I’m not a physicist, the combustion has peak temperatures and they occur at some point? Mixing air and fuel has some peak point in derived combustion temperatures. This device prevents that from occurring, it is timed or configured to open when that occurs typically. Adding the exhaust gas will do that, but seeing that Nitrous oxide production occurs at 2500 degrees really confuses me, that must be an internal flash temperature potential? Seems very high to me. Adding exhaust to the air keeps that from occurring that peak flash temperature in the combustion chamber.

The EGR opens and closes, its not always open but must be opening in a range that has the highest potential for that highest peak combustion temperature. So you never get to that peak with it operating correctly.

Now it is gone and you have an over all lower temperature on the head? But inside the engine you now have these flash points that are higher.

Man you have a lower average temp but you now have these peaks. The fuel to air mix and firing timing? The same as before in some of the range but in other parts of the throttle range you now do not have the EGR effect. Your getting these flash points that are hotter and that could be affecting the plug.

How does the time of firing work on these bikes, is it electronic? Its not fuel injected its mechanical so in some instances the fuel to air mix and firing is not correct. That would be the range that the EGR was in effect. I am not taking mine off because I cannot ignore that that bikes configuration is set for it to be there. A bike that did not have one from the factory would help, how is set up? Is the timing preset in the CDI or can it be adjusted? The carburetor may need adjusting to or in the range that the EGR operates, when is it open and when is it closed? Which jet is in effect in that range.

A white plug is a sign of the fuel to air mix being off or the ignition timing. Maybe I am wrong but it is currently configured for the EGR being there.

Everything has a range, it has high points and low points setting are configured to accommodate the range.

Put the EGR back on and then put in a new plug, then check the plug. Process of elimination if that has an effect on the plug then what is different and why.

I think the EGR opens in the midrange…..it not open at idle and closes at upper range to full throttle I believe. Other removed that device but they also added performance exhaust and increase the jet sizes? They may have set it better to operate without that device by doing that?

The half color is a sign of an uneven ignition and all related to fuel to air and timing. The EGR is integral in that….