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Super Old thread so I’m not really expecting a reply, but did you ever figure this out canyn? I have been chasing similar symptoms for about a year. Bike runs like a top, but makes quite a bit of spoo. I’m running an RB carb 38,148, DEK #2. It seems like it dribbles a lot less with CEK #2 and runs super well, but the bottom end power of the CEK really wears me out in the woods.
If anyone can chime in about how to reduce my sooo production, I’m all ears. for what it’s worth, top end is recent, all maintenance up to date. Starts easily, idles well, absolutely rips regardless of RPM range or throttle position.

Running OEM pipe/silencer? When was the last time either was drained/cleaned out? Spooge is a part of 2T life, but you can minimize it with jetting and oil mixture/manufacturer changes. I am currently running Amsoil at 45:1 and it's a bit better than it used to be, but still drips a little

I run Amsoil Dominator @45:1. Just a tiny drip. Proper jetting is key.

jamiethegiraffe wrote: 09:47 am Oct 09 2024 Super Old thread so I’m not really expecting a reply, but did you ever figure this out canyn? I have been chasing similar symptoms for about a year. Bike runs like a top, but makes quite a bit of spoo. I’m running an RB carb 38,148, DEK #2. It seems like it dribbles a lot less with CEK #2 and runs super well, but the bottom end power of the CEK really wears me out in the woods.
If anyone can chime in about how to reduce my sooo production, I’m all ears. for what it’s worth, top end is recent, all maintenance up to date. Starts easily, idles well, absolutely rips regardless of RPM range or throttle position.

Dek is very rich so spooge would be a given, 38 pilot indicates you might be too rich on the straight diameter of the needle or wear in the emulsion tube, that bottom end hit that wears you out could also be the nature of the RB carb, power and running well is one thing but the way it's delivered is the most important thing which is never talked about, make sure you have the airbox lid and snorkel installed

thanks for the reply KDXDAZZ. No airbox lid/snorkel on my bike as it's a KDX220 engine in a KX125 frame. Not sure the 125 ever had an airbox lid?
What you're saying about the DEK being too rich on the straight diameter makes sense. When i swap in a CEK needle, it seems to like a 40pj better than the 38 and it makes less spooge. I thought they had the same straight diameter? But there's definitely a difference in the pilot circuit from one needle to the other. Emulsion tube wear was another thought that crossed my mind since the carb came used with the bike and i've put about 150hrs on it since purchase. Too bad there's no way to replace the tube in a PWK. I also think it strange that both CEK and DEK run best on clip #2 for me. Everyone else is usually talking about #3 or #4, but i've done plenty of experimenting and for my bike it's definitely #2.

That all said, the bike runs incredibly well with lots of power and no bog, blubber, or flat spots anywhere. It's a fantastic woods bike with gobs of useable, tractable power. The CEK may actually be more fun to ride, but i'm faster running the DEK needle thanks to its electric-like power curve. It's noticeably better for slippery hill climbs, loose rock gardens, and it still rips when you get on the pipe. Most notably, the DEK is easier to ride hard for longer periods of time e.g. enduros and scrambles.

I wonder if the CEK would be a little more woods/exhaustion friendly if i retarded the timing a bit via stator plate... Maybe the needle would help cure the spooge issue and the timing could help tame the hit of the needle....

I'm working with a CNC guy at the moment and hoping to have replacement emulsion tubes available by next month, will offer them for sale on here first if all goes well, it's been on my mind for years but couldn't find the right guy to make them

You said maintenance was up to date. Does that include a freshly packed silencer? Have you ever cleaned out the pipe? Have you done a leak down test to make sure you don't have a crank seal leaking?

Like was mentioned, jetting is key for anything if everything else is in good working order.

Hey SS! yes, the silencer has been packed fairly recently. About 35 hours ago i complete disassembled the TC2 including the end cap (wouldn't recommend) and soaked/cleaned everything in my parts washer before burning out the residue and reassembling with fresh packing and silicone. As for the pipe (gnarly rev), i've never cleaned the inside with anything caustic, but it was filled with water around the same time for a pressure washer bend/repair.
This was all done at the same time i was doing a top end, and i always leak test motors on the bench before they go back in the bike, so crank seals are definitely good.
I did a plug chop this evening. Looks like the ragged edge of too lean. What do you guys think?
It's worth mentioning that i had spooge half way down the silencer and dripping from the exhaust joint onto the swingarm after this evenings ride with the current jetting.

DAZZ- i will definitely keep my eye out for those! My KDX isn't going anywhere and i'd like to have extra parts like that around to keep it going for as long as possible.

jamiethegiraffe wrote: 06:58 pm Oct 11 2024 DAZZ- i will definitely keep my eye out for those! My KDX isn't going anywhere and i'd like to have extra parts like that around to keep it going for as long as possible.

Hoping to keep the price under 15 US dollars, will be available in 2 sizes as it's come to my attention that the factory size just does not work in hot humid environments, seems like standard size works for the US

jamiethegiraffe wrote: 06:57 pm Oct 11 2024 I did a plug chop this evening. Looks like the ragged edge of too lean. What do you guys think?

That definitely looks too lean, IMO/IME.

Hmm, since you have literally covered everything I can think of it is a conundrum. Have you tried a lower flashpoint oil? What ratio are you mixing at? Are you getting decent gas of at least 91 octane?

I thought it looked a lean as well. Probably will repeat the process this weekend with a 150mj and see if it's better. I think i have a 152 and 155 on hand to try out as well if need be.

SS- I'm mixing amsoil interceptor at 40:1 with 90 or 91 (cant remember) ethanol free fuel. I might try it at 50:1 (manufacturer suggested ratio) and see if it makes any difference.

if all else fails, i'll go back to CEK to confirm spoo is a needle issue for the way i ride. Maybe try running a flywheel weight to keep the wheel from spinning every time i look at the throttle with the CEK

Remember going from 40:1 to 50:1, with no other changes, is making the jetting richer. Less oil = more gasoline for the same amount of premix.

Just a question, do you ride lugging the engine a lot or are you more into riding in the power band?

Yes, thanks for the reminder.
I’ll go up a jet size and do a plug chop with some 50:1 to see if I’m in the ballpark.

I’m definitely lugging the engine a lot. I live in upstate NY and ride tight hardscrabble woods full of slippery roots and jagged rocks. Of course lugging a gear or two high for traction will result in lower combustion temps and more unburnt fuel = spooge.
So I know I’m a big part of the problem here. For what it’s worth I’m not trying to eliminate the drip, just hoping to reign it in a bit

Ah, yeah, that will exacerbate the problem for sure. Do you have an RB head by chance? If not, it can help in reducing spooge in the lugging situations.

Ya know, I was sold the bike with “RB carb and head”, but looking at that recent thread about ID’ing RB heads, I kinda don’t think mine is one. It may have been cut for squish at one point, but the dome looks more like stock from memory.

How did you do the plug chop? That color band looks pretty thick.

KDXGarage wrote: 03:11 pm Oct 12 2024 How did you do the plug chop? That color band looks pretty thick.

i thought it looked kinda thick as well for how light it is....
From what i've learned i believe i'm doing the chop test correctly:
Warm up the bike riding normally, then stop and swap for a brand new spark plug. As soon as the engine starts pin it at WOT and go through the gears on a slight uphill. Hold it at the top of 5th or 6th for 10-15 seconds, then immediately pull clutch in, hit the killswitch, and coast to a stop with the clutch in. Swap plugs again and ride back home to cut the threads off and have a look.

I did another chop today with a 150mj and 50:1 fuel. It's worth noting that the ground strap is reading 'too hot' on these WOT runs, but the same plug (BR7EIX) reads as perfect heat range (color change right in the middle) after a day of normal riding. It's also worth noting that the bike runs awesome and i'm not looking for more power or better throttle response. I'm just looking to get a safe baseline.

Today's plug in on the left- yesterday's plug on the right for comparison.
Whadya guys think? should i go another step richer on the main?

Just wondering, any reason for using a hotter #7 Iridium plug for plug chops? usually use and run the standard NGK BR8ES(B8ES)

Whoa, why are you using a 7 range plug? That's too hot of a plug for the KDX. You should be running an 8 and you don't really want to use the expensive plugs for plug chops. I highly suggest using standard NGK BR8ES plugs for plug chops and riding.