free mods



To get your bike to rip, do the freemods (throttle stop, grey wire, open up airbox) and throw on an exhaust sysetm / slip-on muffler. Get yourself an adjustable fuel screw and a JD jetting kit for ease of jetting your bike correctly. There is a few horsepower just to be had by jetting correctly. If you don't have to be quiet, a '05 YZ250F muffler is a very cheap (ebay!) way to increase performance. MX race pipes add even more power but are way louder.

free mods are here

Also, use the search function (top right hand corner) and search for what ever you like as there is a heap of information here at your fingertips.

He guys. Just got a new 13 WR250F yesterday. Only have about an hour of time on it. I came from a 98 YZ125, and I figured that with the increased displacement and 6 more years of technology, that even corked up it would be a pulling ride. I am kind of disappointed to be honest. But have seen the dyno runs and there is a LOT of power being robbed from the machine stock.


 Anyways. I want to do the mods, and free this thing up, my question is that I notice all of the free mods are related to earlier model bikes. Are they still applicable to 13 models? For example, I opened the muffler to take examine the baffle, and it looks completely different than the walkthroughs. Just erroring on the side of safe before I do them.


 Next question is what needs to be done AFTER the free mods? Can I just do them and ride? Just don't want to do them, and find out later that I should have re adjusted something else. I have ridden for years, but have never owned a WR.


 Again, I know that there is a lot of info out here already posted, just want to make sure that it is all still applicable to a 13 model.

The free mods info in the FAQ on these forums is out of date, so other threads were started by riders of newer models to help compensate for that.


2007 to present WR-250Fs are the same machine, so that right there will make it easier to find the info you need.


Read this thread for starters:


One of the things I wouldn't bother with in that above thread is actually cutting the plastic of the airbox below the battery.

Removing what are called the "snorkels" (intake silencers) is required, though.


On my 2009 model (same as your 2013 model with different decals and rear fender color), I went with Yamaha's accessory AIS Removal Kit.

Comes with parts and instructions, and after I got done with my bike, it ran very well.

Here's a PDF file of the AIS Removal Kit instruction:


I was able to install all of the carburetor parts without removing the carburetor from the bike, by the way.

Awesome info. Thanks. Could you explain the AIS? I have never been exposed to this system.

AIS = Air Injection System.


This collection of parts basically plumbs fresh filtered air from the airbox into the exhaust in order to pass EPA regulations for dirt bikes.

Thanks. Knowing exactly what this thing does makes it a lot easier understand why it's useless to us.

Have you changed the throttle stop? Wrs will only get 1/4 throttle from factory

Sure did. I did all the mods, and it's really opened up the bike a lot.

Does any one have any pics of how to remove the snorkel and open up the air-box for a 2008 WR250F?  I have seen the vid's on youtube for the 2006 WR but unsure whether or not they are the same.


Second, I have seen 1 or 2 pics on how to remove 1/2 of the internal exhaust baffle by cutting it out with a drill, if you have any info on this it would be great.  I have already changed out the external baffle and want to open up the internal part of the stock exhaust.  Do I have to remove the exhaust from the bike and dismantle it?


Lastly, I will be installing JD jetting kit and R&D Flex Jet Fuel Mixture Screw after the above is done, is it best to remove carby or can it all be done while carby still on the bike?


Grey Wire already done, Throttle stop and AP Oring will be done with the above.


Should scream..... I hope


Chizz Guys

I am actually doing some bike work in about an hour or so . I have a 13' so it will be the same as yours. I can take pics. I also have the external baffle removed, and will be drilling the second one today inside the exhaust today. I will document. My JD jetting kit and AIS removal kit is also being installed today.

The snorkel is really easy though. Just take off the two screws to the rear of the seat, then look down in. There is a silver cover plate with Phillips screws. It's right behind the battery. Take those out and it pops straight up . Takes 5 min.

PM me if you have questions.

And yes. Even just the free mods really opens the bike up.

Do a search for the exhaust thread started by dodjy, there are A LOT of pictures. Read this before you start drilling. Think about what your actually doing an why. It will make sure you don't go too far. And also really clear up the process.

Sorry for the separate posts. I can't type very long ones with just the app.

Awesome Lima,


Look forward to your pics buddy.  


Are you also going to cut holes in the Airbox and install mesh filters?  Or just run with removing the snorkel??

From what I have read, there isn't a solid benefit from the added holes, although it will be opportunity for air, not sure it's really functional. Differing opinions. The snorkels at a min though.

YZEtc replied this to me earlier.


"No, the airbox on 2007-and-later models is different from earlier models and there are no molded-in parts to cut out if you choose as the earlier bikes had.

Some guys have posted pics of them having cut the top of the airbox directly below the battery, but since the battery blocks this, why bother?


On my 2009 model, I removed the snorkels and that was it for the airbox mods for me."


Snorkel it is.

Here are the two seat screws

ImageUploadedByThumper Talk1406394831.378441.jpg

Here are the screws holding the snorkel cover in place. I put my cover back on after I took out the snorkel. Up to you.

ImageUploadedByThumper Talk1406394893.739251.jpg



cheers buddy

AIS removal on 13 WR250F

Note: I am not a bike mechanic, and this is just how I did mine. I am not an expert. You assume all risk working on the bike yourself.

Ok. Enough of that/ :)

So take off the seat and gas tank as noted above.

I agree, the directions are crap. The hose to the "carburator" doesn't even exist. It actually goes to the head.

First take off the mounting bolts from the frame that hold the AIS.

ImageUploadedByThumper Talk1406397790.849126.jpg

Then, remove the Hose clamp on the head. You will see a large aluminum pipe sticking out.

ImageUploadedByThumper Talk1406397880.658028.jpg

Next, remove the Allen securing a ground wire and the base of the AIS to the front of the engine.

ImageUploadedByThumper Talk1406397959.347887.jpg

Next, go to the left side of the bike, and remove the clamp holding the hose to the top of the airbox.

ImageUploadedByThumper Talk1406398027.421091.jpg

Remove the clamp to the airbox side to prevent it from tearing any other hoses when you pull it out.

Next, you will see that there is a zip tie holding a wiring harness to the AIS. Remember to replace this of your taking the whole bracket off like I did. The bracket is not used for any support or wire routing, and therefore was not necessary on the bike.

Next go to the right side of the bike and remove the small hose clamp on the backside of the right side of the head.

Sorry no pic, phone died.

Now you can pull the entire assembly out.

Next, starting with the main intake on the front, put the exhaust fitting insert and cover in. As stated by other users, this clamp is crap, and stripped very easily. The issue is that the cover piece they give you is pretty thick, and doesn't give much. Even with the new pipe clamp. It took quite a bit before I felt it was tight enough.

Don't forget to heat up and cool down, and make sure this is rightImageUploadedByThumper Talk1406398469.263474.jpg

. I'm still not set that this is good enough not to fall off. Will need to check again later, either way, just pay attention to this.

ImageUploadedByThumper Talk1406398257.534174.jpg

Next, find the smallest cover/nipple. I trimmed mine down as it was stupid long. Another disappointment from a 50 dollar kit. Then instead of re securing with the orig clamp. Used a zip tie.

ImageUploadedByThumper Talk1406398647.675640.jpg

Next , place the largest cover on the airbox. Secure with zip tie. Again, old clamp is too loose.

ImageUploadedByThumper Talk1406398700.382066.jpg

And that's about it. Take care with the open holes in the bike while your working. There really isn't a required order, and feel free to cover ann opening as soon as you remove a hose.

Next to throttle screw removal in 2 minutes. I just cut mine down, but will install proper one as I left mine an eighth of an inch long. Too long ok, too short bad. I found a trick on TT posted previously to make this removals snap.

I wrote this all down from memory. Let me know if anything looks really off. Enjoy! Feel free to contact me if necessary.

ImageUploadedByThumper Talk1406399014.942678.jpg

Looking at the pipe that was removed, you can see it is notched to allow the pipe to be tightened evenly around the OD. Think I will Dremel a few reliefs in myself since it still can't be made right enough.

Awesome mate,


Keep em coming for the exhaust.


You gonna jet the carby also?

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