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Jetting with the Zook NECJ

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I switched to the Zook NECJ needle after a full rebuild (crank, replate, top end) this winter. I am trying to dial in the jetting, but I'm starting to think I may have another issue. Bike is an 03 yz250 almost entirely stock engine, stock squish (.072), and I'm at 600ft elevation riding in 40-50 degree temps currently. The bike is spooging like crazy from the exhaust and power valve puke tube, but seems to run well aside from a slight stutter at 1/16 throttle. Started with 45 pilot, NECJ 3rd clip, and a 172 main. Just swapped to a 42 pilot and 170 main, and it seems to smoke less, but still puking spooge. From my reading that jetting should be lean at my temps and elevation. I'm new to the Zook needle...any thoughts?

 

Edit: Running 91 non ethanol with Maxima Super M mixed at 32:1

Edited by Bricktop72
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25 minutes ago, LumberjackLloyd said:

Have you done a pressure test on the engine?

Honestly I have not. I did measure the amount of oil I removed from the transmission and it does not seem to be using any. 

Edited by Bricktop72

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I'd check your float height, re pack your silencer. I also have spooge running Maxima Super M but i looked it up and it has a pretty low flash point for trail riding I do. Other oils spooge the same. 

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8 minutes ago, Hands On said:

I'd check your float height, re pack your silencer. I also have spooge running Maxima Super M but i looked it up and it has a pretty low flash point for trail riding I do. Other oils spooge the same. 

Silencer was repacked after changing from initial jetting with the NECJ so within the last 2 hours. I did not have spooge problems at all with this exact oil and ratio with the stock needle 2nd clip, 175 main, and 48 pilot.

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Try the second clip and go up on the main and pilot. I would go with a 50 pilot for your cold weather and low elevation and a 178 or 175 main for starters with NECJ #2.  If NECJ #2 is too lean, get a half clip richer NEDJ and try it in the second clip.

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10 hours ago, Bricktop72 said:

Bike is an 03 yz250 almost entirely stock engine, stock squish (.072), and I'm at 600ft elevation riding in 40-50 degree temps currently. The bike is spooging like crazy from the exhaust and power valve puke tube, but seems to run well aside from a slight stutter at 1/16 throttle. Started with 45 pilot, NECJ 3rd clip, and a 172 main. Just swapped to a 42 pilot and 170 main, and it seems to smoke less, but still puking spooge. From my reading that jetting should be lean at my temps and elevation. I'm new to the Zook needle...any thoughts?

If your motor is healthy (top end, reeds, PV function, pipe and air filter), then with 072 squish at below 2000ft and cool-ish temps your jetting doesn't seem super rich.

P=45 N=NECJ-3 and M=170 should be close.

After going to P=42 and M=170 how does it run? Ignoring spooge, does it run lean or rich at 1/4 1/2 and WOT?

If it runs great then maybe the old spooge oil is built up inside the PV cavity and the whole pipe system.

If you are riding a lot at 3/4 to wide open throttle then try a smaller main.

The zook needles do not cause spooge. The opposite after you find the correct settings, because the zook needles let you get your preferred air/fuel ratio at all throttle openings.  If I go a clip too rich on a zook needle then I notice a massive power loss well before I notice the extra spooge.

After a ride at WOT with a new plug, what does that plug look like?  You might be able to see if it's a rich or is the plug fouling with partly burned transmission oil (right side crank seal gone).

 

 

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4 hours ago, numroe said:

If your motor is healthy (top end, reeds, PV function, pipe and air filter), then with 072 squish at below 2000ft and cool-ish temps your jetting doesn't seem super rich.

P=45 N=NECJ-3 and M=170 should be close.

After going to P=42 and M=170 how does it run? Ignoring spooge, does it run lean or rich at 1/4 1/2 and WOT?

If it runs great then maybe the old spooge oil is built up inside the PV cavity and the whole pipe system.

If you are riding a lot at 3/4 to wide open throttle then try a smaller main.

The zook needles do not cause spooge. The opposite after you find the correct settings, because the zook needles let you get your preferred air/fuel ratio at all throttle openings.  If I go a clip too rich on a zook needle then I notice a massive power loss well before I notice the extra spooge.

After a ride at WOT with a new plug, what does that plug look like?  You might be able to see if it's a rich or is the plug fouling with partly burned transmission oil (right side crank seal gone).

 

 

Engine was totally fresh 8 hours ago. Runs pretty good with the current jetting. I have been happy with how the Zook needle improved the mid range throttle. I guess I'm not very sensitive to feeling changes in jetting like some guys. 

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I can't emphasize enough how important it is to do a pressure test. It has caught many issues before I even started the bike; or finished assembly.

I have seen leaking crank seals that don't leak enough for a noticeable difference in oil level.

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Stock jetting should be about right for sea level in North America. NECJ #2 would be closer to your stock N3EJ #2. NECJ #3 would be closer to N3EJ #3 . I still think you might be rich on the needle. The needle is responsible primarily for the 1/4 to 3/4 throttle range where  most riding takes place. If you are rich on the clip that is likely to be your spooge problem. You should repack your silencer too. If its a crank seal leak, your bike will seem rich no matter what because you will be burning transmission fluid as well. You might want to look into whether or not the seal is leaking. If your transmission fluid is low when you change it , this should be a telltale sign.  I bet your silencer is full of spooge. With it being an 03, when was the last time it was repacked? In my opinion you are lean on the pilot and main. I also would be willing to bet at your temps and elevation your bike revs to the moon on startup with the choke on with that crazy small pilot until it warms up. It might be fine in Australia if the humidity is higher but a 40 or 42 pilot sounds very lean for sea level and less than 60 Fahrenheit or 15 Celsius.

Edited by mcgradybrandt

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SET YOUR SQUISH.  

 

Also, how do the reeds seal?  ANY leakage here will make it run seemingly rich and be a little low on power.

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2 hours ago, mcgradybrandt said:

Stock jetting should be about right for sea level in North America. NECJ #2 would be closer to your stock N3EJ #2. NECJ #3 would be closer to N3EJ #3 . I still think you might be rich on the needle. The needle is responsible primarily for the 1/4 to 3/4 throttle range where  most riding takes place. If you are rich on the clip that is likely to be your spooge problem. You should repack your silencer too. If its a crank seal leak, your bike will seem rich no matter what because you will be burning transmission fluid as well. You might want to look into whether or not the seal is leaking. If your transmission fluid is low when you change it , this should be a telltale sign.  I bet your silencer is full of spooge. With it being an 03, when was the last time it was repacked? In my opinion you are lean on the pilot and main. I also would be willing to bet at your temps and elevation your bike revs to the moon on startup with the choke on with that crazy small pilot until it warms up. It might be fine in Australia if the humidity is higher but a 40 or 42 pilot sounds very lean for sea level and less than 60 Fahrenheit or 15 Celsius.

 

14 hours ago, Bricktop72 said:

Silencer was repacked after changing from initial jetting with the NECJ so within the last 2 hours. I did not have spooge problems at all with this exact oil and ratio with the stock needle 2nd clip, 175 main, and 48 pilot.

 

5 hours ago, Bricktop72 said:

Engine was totally fresh 8 hours ago. Runs pretty good with the current jetting. I have been happy with how the Zook needle improved the mid range throttle. I guess I'm not very sensitive to feeling changes in jetting like some guys. 

 

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Reeds are new and sealed tight, silencer has less than 2 hours on a repack, engine has 8 hours since total rebuild (crank, top end, all bearings, seals, and cylinder replate). Have already measured the squish with solder and will send the head out when I can. I haven't had any problems with how it's running, just trying to remedy the spooge. The only variable is the NECJ needle. I might just go back to the stock needle and jetting to see if that solves it. 

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TRY NECJ #2, SERIOUSLY! One clip position can make a HUGE difference. And if it idles too high, turn your air screw in a 1/2 turn or so or go to a 50 pilot.

Edited by mcgradybrandt

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10 minutes ago, mcgradybrandt said:

Any reason why you haven't tried :175 main, NECJ #2, 48 pilot?

Yea because everywhere I've read says that NECJ clip 2 is too lean for my temps and elevation. Also with a stutter/burble at 1/16 to 1/8  throtttle it sounds like my 45 pilot was rich. 

 

Here is a video with the 172 main NECJ clip 3 and 45 pilot. 

 

 

 

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15 minutes ago, mcgradybrandt said:

TRY NECJ #2, SERIOUSLY! One clip position can make a HUGE difference. And if it idles too high, turn your air screw in a 1/2 turn or so or go to a 50 pilot.

I will try clip 2 but the 50 pilot is just absurd. The 50 pilot was too rich with the stock needle above 60 degrees, I ran a 48 almost all year.

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