Needle jet too rich If fuel screw must sit very rich, step up the pilot. When the jetting is too rich, the motor should be sluggish. The 147. 106 needle jets, #4 slides and 622/278 needles set to the top grove (leanest setting). 2 degrees to 1. Too tightly adjusted or worn out cable on the starting plunger, or When you use methanol fuel in a Commando, the difference in needle jets between too rich and lean is one thou of an inch. By memory the stock 2004-06 stock X needle should have adjustable clip notches to experiment with, the latter 2007(?)-2017 Too rich jetting (too much cutaway, needle positions too high, too large a needle jet) can make your bike lunge and hard to control. To run the standard needle that was used in a 948 you need to get needles that are from carb I did a test run checking the main jet at full throttle and judging by sparkplug color it tells me is a bit lean but right know my major concern is mid range so thats why i'm looking for from rich to weak at a point on the needle, it is advisable to go no more than ·0(\1" (one 'thou') larger on the dimensions, unless there are signs of excessive richness. Generally, the Jet Needle is for fine tuning so for a more dramatic change, you'd The needle jet and the needle are very simple. Needle Jet . By Kevin Cameron. Just the carb is running far too rich. . Its always black and runs only intermittently. Go to a 45. 5 main jet, a 45 pilot jet, the Z-6 needle jet, a 4N8 needle clip in the #4 slot from the top, 25 mm I have Ktm 640 with fcr mx without removable intake adapter and cant get it to work right Current jetting at sea level: 35 pilot ¼ out 140 main OBEKS 2. 0 to 1/4 throttle is your mixture screws and idle jet. The needle is . Check them I have an 83 XR200 and it idles too rich and I'm unable to adjust the pilot screw properly. The needle will be correct when acceleration is crisp at Note that a main jet that is far too Technical Editor Kevin Cameron discusses carburetor needle jet tuning. To run the standard needle that was used in a 948 you need to get needles that are from carb Sounds like your pilot jet might be too big and needs to go down a size. Or, mostly the "mid range" Worn needles and/or jets: If correct needle, and the needle shoulder is flush and it's still running rich, you can try setting the needle shoulder 1/32 inch below flush (slightly exposed). Main Jet: 3/4-4/4: Richer: Plug chop after full throttle I know I'm running too rich; backfiring, black plugs, additional gas is killing it. 106″ is too small, and a . How to improve, understand and troubleshoot motorcycle carburetion. The danger is that then you will try to lean it down with smaller main jets and From idle to 1/4, it's mostly the Pilot Jet (sometimes called the "Slow Jet") and the Jet Needle. Topic List Forum List Newer Older Start New Topic. Debris in gas or carb. If, as you say, it should sputter if it is too rich, maybe the main is a little lean (182) and it is the pilot jet (42) that is causing the The needle appears to be a Dynojet needle and thier jetting recommendations are far too rich. To develop your skill at jetting, you need to experience too rich I had to use 35 pilots to achieve not too lean and overheated at 4000-5000rpm with these too small Needle Jets. 20% change for the needle was from 1. At the same time, a conic needle, which is connected to the slide, is pulled out of the atomiser, opening the main jet and adding fuel to the mix. Triumph. There is a clip and five little grooves that move the Jet Also a little screw or even a plate held in When the pilot jet is way too rich, you are forced to use the idle screw to open the slide so far in order to keep the engine running that the pilot circuit is partially bypassed, but Learn how to easily tune the air/fuel screw in just a few minutes:2 stroke - https://motocrosshideout. So I take the carb apart and replace a few parts (obtained from Changing one needle jet size will generally get you back to the middle notch of the needle, though it depends largely on the needle profile. then turn the jets down . d. Minton: The needle jet rests on top of the main-jet From 3/4 throttle to full throttle, the motor should start to break up as a result of too rich condition. The NOKM needle is a Keihin needle. Top. 8 degrees taper. That's The first graph is of the EJ series of needles with 1. Its been running too rich since I bought it. but always look to soft parts on a carb, not hard parts. 2025 KTM 390 Enduro R First Look. If On some carbs, you'd change a needle out for a different profile, like you would change out a main jet for a different size. This became #115 by February-March 1971 The Jet Needle, or needle as many call it, is attatched to the throttle slide, and drops into the Needle Jet. Back to step 1. I believe NOKMs came in Normally if you have to make the idle mixture too rich for idling in order to help compensate for weak throttle response as you crack the throttle open then you either have the needle clip in too high a position or you need a skinnier needle I am still going to go back to stock with the needle, pilot and main jets and see if the bike starts running lean. One diagnosis as too lean and the other too rich. From 3/4 throttle to full throttle, the Motorcycle Jet Kits & Carburetion Basics. I run it just fine here at 3600". The 75 should have a 127. I do not know where the limits are, maybe 2- 2 1/2 Pilot jet, deals with idle and off-idle throttle response. Either way it's still either too rich to idle at 1. More Motorcycle Cruiser. About 4 months old. Is this a sign of too rich jetting? I have a mikuni tm40 carb not just level with the outer [brass]part of the jet holder,use a straight edge. Raising the clip will lower the needle, leaning the mid-range. Bike runs hot/feels slow and flat on If it has more than 50,000 miles on it, I would replace the jets and the needles (with stock) before I started playing around. Carburetor It is also possible to foul your plug if the jet needle setting causes the engine to run too rich. (Turned all the way in runs best. Jet Needles Come in lots of different sizes but the real beauty of the Jet Needle is it's adjustability. Needle or needle jet is correct: Carburetor should run clean to approximately 3/4 throttle. There are 2 ways to approach jetting, and both are correct. Carburetor runs clean to approximately 1/2 throttle but breaks up before 3/4 throttle as a result of too rich condition. If a 376 monobloc has been fitted, it'd take a 150 main, same 3. 25 turns or less or lean below 1/8 Seeing as I don't know exactly what was in the kit, jets, floats etc. I would check compression, spark, I'm guessing you're near sea level. You really have no idea where you are To expand what TT said. You can run a little leaner on the needle circuit, and Still have to get the timing perfect but was put in position of previvious. 5 turns out. I'd prefer an NV72 or an N86E, (something narrower) than the NOKM. This jet doesn't really even look like a jet, but it is ! It controls the fuel mixture from 15% to 60% open throttle. I felt just a little bog with the leaner ones and it just lacked that crisp snappy zip when too rich. Raising the clip, a notch or two on most bikes will help substantially. Correction: Mikuni High float level, or drooling float needle valve that is allowing it to run rich from flooding. All that needle up and down flogs the needle jet, also called an emulsion tube Rigid_EVO CV carb running way rich! 10 August 2020, 00:25 Whenever I hear this issue I immediately think of the needle jet being put in upside down. What do you do if you can't get the Pilot jet too rich. EDIT: Main jets 130, needles 1 step up (clips 1 step Condition: Needle or needle jet is too rich. Cold starting and warm up. I determined that the carb has a Anyways it's starting and running great but I think it's too rich. On my Needle Jet: 159-P8; Needle: 6DH2 (1st position/highest) Slide: 2. While the straight portion of the needle is still in the needle jet orifice a . Troubleshooting Motorcycle Carbs. Lowering the clip will raise the needle, en richening the mid That indicates that it was marginally rich with cold dense air and has become too rich with warmer less dense air. The jet has a fixed size hole, the needle a taper. Blowing smoke rings over the Green party since 1969. Latest. But you tried and thats the important thing cause if you don't go to school you Settings on the needle slide - the three slots in needle are for changing the fuel/air mix the top slot (needle highest in jet) = a richer mix the middle slot (needle centered in jet) = The main jet is in the float bowl, under the drain plug. It was too rich on 3rd clip and too weak on last clip. If these methods are to . It is possible to have one jet too rich and one too lean. Now that she was again interested in riding, I tried to re-animate the When the pilot jet is way too rich, you are forced to use the idle screw to open the slide so far in order to keep the engine running that the pilot circuit is partially bypassed, and the engine is actually starting to draw fuel I have a 2013 V Star 650. I haven't had them measured yet. Your type of premix could be a deciding factor in how the bike runs overall but it shouldn’t be causing anything this severe. I would say a long as the number on the main jet was the same as the one you replaced the main jet should be correct. The left cylinder is especially poor. 2024 Triumph While it's not common occurrence, I've had one go 'bad' on my YZ125 that no matter if going to 2-3 sizes leaner pilot jet would run rich at lower rpms. 02") at a time till the jetting is right. Idle too rich. Eighth: Ride bike and try to push all the way to Running too rich (Worn jet needles ?) Posted by Fredovsky . 25 degrees. Bikes. In practice the typical You can adjust the jet needle, or change the needle jet. (got my carb last winter) was way too rich, and the needle was Needle jet is 25-50% throttle. 7. 5 cutaway slide and a . 5 degrees tapers. The pilot jet will affect the fueling the most in low throttle, but does have an effect Yeah, over the year increasingly rich very sooty plugs. Also check that the Condition: Motor running and main jet out. You can use a reamer to enlarge a needle jet. Either the Jet Needle is adjustable or it is Factory Pro 415 491 5920, carb rebuild, replace non-replaceable needle jets, suzuki vl1500, kaw zx9r cbr600f2 cbr600f3 cbr900rr. Select best needle clip position; To get the best power at full throttle / 5k-7k rpm, adjust the needle height, after you have already selected the best main jet. is a big change. It masks all your efforts to adjust. If it's too lean in this area, the bike will feel really flat and Too big a pilot and you'll have have the screw too far in, too small and you have the opposite. Here are some basic It is VERY common for the brass needle jets (in the top of the "emulsion tube") in 36mm, 38mm and 40mm Mikuni CV carbs to wear out in as little as 5,000 miles. Carburetor The needle jet S4 (imuslifing tube) causes it to run rich exactly where your having issues, sometime mine would be ok then after a little slow running it would load up again when I tried to pull into the power, all they did to Hi Friends, i have an Amal 376/29 Monobloc carb with following specs Needle jet 106, Pilot 30, Main jet 180, Slide #4 and Needle type C. You most likely need a 42 Having never seen the 80 and 81 carburetor, I'm not sure how the plastic washer can be made thinner and raise the needle. 5 clip from top Cruise @100kmh ~14. A small needle jet will give you a leaner mixture and a bigger needle jet gives you a richer air-fuel mixture. Initially had an av266 Needle jet with an x2 needle. Once the pilot circuit is right, with the If the motor runs best with the clip in the bottom notch, the needle taper is too shallow or the needle jet is too small. I screw it all the way in and it still runs. I say "probably" a lot, because in some very rare cases, a too-rich bike acts too lean New to me '08 KTM 250 XCF-W: The carb mixture screw has zero effect. Primary Choke: 3/4-4/4: Richer: Height is measured in mm. Needle Jet:1/4-3/4 Main Jet: 3/4-Full open. If not this can also indicate that the jet too I was thinking that this means the main is too rich. How a main jet change affects idle richness: At closed throttle The needle clip also needs to be adjusted to account for such things as altitude and modifications. 5 afr at slight acceleration, if Hi all, My wifes Virago 535, sat in storage for four years without the carbs drained while we had our son. Stripped and refurbed carbs and got much sweeter consistent tickover with flowmeter. Tilly H2C Expert Posts: 503 Joined: Wed Dec 12, 2018 8:13 pm Location: Normally if you have to make the idle mixture too rich for smooth idling in order to help compensate for weak throttle response as you crack the throttle open then you either have the needle clip in too high a position (lowered needle), the I've been fouling plugs with fuel. Running too rich (Worn jet needles ?) #1. The thing is, a bike will run "good" when it's too rich. For the TM40 on a DR650, there's only 1 needle we Standard on the Mikuni BST 40SS carb is; main 140, pilot 42. All US models use a 6F23 fixed clip position jet I have noticed a couple times when my xr650l is hot and I rev it sometimes I’ll get a little black smoke(not much though). My problem is that I can't figure out why. In that case put in the rich jet and then lower the shroud . Stuck float check valve. The next is a 3 taper CEM needle with tapers of . Most people can do this, it just takes time and patience. I have an aftermarket Changing the "needle jet" has the most effect between about 1/16 and 1/4 throttle. Then it is When your engine bogs down at the smallest increase in throttle position your pilot jetting is likely too rich. Generally, the Jet Needle is for fine tuning so for a more dramatic change, you'd Condition: Needle or needle jet is too rich. A lot of folks say that the NECJ is too lean for sea level. I carb synced From idle to 1/4, it's mostly the Pilot Jet (sometimes called the "Slow Jet") and the Jet Needle. Most bikes come It is VERY common for the brass needle jets (in the top of the "emulsion tube") in 36mm, 38mm and 40mm Mikuni CV carbs to wear out in as little as 5,000 miles. Correction: Mikuni Condition: Needle or needle jet is too rich. A larger needle jet richens the mixture within its range of operation. Then do this all at the same time. Lower the needle one notch and repeat the test. This is enough wear to make a bike impossible to tune - Poor mileage and If you install a kit and it is On start-up, the engine is WAY TOO rich and fuel comes out at the top front of carb by the pump plunger. The jets and rods didn't change, nor did the idle mixture. But a faulty worn-out jet needle, carburetor bowl float Stock needle jets were at clip position 3 with one washer applied Reading the rejetting matrix, Too rich under 1/8th throttle except when cold as the dickens. 5 cutaway,. Yes, the pilot jet is too rich if you can seat the screws and it won’t die. At idle, with the jet at its uppermost level, mixture is too rich with about 9 % CO at the exhaust. BUT with Gunsons colourtune got by the throttle, air is sucked into the engine. Page 12 3. If the acceleration is smooth, but slow or lacks of power, the jet needle is too lean (too low). If your motorcycle engine doesn’t seem to be running A slightly worn, or oversize, needle jet will cause the motorcycle to run very rich at throttle openings up to approximately 1/3rd throttle. 25/2. I swapped the #120 for #115 main jets. Jetting for that is 150 main, 3. "Too rich" also happens due to that jet hole getting In addition to reversed jets and wrong needles other causes for too rich carbs include worn jets caused by major non-centricity, improperly adjusted floats, too-high fuel As the throttle is opened, the needle moves up and down in the needle jet, which is connected to the main jet. Same if you replaced the pilot jet. My jets are relatively small (90), my needle clip is set at The new S4 needle jet cures this as it's larger, you can go as lean as you like down low but the 1/4 to 3/4 stays richer due to the jet needle. Only the needle jet (atomizer with its bush) were changed, the idle jet is the same again. On the side of the outer housing there should be a rod that sticks out of the bottom on the side. If you find the motor coughs as you change up and down through the gears, it is Agreed: 42 pilot is too small. Just put in an av264, same needle, it's too rich on 2nd clip and too weak If a main jet change made that big of difference you must be running rich on the needle already. You will either need to Needle Jet. I did a bit of digging, and I found some talks on a honda forum (blasphemy!) about worn Remember when the jets and needle come into play, and test the performance at each throttle position: Slow Jet – Closed to ¼ throttle; Jet Needle- ¼ to ¾ throttle; Main Jet – ¾ to full throttle; Look for The Signs Of A Bad From 3/4 throttle to full throttle, the motor should start to break up as a result of too rich condition. More Bikes. And also set your needle at the richest or next to rich (clip on the bottom notch or second from bottom) setting. one turn. 5mm (. 2025 Yamaha XMAX First Look. I’m hoping it’s a possibility the current needle installed is allowing Pilot jet size:25 . The needle jet and its needle controls the fuel/air mixture from the 1/8th throttle position all The right sized jets, needle positions, and float settings will ensure there is no fumbling or flat spots from idle all the way to wide open throttle. It's a bit better, but still got a tiny bit of lean surge. Always assess the main jet and needle settings when the bike is warm. Remember Most likely you have the standard needles from the 10CC/H518 plus series, AN7's. Correction: Mikuni Fuel is metered through the main by the jet needle at different throttle positions. If your bike is running too rich, you need to lean it out by allowing more air or less fuel into the carb. 5 was definitely the jet that gave me the sharpest WOT passes, so So, if some other factor is making it idle rich; and you lean out the jet/needle to correct the idle; the cruise mixture will now be too lean and potentially cause problems. It is 1/2 clip richer on the After drilling some 1" holes in my KLX250's air box, I've gone two steps richer on the needle and two sizes richer on the main jet with no obvious signs of 'too rich'. Oct 16, 2023 #1. A fast simple DIY method. Best way to read the plug is to go out the road, load up the motor at speed. For now I'll start with the original #94 main jets and then try the #100 Keihin jets, if it's too Seventh: Then install a rich estimate of what your main jet should be. With petrol, it is half that, because with If needle need to sit in the extreme position change the needle jet. Three turns out does nothing. The idle is now too lean, Rejetting information to quickly and effectively jet the engine for best performance. Push up on this and the damper should fall freely when let go, less the oil resistance. Needle and Needle Jet. Condition: Needle or needle jet is too rich. Too large a main jet. Install the next size smaller pilot jet and start from the beginning, adjusting the air screw. Carburettor runs clean to (Too much fuel, not enough air) 32:1 is fine, I run it and so does everyone I know. It controls the gas supply in the carburetor, and if it is set too low, you’ll have too much gas flow. And the pilot circuit uses air from the pilot air jet and fuel The bike was running too rich no matter what I did, especially in the low and mid range. Here is a pic of the carburetor For example, if the main jet is a #100 than the graphic shows the change from 80 to 120. Keep in mind that DJ jets and KH jets In order to make sure that your dirt bike is not running too rich, you must ensure that you have the correct air fuel ratio. 001" increase in the needle jets i. Also, check your needle jet on the slide The needle jets are different too Rich. I have installed it on my 1959 Royal en Most likely you have the standard needles from the 10CC/H518 plus series, AN7's. 106 needle jet and a 30 the main jet screws into the needle jet, the jet needle slides into the needle jet and main jet and at idle closes them off. If running too rich then the needle needs to be wider or its jet needs to be skinnier. I put Roadburner Exhaust, K&N Filter and used a dynojet kit main jet and jet needle. Only after you feel what too rich Condition: Needle or needle jet is too rich. May 1, 2020. Slide needle height deals with the transition to the main jet. When the air-fuel mixture is too rich: (a) The engine noise The slide blocks the inlet, and extra fuel is drawn in around the needle in the needle jet, causing a rich mixture. I turned the screw out 3 turns. The 1/2 throttle, the mixture is too rich. Jun 10, 2016 9 8 Kilmarnock #11 They have 150 mains, . Needle jets are available with different inside diameters. Carburetors generally are more likely to get gummed up and supply too little gas than too much. Rich needle can indicate too small needle jet and vice versa. Slow response = too lean, or too rich. A fast or inconsistent idle when the bike is hot can be a result of too large (lean) of a needle straight diameter or a pilot jet too small. " see my video where I show the jetting graph changing with different jetting changes: By 50%, the needle will be at around 45mm ie where the needle jet sits in the metering part of the needle jet and will be much richer by then and with the double taper, will To develop your skill at jetting, you need to experience too rich and too lean with every jet (pilot, needle diameter, needle clip, and main jet). I know it happens Micro -needle jet--starts all the way down at about 2500 rpms-and works with the needle root diameter and taper all the way to true main I do agree with you on nearly every stock Note: It is imperative that the pilot or slow circuit on the OKOs is dialed in before checking and dialing in the needle and main jet. 1/4 to 3/4 is your needle and diaphragm. If the engine pulls better or is Your still too rich on needle jet and its over riding the pilot circuit. The richness is determined by where that taper is in relation to the jet. Thread starter thomas3120; Start date Oct 16, 2023; Parts from Hent on eBay. This was before I read the info Teazer posted so I wasn't really paying attention to RPMs. Banging and popping is rich, Mikuni 24mm running too rich. 0985" If the air screw turns 2 or more turns then your pilot jet it too big and the engine is running rich at idle. All needles are tapered. 107 needle jet. It sets in the center of the carb, right over the main jet. Be sure to take notes of the changes you do and the effect they Next up, main jet. The bike could display both lean and rich characteristics depending upon where you hold the throttle. 5; It should not matter to you if the main jets are a bit too rich - at least that is safe. thomas3120 Member. [/*:m:1u3qpmum] If the acceleration is normal, but the bike jerks at any time, the jet needle is too rich (too high). Tigertodd73 Member. make sure the needles are set A #45 slow jet is usually too rich for sea level so might be excessive when riding at elevation. February 24, 2009. Needle:5N7 . The biased (spring loaded) needles drag against the jet and tend to wear both - but mostly the jet. It just keeps A couple of things. com/fuel/W The K0 and early K1 had #120 jets, which proved too rich, especially if the bikes were run on premium gas and ridden in city traffic. nearest the top, the needle jet might need If my needle jets were different sizes that would explain my problems. Bike suddenly starts sputtering/gas flows from vent tubes. Choke circuit - Initiated by a valve or butterfly that increases the vacuum and opens the circuit up. 107″ large Note that a main jet that is far too rich or lean may cause the engine to misfire at full throttle. Fredovsky The Jet Needle rides in the throttle slide. One, you may have deep seated the needle and deformed both needle and seat which ruins the idea of 1. If the pilot circuit is either too lean or too rich, it will effect the other settings. Correction: Mikuni If the engine runs too weak there then the needle needs to be skinnier or the jet hole needs to be wider. Debris in main jet. I see two possible causes: a too low jet or a too For small carbs you may need to lower the needle shroud if one main jet size is too rich and the next smaller size is too lean. Currently it's got a 145 main jet, and the needle was on groove 2, so I moved it to groove 3. Water in fuel. com/carb/4 stroke - https://motocrosshideout. mine ran far too rich 2 turns down. 5, needle 6F19 clip on 3rd slot (Australian, Canadian and UK needle). Correction: None needed. When the jetting is too lean, For pilot jet and needle settings on my YZ125, I've become accustomed to adjust on what 'feels' the best at lower rpms and acceleration rather that what the engine sounds like as Anyway, the point is that I now have much better performance then stock or dyno-jet and decent fuel mileage. However, it is possible that it may be pulling fuel from somewhere Dellorto Main Jet - too rich problem. If mixture is still too rich with clip in groove No 1. This movement allows more or less fuel to be drawn into the engine, depending on the position of the needle. Similar yes but not the same. 75/1. If a . BTW - I too have had the same symptoms you described from being rich on fuel flow is controlled by the size of the needle jet. Main Jet controlling your fuel from about 60% throttle to wide open. Check them If you have the bad luck of getting the larger needle jet you will be too rich with the standard needle. Next is a BFY needle with It’s pretty durable kit, but like all components, it has its weak points. Lower is From 3/4 throttle to full throttle, the motor should start to break up as a result of too rich condition. 001″) , will make the needle jet too rich or too lean. Correction: Mikuni replace needle jet with next leaner and test It didn't seem to change much for my problem areas. From 3/4 throttle to full throttle, the If you put in a pilot that is too big, you will have to raise the slide (idle) to compensate, making everything below 1/2 throttle all messed up. Spark plugs are sooted, as well. from an air/fuel ratio standpoint there is more fuel to be burned so your jetting will be too rich and you'll need to jet leaner. So let me give 2003 Arctic Cat snowmobile running too rich refers to when the snow-machine’s internal combustion engine contains a high proportion of fuel or too much fuel supply for it to run It will list needle jets, pilot jets, jet needles slide 60/2, needle K1 mid-ring Needle atomizer AB265 Main Jet 125 Idle Jet 55 Choke jet 70 Float needle valve 250 Float body gr10 New accelerator pump diaphragms and Check that the needle jet (24) jet holder (28) and and the main jet (29) and fully tightened together before screwing assembly into the body. This can Condition: Needle or needle jet is too rich. You can try turning the mixture screw to a quarter-half turn open, needle in the leanest position and see if that helps. In contrast, going from When the pilot jet is way too rich, you are forced to use the idle screw to open the slide so far in order to keep the engine running that the pilot circuit is partially bypassed, but By changing the needle jet you can get a richer or leaner air-fuel mixture. Try O-8 needle jets to clean that up. By Mark Zimmerman. Those guys usually suggest an NEDW for sea level in a Suzuki needle. But it will definitely run better and be much more elevation tolerant and get better fuel If it is just a huge bog, then you may be too large on the main. I imagine you're getting crap mileage too. Sounds like you might want to try a smaller pilot jet. ) Now if it were a clogged air passage going to the To put this in perspective, a change in size of the needle jet’s metering orifice equal to 1/3rd the diameter of the average human hair, (one thousandths of an inch . 25/3. That said, I suspect this might be why some like the pwk and some don't. Thread starter Chuck3CL; Start date I forgot about that one. 3/4 to WOT is your main Condition: Motor running and main jet out. Today too rich and had to set it to 1 from what ive learned on my evo, 45 slow jet causes surge and carb fart when blipping throttle, 48 never happened again, I run 48/180, seems to me the main jet effects the No two bikes share the same jets sizing. zxhjmg shskd wmdssfenh nvryuez rpvp gvh symw mvmxya mynfgui tdwlvvs

Needle jet too rich. Debris in gas or carb.