blowing black oil out tailpipe jetting?or any help

[oldschool]

hey being new here i have tried to search and didnt find anything on this so i wanted to post a question and see if i could get any help.i have 2 2003 kx100s(girlfriend,and her daughter)and a 2006 kx25o 1 of the kx 100 and my 250 leave a black oily residue out the exhaust the kx 100 REALLY badly as in runs off the swing arm though it does  lube the chain it is still a pain.i run maxima castor 927 oil at 32 to 1 in all bikes and 2 out of 4 leak unburnt oil  they both have factory jetting 100 has factory exhaust still running a 138 main jet can i just change the main jet to help with this or is there another carb trick?maintenance is kept up but they still have factory top ends -never had any problems both bikes run GREAT just OILY 91 octane only.any ideas ?thank you!

[DoldGuy]

OldSchool,
Welcome to the site. Maxima 927 is good stuff & good @ 32:1. Kawasaki has been safe on there jetting to the rich side. Install a new plug and ride the bikes in a normal riding condition, then check the plug color (from your description it will be almost black & probably damp). Drop a main jet size & check again (probably still black but not damp). Continue this until you get close to a Mocha color. Also keep in mind if you plan on running in a different situation where you will be at full throttle for extend periods, you should go back up on the main to be on the safe side. You will also need to repack your silencers as the current is saturated & will continue to spooge the goo.
Hope the info helps & keep us posted.
DoldGuy (from the oldschool )

[Hillclimb#42]

Good advice from Dold School-guy. I also would mention, putting a 2-stroke around loads up the silencer with unburnt oil, then ripping for a little while will clean out the silencer by blowing it out. Running real hard will get it red-hot and have it smoking like its about to catch fire. None of those are a huge issue really. Its not like you can tell the gf and her daughter to start ripping all the time or quit taking it easy and safe. Jetting to their style may be the answer. Keep your changes in mind when they start getting faster, or instead of rejetting, remind them to pull the clutch in and clean it out, when in the tight stuff, where riding speeds and rpm's are low. A little "brrrraaap, brrraap" with the clutch in, helps. Changing the packing every season with their bikes is a good idea, but that oil falling out onto the swingarm happens to all 2smokes at some point or another. It gets loaded up then cleaned out in a cycle. you just have to be aware that they do that.
  That's a cool thing you're doing for them. I know that's alot of work from experience.

[oldschool]

cool thanks alot guys i found the carb had the factory main jet 138 dealer only had a 130 so i will try to find a 134+- but considering these kx 100's never see wot(wide open throttle) i am wondering if my main issue is the needle setting anyone know what slot there clip is on for the needle?pilot jet?I was going to try moving it down 1?or 2? slots and try it too see what happens thanks again

[kaw rider]

I would change the pilot and needle adjustment.

[Just an old rider]

 I was having the same problem with my sons bike a 98 yz 125 we picked it up recently and thought it was a oil leak.. then I changed the oil and the oil was clean so I figured it was unburned oil ... My boy being 12 is not to hard on the throttle yet so I got on the bike and had some fun ... took care of the dripping for now ....