Honda XR250R Exhaust Mod (Uncork) by Stuart Moss on 4Strokes.com

4Strokes.com Honda Technical: XR250R Exhaust Mod (Uncork) by Stuart Moss

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This image shows how I used a 1/4" flat blade screwdriver wedged in the hole in the stainless steel cover where the Torx screw was. Note that this is done in conjunction with wedging the screwdriver between the outer stainless steel shield and the baffle as shown in the image to the left. Don't use too much pressure or you will deform the stainless steel shroud. The steel on the baffle you are pushing against is not that strong, so do not use too much pressure. The stainless steel shroud is not that thick, and since this is a round hole, there are only two points where the screwdriver will make contact, so it will be fairly easy to ding it up if you are not careful. If you look closely, you may be able to see a ding where the upper part of the screwdriver blade rests against the hole in the stainless steel. It is very slight.

Use screwdriver to wedge baffle out This image shows how I used the screwdriver to wedge the baffle out by applying pressure against the stainless steel shield and the outer wall of the baffle. The screwdriver blade is slightly cocked because I was holding it with my left hand and the camera with my right. Unless you bend the screwdriver blade to grab the lower lip on the baffle, which extends down about ½", you will have to just apply pressure against the baffle and work it out by wedging the screwdriver against the stainless steel shroud. Remember to alternate wedging points 180° around this stainless steel shroud. You may want to try to (gently) apply pressure against the mounting screw hole every once and a while. The 1/8" pilot hole adjacent to the exhaust hole came from a brainstorm I had after reading a message in the 4Strokes.com Honda Forums about someone that drilled out three or four ¼" holes tapped for a ¼" screw. The poster said he could adjust noise/power by the number of open holes, in effect tuning the exhaust. Stupid me, couldn't wait until I removed the baffle. I learned that the other side of this outer plate was blocked inside the spark arrestor by the baffle inner friction mount when the drill bit hit solid metal once through, so the exhaust doesn't come through this portion. I made this hole for nothing.

File down inner mount for easier removal/install Once the baffle was removed, I put it in a ½" drill and used a file to remove a little material off of the inner mount. You will only need to remove about 0.001" or so. It doesn't take much material removal to allow the baffle to slide in and out easier. I probably used 50 or so revolutions of the drill applying moderate pressure on the file to this inner mount. Try inserting it every once and a while to ensure you are not taking too much off. Now it is an easy task to install the baffle for "stealth" mode. I just use the Torx screw to secure it.

Stock and modified exhaust Remember you should also remove the air box snorkel and if possible, grind or file down the inner weld bead on the exhaust header. Each pipe has this bead where each pipe mounts to the engine. Once you remove the header pipe you will see the restriction and understand what I'm talking about. It took 2-3 hours with a half-round file and a lot of elbow grease to remove (didn't have a grinding stone). You should also get a UNI air filter with the hi-flow frame design and get rid of the (restrictive) stock Honda air filter.

I'm still waiting for my UNI filter, but just removing the baffle and snorkel gave me a significant increase in power. It also reduced the off-idle hesitation a lot. It now looks and sounds more aggressive. It's a lot easier to keep people out of my way when they hear me coming when I'm on the road. If you haven't guessed, I drive somewhat aggressively. I could not feel any difference after removing the header weld beads (snorkel and baffle had been removed). Perhaps once I install the UNI air filter I will see the benefit of that mod. Nevertheless, it breaths a lot better now. A LOT!

Credits: Article was originally written and posted in our forums by Stuart Moss and editing by 4Strokes.com.

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