too much black spooge

[Slipstream27]

Hey guys, I have the 04 KDX200 torn down to get the suspension rebuilt. With it torn down, decided to put all new bearings in the wheels, linkage and swingarm. With the carb staring at me, I took it apart and cleaned it. The bike runs good, never fouls the plug, but the black spooge is excessive. Yes, it smokes, too, but Im stumped on what to change.
I have the FMF Gnarly woods pipe and Turbine core 2, Boyesen super stock reeds, No-toil air filter, snorkel removed, stock carb with 150 main, 40pilot, R1174K needle with clip in top groove. Im running non ethanol gas with Lucas semi synthetic at 40-1. We mostly ride between SL and 1500 ft. Mostly tight trails, but we never miss a chance to open it up, and it never hesitates.
Everyone says change one thing at a time. OK, here is your chance: Where do I start?

I am considering buying a new carb, but maybe thats not necessary.

[SpruceItUp]

Have you changed the jet block gasket? It can cause a rich condition if it's bad.

Here's a link: https://jdjetting.com/product/jdkh47-ke ... ck-o-ring/

The kit comes with the security torx you need to take the jet block out, if you don't already have one.

You can also test the jet block gasket to see if it's leaking to begin with, though if you haven't replaced it already, it likely needs it.

Here's a good video for it:

Thank you @kdxdazz for the great video :)

On top of this, the emulsion tube (needle jet) could be the cause as well. These are a bit of a pain to replace, but I believe @kdxdazz sells them (sorry if you don't) and he has a great video going over how to replace it as well. I'd do this last, though.

It's not typically necessary to replace a carburetor. They can typically be brought back to how they originally functioned.



One last thing, and I should've wrote this first, go through the jetting guide here on the forum, it will get you dialed in right to where you need to be. It takes some work, but it's worth it in the end. Do this first!
viewtopic.php?t=1156

[SS109]

Also check your float level. Make sure it is at 18mm.

[Slipstream27]

Yes, 3 years ago when I first went through the carb, I followed the jetting guide. Also, I did replace the jet block gasket. I bought two kits, so I think I'll put the new gasket on while Ive got it apart.

As for the float height, I have seen more references to 16mm than 18mm. Thoughts???
My simple mind thinks that there is too much unburned fuel getting past the cylinder, or that maybe I should run more like 50:1. I had an 81 KDX 175 when I was a kid, and it ran on Bel-Ray at 55:1, never had the spooge issue.

[SS109]

Yes, 3 years ago when I first went through the carb, I followed the jetting guide. Also, I did replace the jet block gasket. I bought two kits, so I think I'll put the new gasket on while Ive got it apart.

As for the float height, I have seen more references to 16mm than 18mm. Thoughts???
My simple mind thinks that there is too much unburned fuel getting past the cylinder, or that maybe I should run more like 50:1. I had an 81 KDX 175 when I was a kid, and it ran on Bel-Ray at 55:1, never had the spooge issue.

Just because you replaced it 3 years ago doesn't mean the jet block gasket is still good. Check it just to be sure and eliminate it as a possible issue.

On the float height, 16mm is stock. What I and many others have learned is that setting it at 18mm helps quite a bit in dialing in the jetting and less fuel consumption. At 16mm it can make it overly rich.

Going to less oil (ie; 40:1 to 50:1), without going through the jetting process again, will actually make your bike spooge worse as now you have made the bike richer. Not saying that you shouldn't run 50:1 (with proper jetting) but 40:1 isn't your cause of the spooge. I run the same oil in my '98 KDX220 and my '11 GasGas EC250R, at the same 40:1 ratio, and don't have spooge issues unless my silencer is due for a repack.

One other thing I know can cause excessive spooge when everything else checks out and that is a bad right side crank seal. You would need to do a leak down test to confirm that.