F650 Classic Cat Converter FAQ

compiled & edited by Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.
Last Updated: 14 June 2007, by Winter #1935

Other related FAQs:


This FAQ is about how to remove the catalitic converter from a Classic F650. If you have a GS/Dakar please see the GS Exhaust Modifications FAQ.

Pardon my ignorance, but why remove the cat?

Unleaded gas isn't available in some parts of the world. Leaded gas will ruin the catalytic converter. And a cat gets ruined by melting and effectively restricting the exhaust to where the motor will no longer run. THAT will ruin your day.

Cat Converting

Method 1 - Cutting open the SIDE of the Exhaust

by Mike #410

You should be able to tell where the hole was cut by looking at the pictures (at the end).

Method 2 - Cutting open the SIDE of the Exhaust


I did it and the way its shown (above) is not the best way. Cut out a triangle forward of where its shown in the pictures. Then cut the can/cat out that will be much easier for your welder. If you do it the other way you will agree with me after it is done. Here is what you should do:


Q. After learning this morning that my Rotax muffler does not work with the Jesse mounts, I took the OEM muffler down to the local Mexican welding shop to have the Cat removed. I need to be able to use Leaded gas if no other option is available. They cut, removed, and welded, but they did NOT find a white honeycomb piece of ceramic as I have heard Catalytic Converters look like. Instead, they found and removed a whole bunch of stuff that looked like steel wool. WAS THAT THE CAT? Or did we merely remove the "muffling" agent in the muffler. I went back today and had my friends "touch up" the muffler a little and remove the real CAT. Didn't realize an ILLEGAL procedure such as this would be on the FAQ, but there it was when I got home last night, so I took that info back to the welder. With all the cuts and welds and crap all over the inside of the muffler now, it looks more like I mutilated the cat, than killed it. But with all the muffle gone, it sure sounds throaty for a Beemer... NewMexEd

A. You will always find a cat as close to the engine exhaust port as it can be placed in order to keep it nice and toasty, so look for the first bulge that you see in the exhaust system snake. It is likely to be hiding there. The steel wool is likely the muffling material. Richard #230