STIC Metering block Jetting

If it is bogging, I would try a 50 pj and start around 3 turns. Sounds like the rest is good.

Thanks,
The guy using the N3EJ in the Honda , is the the last generation power valves engine, or in an HPP engine. You would have a much better chance in an HPP engine.
Yotam, out of the needles you have listed I would probably try the NOZG 1st. Put it in the #3 clip with a 48 pilot and a 190 main to start. It’s going to run a little rough down and it still going to have some oih though until you get the corrrect needle.

Did you ride with any of these? The whack test doesn't tell all that much.

Going by what you have written, j would be more inclined to use the 3j needle. Even in the 4th or 5th clip position. It's quite possible you need to try other needles however. Maybe try a couple that Digger mentioned.

How did the plug look respectively?

What slide are you using?

I may have missed it somewhere in this thread, but did you switch to the .115 needle jet tube when you went to the 38mm? Or are you still running the .114?

Your application may require the richer .115 tube if you find that you can't get rid of the 1/2 throttle leanness. At a certain point, the needle jet tube becomes the bottle neck in the system, depending on what you are doing. For example: on my 300 with the 38mm carb, the .114 works perfectly and the .115 tube is way too rich, no matter what needle I ran. When I moved to the 40mm carb, it required the larger .115 needle jet tube because the larger bore is allowing more air into the engine. The .114 needle jet tube with the 40mm bore was too lean, no matter what I did.

While a 125 and a 300 jet quite a bit differently because the 125 has a much weaker signal from the engine to the carb than the 300 does, the principal is still the same in that you went from a 36mm carburetor to a larger 38mm carburetor. You could continue to try different needles and it is certainly possible that you may find one that provides correct fueling throughout the RPM range, but you may also find that you might always be lean somewhere no matter what needle you try because the .114 needle jet tube could be the bottle neck. If the N3EJ needle felt too lean everywhere, it may acutally work perfect with the .115 needle jet. Just some food for thought.

If you are going to keep trying with the .114 needle jet tube, you may want to look into Suzuki needles as well. In my experience, they seem to have a much richer taper and tip than the Yamaha and JD series of needles I have experimented with. George does sell .115 needle jet tubes individually, if you decide to go that route. I would not give up on the STIC. It is well worth the effort once it is dialed.

I would also see if Derek Harris from HP Race Development will chime in on this conversation. I believe he has tested the STIC on 125's and may be able to provide more insight for your specific application.

I would try that same jetting, but with the .115 Needle Jet tube.

It is very simple to replace. You can order one from George. Just tell him you want a .115 Needle Jet tube.

Instructions on how to change it out:
https://youtu.be/FCyW6Ads2kA

Why would a .114 be sent knowing the application?

Curious mostly as I would think he'd know, but CSAR is more than likely spot on since He has had extensive testing.

My assumption would be that the original application was for a 36mm carb. I can't say for sure, though.

Yotam; Ok here it is; the 38 mm carburetor should have the 115 tube, 195 main, 52 pilot jet, # 6 slide. in this application using the #6 slide is very important. George STIC Fuel Systems

Disregard

Have/can you use a PWM carb with the STIC meter block?

The PWK STIC Block will be avail early 2019. George

What is the consensus on the stic block on a cr139cc hpp engine?
I've got the 114 tube, 48pj, 2 1/2 out, 1369n middle clip and 185 main. That's how Derek sent it.
Sea level mild weather. Runs good in the middle throttle but no good elsewhere. Lean bog cracking the throttle fast out of tight corners or race starts just over the gate as it loads. Doesn't like full throttle (lean) but can handle 7/8 throttle nicely.
It sounds the 115 tube is the go?
Or 190 main, 52pj?

Call me at 715-479-7822; the bike is jetted incorrectly and it needs the new 113A tube; send carburetor to me; will install new block no charge. George

Yotam the bike is not even close to being jetted correctly; call me at 715-479-7822 or email directly at stic@frontier.com. George

STIC instructions with JD Jetting for 125cc through 500cc (updated)

Oil ratio (rich-lean) in jetting symptoms.

New: Your oil ratio to fuel will affect jetting; typically, the oil ratio range should be 40:1; more oil less fuel (leaner). Less oil (60:1) more fuel; this will make the carburetor rich; check with your buddies and engine builders. It always better to be safe; however, there are many that run synthetics at +60:1.

For maximum performance; the new JD Jetting kit for the STIC metering Block is highly recommended. The STIC tuning kit for the STIC Metering block is available from STIC headquarters (vortex@sticfuel.us); MB*DBB-Performance; KPR Racing, Harris performance (Derek); TOKYO Off-Road, and JD Jetting. This STIC kit has been engineered by the founder of JD Jetting James; take his advice. The kit includes the following: main jets, (180 to 200), pilot jet #50, new longer stronger spring; two needles; Red II-II; leaner top, Blue IIII, richer top) — both have a smaller tapered tip (approx. .055”).

STIC needle information
STIC needle tuning options; the preferred options are the JD Red (STIC) II-II — JD Blue STIC (IIII) and the N3EJ.
The STIC production tubes are produced to the following standards 2.870mm (aka .113A) and the 2.900mm (aka .114A”). Larger Alcohol sizes are available. Here are the needles that are available. These measurements are approximate.
Keihin Stock, NVZA: .105” Tip: .073”
JD Blue: IIII (STIC) .1062” Tip: .055”
JD red: II-II (STIC) .1072” Tip: .055”
JD red: II .1065 Tip: .073”
N3EJ: Yamaha .1075 Tip: .075”
Suzuki NEDK: .1082 Tip: .055

For the last seven years the STIC has been field and dyno-tested all over the world; ranging from sea level to +9,000 feet. Dramatic changes in temperature and elevation do not require any major adjustments. If you have an earlier model STIC; there is a new free STIC Tube .113A (2.870 mm) upgrade; you must send the entire block and tube to STIC Headquarters. Send the STIC metering block and tube directly to STIC Headquarters for free tube upgrade. If you want everything checked including proper float level; send the entire carburetor with slide to STIC headquarters (no charge). There is also a #7 STIC Block for leaner performance and for higher altitudes.

The STIC will work with jets, ranging from 178 to 220; the preferred setting for maximum performance will be in the 190 to 210 range; this applies to the 125 to 500cc engines. The pilot jet must be at the +50 range with the 50 being the best overall (this is part of the STIC power jet system). The air screw must be in the range of 2 to 4 turns out. New Keihin STIC carburetors from STIC have the new longer (+.100”), stronger piano-steel spring; so, no worry about the air screw working loose. These new springs are available from TOKYO, Harris, and STIC factory. If STIC adjustments are needed; first work with the needle clip position, top clip will make the mixture leaner, the bottom clip will make it richer. Adjust accordingly to your preference. It is my estimation that one must use a needle with the top straight section being at least. +. 106" in diameter; this starts with the JD red II-II (.1072”), JD Blue IIII (.1062”), the Yamaha N3EJ at .1075" and the Suzuki NEDK needle is +. 108."


STIC tuning procedure;

Be sure to check for a clean air filter, check the reed cage for any petal wear. Check the float needle valve for wear (STIC recommends changing the float needle once a year); set the float according to specs (there are several great videos). Do not run the vent lines into the airbox; this will cause the carburetor to run lean. Do not run the fuel bowl overflow vent tube in an upward position; it must be pointed down; if you run the vent lines upward make sure they are pointed down at their ends.

Even though others may disagree; the engine should be warm before attempting any STIC jetting decisions. Believe it or not; oil and fuel can and do accumulate in the case, transfers, and combustion chamber. When installing the STIC metering system; and before making final jetting selections; here is my advice; install a new spark plug and run the STIC for at least 30 minutes at various speeds to help clear the case, cylinder, head combustion area, and the engine of any raw fuel left from the previous carburetor.

Before making any major jetting changes; first, experiment with moving the needle up and down; the top clip (#1) is leaner; the bottom clip (#5) is richer. When you feel you have a good needle position selection and having the air screw at the recommended settings; adjust the front air screw in small increments; not going below 2 turns. A larger air screw setting air-corrects the larger pilot jet and allows more air to go into the main jet power inlet. Going to a larger slide will also correct a low-end richness. The standard aftermarket Keihin Shorty comes with a 6.5 slide; JD Jetting has the larger #7 and #8 slides.

In summary, do not be lured into using a smaller pilot and main jet; the main and pilot are designed to do certain things in harmony, and they are heavily air corrected. Even though the STIC will run with smaller jets, there is a substantial increase in power by using the larger jets. The STIC is heavily emulsified with air and other forces; using the smaller main jet will tempt you into making corrections in the wrong manner. The STIC has a multiplying (increasing) power system; increasing fuel curve, and instant acceleration.

Greater Power with the STIC:

Jetting your engine for maximum performance with the STIC depends on modifications, pipes, ignition type, temperatures, atmospheric pressures. Fuel types such as oxygenated fuels may require larger main and pilot jets; do not be afraid to experiment with larger main and pilot jets while using conventional fuels as well as oxygenated fuels. When using oxygenated fuels consider using the stock Keihin needles in the lower clips. We find the STIC metering system sees no loss in horsepower and torque with less compression and less timing (2o less). Due to the fact the STIC system will allow the engine to have expanded over-rev; STIC recommends having a deck clearance of +.050” — increasing the deck clearance to .070” shows no loss of power. Due to the overrev feature of the STIC; consider using a longer pipe or head spacer of ¼ — ½ and you will have the best of both worlds; greater torque and overrev.


Oil ratio (rich-lean) in jetting indications.

Your oil ratio to fuel will affect jetting; typically, the oil ratio range should be 40:1; more oil less fuel (leaner). Less oil (60:1) will make the carburetor rich; check with your buddies and engine builders. It always better to be safe; however, there are many that run synthetics at 60:1.

Engines 125/200;

As remarkable as it may seem; the 125/200cc engines will jet with a #200 main jet, #50 pilot with the JD Red STIC (II-II) needle; and of course, one may jet as needed fist experimenting with the larger jets.

Engines 300/500;

When using the 113A tube; the new STIC/JD blue needle (IIII) will give you similar flows equivalent to the 114 tubes. It is highly recommended that you utilize the new STIC JD Red (II-II) needle; this has the smaller .055” tip. For maximum flow select the lower clips #4 an #5 to determine if you need a larger main jet. It is critical to run the larger pilot jets in the 52/58 range as this provides more fuel for the STIC power circuit. The STIC is an entirely new process and requires learning new things; feel free to contact STIC headquarters for any assistance and upgrades; glad to help and answer any questions. Enjoy

Keihin 38mm or the 36mm?

STIC recommends the Keihin 38mm with STIC. The reason some manufactures use the 36mm is due to the stock carburetors' inability to accelerate with the larger 38mm; thus, they use the smaller bore to increase velocity and a greater shearing pressure drop at the tube outlet. This is not the case when using the 38/40mm STIC equipped metering system; the 38/40mm with STIC will develop greater horsepower as the STIC has a very aggressive acceleration feature along with a progressive fuel enrichment. There is no need for wings or power jets while using the STIC; in fact, they are discouraged. The STIC constantly senses torque demand and regulates the fuel delivery and vaporization levels increasing its output based on sensing changes in the environment (landscape changes) as well as rider demand.

Other STIC options;

We have the STIC metering blocks for the Keihin A/S screw-top (90mm long) and the Keihin A/S shorty (75mm long). Options: we also straight and taper bore the 38mm carburetor to 40mm; we modify the carburetor top for more cable free play, and we make all necessary adjustments including float level and jetting for specific applications. Please call anytime for tuning advice and product availability.

STIC Fuel Systems vortex@sticfuel.us
P.O. Box 1119Eagle River, Wisconsin 54521 Phone: 715-479-7822 (9:00am to 9:00pm central)