Originally Posted by 2door
Kev, That's unusual for the Opti-2.
I too run Opti @ 100:1 and do not have the problem. In fact there is little to no oil residue from the mufflers of any of my bikes. I'm wondering of that muffler you're using has anything to do with it but I don't see why it should. As long as your engine is running good and the spark plug reading is saying things are okay, I wouldn't worry too much about it.
My plugs looks OK at very light brown in color. I think it only happens when I use the headlight as it runs via the white wire,...could it be the cause robbing power therefore the plugs not efficiently burning the fuel?