More on spoo....

[jamiethegiraffe]

I ran a BR8EG for a long time, but thought I’d try a 7 for all the tight woods riding I do. According to the ground strap, 7 is right and 8 is too cold when I’m riding normally.

However, i agree that I should probably be using an 8 for plug chops. The only reason I’m using iridium 7 plugs is because I got half dozen for $20.

Any thoughts about the soot ring? Should I go richer yet? Or is this all kinda moot because of the 7 range plug?

I feel like I’m learning a lot here and really appreciate you guys chiming in with your experience and opinions.

[SS109]

The soot ring looks ok to me considering the heat range. Would like to see what it looks like on a BR8ES.

As to the heat range, we've all learned over the years that an 8 range plug is good for literally any condition, from hike-a-bike to wide open desert, you could ever encounter on your KDX provided the jetting is good. I literally change my plug (BR8ES) once a year just because I feel I should and not because I actually need to.

[jamiethegiraffe]

I’m sold, i’ll go back to an 8 tomorrow and do another chop. Never had any fouling issues with an 8 before, but had been told that a 7 might help clean up the spooge for slower woods riding.
Thanks SS!

I’ll post back here if I make some headway with my filthy muffler. Want to try CEK again once I know the main jet is correctly sized.

[KDXGarage]

plug chop technique sounds perfect to me

I would not run a 7 for a plug chop. I can't imagine needing to run a 7 around here for local riding. The pre-1995 KDX's actually came with 9's, but I switched to 8's and it was SO MUCH BETTER.

[jamiethegiraffe]

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.

Just a follow up: I looked through some old photos a bit this morning and found a nice clear pic of my cylinder head from last summer. Comparing my head to the photos chuck78 posted recently, i'd say i think this IS an RB modded head after all. Whadya'll think?

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Follow up plug chop with BR8ES coming soon...

[kdxdazz]

Yes that's an RB head, you can tell by the machining, sharp transition and the head has been milled

Hotter plug is not for clearing up spooge it's for making the plug less likely to foul under loading conditions at lower RPM

I've never understood the value of plug chops myself, as you stated most of your riding is slow technical, this is all pilot jet, needle, emulsion tube, air screw

I was out testing jetting yesterday, a good test is to ride at idle in 2nd , open the throttle quickly and learn to understand the difference between a rich bog and lean bog, if your pilot jet is set correctly any bog is best corrected with straight diameter, CEK is very rich at 2.695 straight diameter, I'm using 2.75 but I am at altitude and near the equator , also using E10 to lean it out even further

[jamiethegiraffe]

Great ride and some interesting findings today-
I switched to a BR8EG plug and ran 50:1 mix with a 38pj and 150mj air screw at 1.5 DEK on #2. Amsoil Interceptor & 91 ethanol free.
Ambient temps were 60 degrees F with low humidity.
I replaced the exhaust joint gasket with one of the new style KTM 300 silicone sleeves with zip ties in the grooves to seal it up.
This all fairly typical for me besides the 50:1 and new exhaust joint sleeve. As usual, the bike ran awesome, but the wild part was that the tail pipe didn't even have a dribble after an hour of tight woods!

I'm not sure what i got right, but i hope it lasts!
Haven't done a follow up plug chop with the 8 plug, but hope to do so this weekend.

[jamiethegiraffe]

After some more riding with the aforementioned setup, I thought it worth a post that some days there’s barely a dribble from the muffler, and some days it has a drip running half way down the turbine core II. I still think the situation is much improved with a 50:1 mix.

Here’s the latest plug chop with a BR8ES plug (on the right, BR7EIX on the left for reference). Same setup on both plugs with about 15°F warmer ambient temps for the 8 range plug on the right.

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I’m also including a pic of the unchopped BR8EG I’ve been running on the trails. Hopefully this info will all be helpful to someone combatting KDX spooge in the future

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[KDXGarage]

Wow. That looks too lean to me.

In general riding, how often are you revving the heck out of it?

Did you take the pipe off and clean it before starting the plug chops and jetting? If it was rich for a long time, the oil was still in the pipe and spark arrestor.

[SS109]

Yes, very lean.

[jamiethegiraffe]

Wow. That looks too lean to me.

In general riding, how often are you revving the heck out of it?

Did you take the pipe off and clean it before starting the plug chops and jetting? If it was rich for a long time, the oil was still in the pipe and spark arrestor.

I did not remove the expansion chamber before this process. I do a fair amount of slow wheelies & pivots, so it should help evacuate some residual spooge. I did have the silencer off the other day to install the exhaust joint sleeve- nothing was dripping out of it.
For what it’s worth, I’ve been running this exact jetting or something very similar to the 40,150 setup the RB carb comes with for quite a while now- the main thing that I’ve changed recently is using 50:1 fuel instead of 40:1.

I don’t rev the bike to the moon very often, but it was hard on the pipe heading out to the fire roads for a plug chop just before I snapped that pic of the plug I’ve been running. I think that plug has about 2 or 3 hours on it- mostly in the woods


You guys think it’s too lean despite the full ring of black around the base? I could fatten up the main another step or try raising the needle a notch. I’m hesitant to mess with the pilot as the bike starts well hot or cold, idles perfectly and runs crisp in that throttle range.

[jamiethegiraffe]

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Here’s a pic of both sides of the most recent plug chop with decent lighting

[jamiethegiraffe]

My jetting and plug chop saga continues on, but I just wanted to address the topic of this thread once more for posterity and say that despite increasing my main jet size incrementally, my spooge production has dropped off dramatically since switching to a 50:1 mix. So yes, jetting is very important, but i couldnt lean the fueling lean enough to stop the spoo. Less oil was the key for me. I believe the 50:1 mix is less heavy than the 40:1 mix and therefore atomizes better resulting in a more complete burn.

I'm not advocating that anyone run less oil, but if you're struggling with a silencer that looks like an environmental disaster, it could be worth trying a different mix ratio and then re-jet accordingly

[kdxdazz]

One of the things with oil ratios is it's RPM dependant, my kdx220sr has an oil pump and from memory that is 100:1 at idle and building from there, trails bikes run 70:1 as nearly all their riding is idle and low RPM, if most of your riding is low RPM then 50:1 is plenty
I may have mentioned this previously but many people seem obsessed with running expensive oil designed for high RPM racing yet their riding is not high RPM, it doesn't burn cleanly and doesn't mix well with gasoline, I stopped using high end oil years ago and now use a low smoke formula for scooters, there is now zero smoke that I can see but night time in the city with a headlight shining behind me I can see smoke but I think most of that is my jetting is still off

[KDXGarage]

I split this off from the 2005 thread, which is why it does not have the same exact location as before.

Thank you.

[Houston TX KDX]

New member here, my inquiry is aimed towards KDXDAZZ, on your kdx220sr, I'm not certain but I believe your oil pump could be RPM dependent and throttle position dependent, as some oil pumps share a connection to the throttle cable via a piggyback style cable/split cable system so that oil dispensing volume is dependent on RPM and throttle positioning.

[kdxdazz]

New member here, my inquiry is aimed towards KDXDAZZ, on your kdx220sr, I'm not certain but I believe your oil pump could be RPM dependent and throttle position dependent, as some oil pumps share a connection to the throttle cable via a piggyback style cable/split cable system so that oil dispensing volume is dependent on RPM and throttle positioning.

Correct, it's just a simple throttle cable that has a double split at the half way point to connect the oil pump
Oil pump also has timing marks
I seem to be using quite a bit of 2 stroke oil even though my timing marks are correct, will test and investigate more, only recently completed a full engine rebuild
Was running very rich off if idle. No needles available here so experimented with epoxy the straight diameter, went from 2.45 to 2.48. hopefully test this week

[billie_morini]

What he say, I agree:

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.

[jamiethegiraffe]

Beating a dead horse on an older thread here, but i recently made a significant discovery regarding my spooge production machine and thought it important to note for posterity.

A while back i switched to 50:1, and that seemed to help the issue, but it was hardly a silver bullet. What i've discovered recently thanks to KDXdazz's hard work is that my carb's emulsion tube was heavily worn. The needle sliding into it was the proverbial "hotdog in a hallway" causing an extremely rich condition at idle and low throttle positions. It ran well with a 38pj and needle clip on #2, but the spooge seemed unstoppable and i wondered why my KDX preferred so much leaner of a setting than many others have noted.

Now that i've replaced this tube with a reproduction from KDXdazz, the wave of oil from my muffler has reduced to barely a dribble. I'm running a richer jet set and needle position that jives more closely with what others have noted as successful on their motors. I think i'm also going back to a 40:1 premix. The bike feels great and will cruise smoothly at a steady low throttle angle- something it has never been capable of as long as i've owned the bike.
Hope this helps someone in the future!