I just looked at the end of my MBRP slip-on and the spark arrestor screen and tip are black. I am running a Dyno-Jet 190 main with the clip in the 3rd position. I have the lid on with a Uni foam in the stock air box. I am 2 turns out on the screw. I also noticed every once in a while I would bog and a little fuel would come out my over flow. Other than the blackness and a hiccup twice, it pulls like a monster through the gears. The temp is in the low 60's if that makes a difference. Any help would be appreciated.

 

It sounds like you are rich. I would look at the plug too. If it is dark brown or black then you are rich. As for the fuel thing, I would clean out the bowl and check the needle seat.

It's har to tell what's causing the rich condition. Do you ride mostly full throttle or mid or low. This will determine if it's main, needle of pilot respectivly.

I hope this helps.

 

Mostly it's short runs through the field through all the gears. I don't really have anywhere to open it up. I've changed the plugs once already because I fouled them out. It is an '03 with only about 10 hours on it. Dyno Jet suggested second down, but it was cold really cold when I did it and found third started and ran much easier.