This is a complement to my post called F650 Dakar preparation for Africa/RTW and a response to the post called unleaded with a cat?.

From what I understood on f650.com and by talking with my mechanic, you can drive with leaded gas for quite a while (weeks? months?) without any other problem that you are going to kill the catalyser. Beyond that, you might clog the catalyser and develop engine problems. I'm not sure what it means, I never heard of anybody who had taken a catalyser for several years in leaded-gas areas. Apparently everybody gets an exhaust without cataliser out of safety (or paranoia?).

A much cheaper solution is to remove the catalyser. Someone asked me how to proceed. Here is the response I sent him...

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I first read the tip about the catalyser on f650.com but I felt much more comfortable doing it after talking to my mechanic because he seemed familiar with the operation. I guess he had never done it before but at least he had heard about it and it did not seem to be any problem at all:
1) Cut open the rear of the left-hand-side pipe (which is the catalyser) a bit like a cap that you would remove from a tube, approximately half-a-centimeter from the tip of the cylinder (see the red lines on the picture).
2) Cut off the 3 anchor points of the catalyser itself inside the cylinder and remove the catalyser. The anchor points are distributed like the branches of a Y - the catalyser being held at the intersection, in the center of the cylinder.
3) Weld back the tip of the cylinder that was removed.

I don't remember however if he did the last operation himself (the welding) or if he had it done at another workshop because he did not have the proper equipment to weld that kind of metal.

I paid for each bike 18 Time Units (the BMW Time Unit is 5 minutes) at a cost of 3.75 euros each for a total of 67 euros (20% taxes included) for 1-and-a-half hours of labor. The cost of the Time Unit changes depending on your country.
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Hope this helps,

Pierre Saslawsky
http://www.photobiker.com