Dark spark plug, and dirty airbox

[joseph2021]

Hello everyone,

I am doing the 6k miles 125cc chinese scouter maintenance and i found two anomalies:

First, in the airbox and behid the airfilter, if found this dryied dirt. I changed the airfilter which seemed clogged (blocks light much more that the new one). I couldn't find the infiltration path, no damage to the gasket or anything, any idea on the cause? 
Edit: The oil was extremly dark when i changed it a week ago (after 1200 miles)
As in: 



Secondly, the spark plug is dark and to my knowledge, this is a sign of a rich mixture as a good mixture should give a brownish color. Now before tinkering with the carburator, i want to ask you if the mixture richness can be caused by a clogged airfilter?
Also, in quick decelarations i have bangs in the exhaust pipe, i guess it has to do with the rich mixture right?


Thank you.

[scooter7878]

Usually backfire in muffler on a decel is lean but that plugs def rich but the dirty restricted air filter will cause that get a new plug and make sure the air filter is clean and keep a eye on it

[joseph2021]

I changed the airfilter anf cleaned the plug. My last gas milage test gave 59 mpg, hopefully the next test will give better results.

[scooter7878]

Jul 29, 2021 7:44:17 GMT -5 joseph2021 said:

I changed the airfilter anf cleaned the plug. My last gas milage test gave 59 mpg, hopefully the next test will give better results.

. Cleaning isn't always the best choice for a plug for one it's harder to tell how it's running now bc plug is discolored no matter how much you cleaned it and a plug can foul past the point of cleaning and never work correctly but lmk how u make out

[joseph2021]

btw, wouldn't a breather pipe deviation, that would make it eject the oil vapors outside of the airbox, be beneficial in terms of carbon deposits on the plug/piston etc ...?

[scooter7878]

Jul 29, 2021 14:39:13 GMT -5 joseph2021 said:

btw, wouldn't a breather pipe deviation, that would make it eject the oil vapors outside of the airbox, be beneficial in terms of carbon deposits on the plug/piston etc ...?

. Yes a few different manufacturer make them they screw in where dipstick goes

[joseph2021]

Okey it went up to 76mpg, how does it sound to you?