Installing Wr250X Muffler

I have a 2009 WR250X that is all stock. I'm looking into putting a new muffler on (I hear the Q4 is a good choice) and am wondering if there is anything extra I need to do besides just take off the stock muffler and slip on the aftermarket one? Catalytic converter removal? I've heard something about an EXUP valve too? Any help is appreciated!

The cat and EXUP valve are contained within the stock muffler, so removing the stock muffler automatically removes the cat and EXUP valve.

There is an electric servo motor below the battery that pulls on two control cables.

These cables are what opened and closed the EXUP valve.

Once the stock muffler and EXUP valve are removed, you should also remove the control cables so they won't snag on anything.

From there, you can either:

1) Leave the electric servo motor in place.

2) Remove the servo motor by unbolting it and unplugging it from it's electrical connector.

If you unplug it and run the engine, you'll then get some things showing-up on your speedometer telling you that the servo motor is no longer there.

One is an orange light on your instrumentation meter known as the Check Engine Light (CEL).

You possibly could get a number displayed on your speedometer (trouble code) telling you the servo motor is not working.

You can either ignore the light and trouble codes, or plug either a home-made or store-bought thingy into the connector where the motor used to be to get rid of the orange light and trouble code.

These thingys fool the bike into thinking the motor is still there.

On top of all that, you would get a MUCH better running WR-250X by installing a fuel programmer like an FMF Power Programmer.

This is the fuel injection version of a jet kit for a bike with a carburetor.

In fact, I believe this is a must-do.

Actually, I'd add one of these before I bought an aftermarket muffler if money were tight.

I'd also remove the airbox flapper, remove the Air Injection System (AIS), and either install a smaller front sprocket or a larger rear sprocket for lower gearing.

Just be sure to keep all of the original stuff, as I believe your state will have mandatory equipment checks (for stock exhaust and cat) in the very near future. Arnie signed it before leaving office.

Thanks YZ that info helps out alot! I think for now I will leave the servo motor in place and avoid the CEL coming on.

Yamaguy I think you are right about the equipment check. Just one more reason why I want to get out of this state so bad!!!

Thanks YZ that info helps out alot! I think for now I will leave the servo motor in place and avoid the CEL coming on.

Yamaguy I think you are right about the equipment check. Just one more reason why I want to get out of this state so bad!!!

We now have some of it here.no escape.

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