate, the large rubber cap for the air box and also the smaller cap needed to remove the air box flapper mechanism since most people seem to remove these two components at the same time.
1) First, locate the AIS solenoid which is under the left radiator shroud. To begin removal, first remove the metal strap holding the rubber tube in place.
2) Unplug the solenoid by pressing down on the tab and pulling the connector off.
For those that have followed my Dyno tests and subsequent airbox mods, you are familiar with the big holes in my airbox. The holes get drilled somewhere during the 2nd dyno test. Anyway, the bike has performed fantastic. I've not had any problems whatsoever. However, I've been incubating a better solution ever since. And what follows is....well....more tinkering. So bear with me, its going to take several photos. But I think you'll find it very worthwhile.
For starters, I needed to acquire a new test dummy. So I ordered a new airbox (just the main core). It was very helpful to have one to inspect thoroughly (removed from the bike). Here's what it looks like: