2004 Yamaha YZ250 - Black splooge, please help....

[Aftermath]

No matter what I do, there is always black splooge coming out of my exhaust during a ride. I have changed to a leaner needle (still 2nd clip from top), gone from (Stock-) 180 main to a 172 main, 50 pilot to a 45 pilot, 2.5 turns out on air screw out. Altitude 1700m, mix 40:1. Bike runs superb, just messy swingarm etc afterwards......Please help (Someone that has managed to sort this out)

 

[KX02]

Make sure that you are running a good fuel/oil combination. If your altitude is 1700 M you probably need very lean jetting. Look up spanks jetting guide on this site or google. Start by finding the highest idle point with your air screw to determine the proper size pilot. That usually gets rid of the bulk of the spooge. My bike came with a 50 pilot also. I had to drop down to a 42 pilot and a leaner needle. It runs great and has hardly any spooge.

 

[FoxRocks]

Here are the links that helped me the most, provided by another DR member.

http://ericgorr.com/techarticles/carbtuning.htm

http://justkdx.dirtrider.net/carbtuning.html

Hope that helps.