Different color exhaust ports

Bike: '99 R1100S, 15K miles, one spark plug heads, recently replaced injectors with matched EV14's. Removed the exhaust for a clutch job and found the exhaust ports on each side were TAN on the upper port and BLACK (or charcoal grey - but not sooty) on the lower port. The tan was also into the common area just before the pipe. See pics.

Does anyone know, or have an educated guess why ports would be such different colors coming from the same combustion chamber??

Left jug:

Right jug:

Closeup of "common area":

Morning Lowndes

That is pretty normal & you wouldn't even see it if the bike was ridden at high speed then quickly turned off & disassembled without idling or cold starting.

That black is mostly burned off oil reside that migrates to the bottom of the combustion chamber when the engine is turned off. Once re-started the sooty exhaust will carbon up the lower part of the combustion chamber including the lower exhaust area.

It will go away after a good high speed run out.

I guess they could have different colors because when stopping the motor, sometimes, exhaust valves get opened and fumes being hot try to get to the upper side?

Dan.

Morning Lowndes

 

That is pretty normal & you wouldn't even see it if the bike was ridden at high speed then quickly turned off & disassembled without idling or cold starting.

 

That black is mostly burned off oil reside that migrates to the bottom of the combustion chamber when the engine is turned off. Once re-started the sooty exhaust will carbon up the lower part of the combustion chamber including the lower exhaust area.

 

It will go away after a good high speed run out.

 

D.R.

THANK YOU, sir!!