When I purchased my 2006 Breva 750 a year or so ago, I noted the chrome on right side muffler, just behind the exhaust header connection and extending back about ten inches was discolored to a deep blue. I assume this was the result of the catalytic converter in the right muffler overheating at some time in the hands of a prior owner.
The bike has had surging problems in the 3-4000 rpm range. I have tried a variety of maps, and equipment changes, including even the installation of a new ECU. No matter what I do, the problem returns.
So, now I’m thinking about the catalytic converter. I have used the highly unscientific “finger over the exhaust outlet test” to measure exhaust flow at idle. I can detect no difference between the right and the left. I have no idea about exhaust flow at speed. What’s not clear to me from the several threads I’ve followed regarding badly overheated Cat Converters, is why does the muffler need replacement (Emission issues aside)? Does the muffler’s blue discoloration mean the exhaust flow necessarily is restricted by the converter? Can this affect the signals from bike’s single O2 sensor mounted in the crossover pipe connecting the two exhaust headers and thus sending bad data to the ECU?
I have run maps which disconnect the ECU, but the surging remains.
Many thanks for good ideas.
