Carbon pattern in exhaust ports. Have you seen this?

[motoshrump]

After 14+ years of being on the XX I decided to remove the header and have it glass beaded & repainted.

Upon removal I felt obligated to check out the exhaust ports and to my amazement the carbon laid down on the

surface of the ports has managed to produce an interesting pattern. On each cylinder there is one exhaust valve port

that has a typical amount of carbon (no scale) while the other has absolutely no signs of carbon what so ever.

I couldn't have cleaned it better with a sand blaster, a clean bright cast aluminum is all that I can see. The exhaust ports

have a fine ridge cast pretty much right down the middle of the port and that produced the defined line between the

carboned side and the clean side. The pattern is mirrored between the four cylinders so unless I have cam lobes wore off

of all four I don't know how this is possible. The bike has a Dynojet Stage II jet kit with a BMI air filter and stock exhaust.

I have had no issues with throttle response/jetting and the bike has only 40,000km. I run the Iridium NGK's & Honda GN4 10W40.

Oil consumption is minimal.

Has anyone ever seen this before? I can provide a picture if necessary.

Thanks in advance.

[HANKSXXX]

I'd like to see the pictures...

[The Krypt Keeper]

i would also like to see the pictures.

don't know what its from, but i enjoy seeing weird stuff.

[motoshrump]

I uploaded a couple of pics, not the best resolution but it gets the point across. And no that is not a shadow in the exhaust port.

They are both under my only Album.

Let me know what you think,

Thanks.

Here is the other one.

[TuffguyF4i]

All i can say is that mass flow is a weird thing. In the engineering world, many times things are designed and tested many times before a final design is completed. This is because things are difficult to predict.

[cbrxxquad]

too rich I am thinking.