1983 Cb125 soot on spark plug

[Kang]

Good morning everyone. I have a 1983 cg125 that I’m fixing up. I noticed that I had squire a bit of soot on my spark plug so I cleaned it all off. 20 miles later and it’s all back. What would be causing that and how do I rectify it? Carb set up wrong? I have fitted a shorter aftermarket silencer I guess that could make a difference. Thanks in advance. 

Edited May 19, 2024 by Kang

[RideWithStyles]

yeap their all possible on all the talks, also if there is not enough air getting in but if its too rich then its the fueling first...

[Old-codger]

Sounds like carb set up wrong and running to rich, could be blocked crap airfilter or wrong/worn jets. Could be the needle jet is worn out letting to much fuel through. As the carb is over 40 years old its time to strip the carb down and check all the parts to see if the parts are worn out and if needed a new service kit.

[Grumpy Old Git]

Running rich.

 

Strip, clean & check jetting.