Motorcycle Exhaust System Discoloring and Maintenance

Most motorcycle manufacturers do not offer warranty on exhaust systems in regard to any discoloration (something what is often misunderstood by dealers that a manufacturer has no warranty at all on exhaust systems, but that's another story). Anyway, I might add that any internal combustion engine will cause pipe discoloration for the obvious reason that exhaust gases are extremely hot. Another cause for exhaust system discoloration and damage is that all the fuel is not burned in the combustion chamber; some also ignites in the exhaust pipe especially near the head. Excess heat equals high rate of discoloration and will, in time, damage the exhaust system. Water-cooled engines offer the possibility of less or no exhaust discoloration since temperatures are more controlled and more consistent than air-cooled engines.

Exhaust pipe and muffler discoloration will not be as much an issue in the next five years or so when most air-cooled engines will be forced to adapt liquid-cooling. Future Thai environmental and emission standards will ensure this. Well already see that more and more of our beloved motorcycles and scooters small or big are being adapted for liquid-cooling.

Back to the exhaust discoloration, motorcycle manufacturers have every right to not warranty exhaust system discoloration, as it is part and parcel of any internal combustion engine. One proviso is that we have encountered exhaust systems, mostly aftermarket products, where the chroming is contaminated or improperly applied in some – but rare – production runs. If a exhaust pipe bubbles after startup or discoloration happens from header to muffler in a short period of time, then warranty should be given and in my experience it has been.

The aftermarket has been innovative in combating exhaust pipe discoloration. I can remember that a few years back, magical exhaust pipe discoloration removal chemicals were developed. Most did not work. Some worked, but also removed a good amount of the chrome layer. On some modern motorcycle you can now find a multitude alternatives, such as painting the heater exhaust pipe with heat-resistant paint. Another was packing the exhaust header pipe with grease, which, theoretically, bakes on, preventing heat from discolored exhaust pipes. Another is taping the exhaust header pipe with titanium warp... I have tried all these fixes and have found them to be hit-and-miss cures. The titanium warp seems to protect the exhaust header pipe the most, but is also the most expensive solution. Development in heat-resistant paint has made big steps and spray-paint-cans are available that can resist extreme temperatures...