The ones that I have looked at also looked like that. It is quite clear that the exhaust gasses are leaking past the reed valve on these systems. Just one more reason to blank them off and be done with it.
Can anyone tell us what would be the harm if it was left as is and continued to collect carbon until it clogged up completely? I haven't looked at mine recently, but it did have some carbon built up on it the last time I looked. I scraped a little off, but gave up and just closed it up with most of the carbon still on there.
Well, intuitively you could say that when they get completely occluded it will be like having blanking plates in place, no more PAIR airflow from the airbox into the exhaust stream.
Here's the description of the PAIR system from the FSM:
AIR INDUCTION SYSTEM
The air induction system (AI system) introduces fresh air into the exhaust port in order to burn the
unburned gas (which is present in the exhaust gas) in the exhaust pipe. The burning of the
unburned gases in this manner enhances the efficiency of the catalyst and results in cleaner
exhaust gases.
The AI system takes a portion of the air from the air cleaner, sends it to the reed valve via the air
cut-off valve, and introduces it directly into the exhaust port through the reed valve.
The air cut-off valve is controlled by the signals from the ECU in accordance with the combustion
conditions. Ordinarily, the air cut-off valve opens to allow the air to flow during idle and closes to cut
off the flow when the motorcycle is being driven. However, if the coolant temperature is below the
specified value, the air cut-off valve remains open and allows the air to flow into the exhaust pipe
until the temperature becomes higher than the specified value.
The reed valve is provided on the cylinder head cover above the cylinders, and sends air to the
exhaust pipe through the inside of the cylinder head.
So the only downside of having blocked off PAIR system is the emissions may be somewhat higher.
