Black spark plug

[svtman79]

I just pulled my plug. It was jet black, and smelled and looked like is was covered in gas. What would cause this? I just put new boyesen reeds in it and desert pipe on it about 5 miles ago. I plan on doing some carb tuning tomorrow. I have 3 mains and 3 pilots to play with other than the stock ones. I am running 50:1 motul 800 and 93 octane in it now. I have only put about 8 to 10 gallons through it since I have owned it. This is the first time I pulled the plug. It other wise runs great.

 

[weav6385]

Sounds like you will have to re jet the carb. I dont know the make of this bike but I would call a shop and see what they suggest you run in it. For now try to adjust the air screw. Start with it 1-1/2 turns out then start the bike and turn it in until it runs at its highest rpm but still has a good "ping" to it. That will be a close start. Take the bike for a ride and do some holeshots moving the srew about a 1/4 turn each time until you feel what is best. Jetting is a pain in the ass.

 

[domino dave]

Good to hear your bike is running well ... It will run even better when you get it jetted properly. Search the threads here for "jetting", and get ready to do a lot of reading. Dave

 

[svtman79]

The bike is a 1999 KDX220. I did get it re jetted this past weekend. The bike is running great. It was rich on the bottom. I can now wheelie in 4th, but it is a little hairy in the mud.