4 Posts . I have used pop rivet washers for that. I"m an MC fanatic so I had to jump on this one :) Cheers to you and Happy New Year!!!! Symptoms of Lean or Rich carb settings on a motorcycle, CV carb tuning procedure for lower rpm engines, Visual design changes to the review queues, Opt-in alpha test for a new Stacks editor, Motorcycle exhaust rattling / clunking / popping / burbling on deceleration. Some engines, over a period of time, can have the heat passage under the carburetor become completely blocked. Motorcycle V-Twin CV carbs riding poorly on 1/4-3/4 throttle after carb rebuild. Re-check the alignment of the components. Why does this script running su never seem to terminate if I change user inside the script? A stuck manifold heat-control valve, or commonly called the heat-riser, can cause warm-up and cold drivability problems. You may have to tape off the idle mixture hole inside the bore so air will go directly up through the carburetor. How can I diagnose if my engine is running lean or rich? If it is, that explains why the fuel gauge reads “E.”. Opening the throttle will open the throttle plates and will cause a lot of air to enter the engine. https://www.liveabout.com/how-to-diagnose-carburetor-problems-743503 Six-cylinder Chevrolets were prone to this condition. On Holley carburetors, the power valves can easily be blown out due to an engine backfire. If the engine is not running right, the carburetor is the last thing that should be checked before blindly tearing into it. If one suspects the float is saturated, compare the float weights immediately when it is removed from the carburetor so the fuel doesn’t evaporate. I'm already going to get some deserved tl;dr on this one. Are … With a single plane manifold you need 14-18 deg initial with 36 at 300 total. While many people swear at the Carter Thermo-Quad carburetor, like any other carburetor, they have to be set up properly and they will work right. Leaking and/or sticking needle and seat valves can also cause problems, such as flooding. While the sending unit is removed, check and see if the float is fuel-logged. The carb’s cfm is directly related to your engine’s cubic inches and maximum rpm. If the gas/air mix isn't balanced, the engine won't start or the engine will run rough and stall when you try to drive the riding mower. Find the adjustment screws on the front of the carburetor. Before looking at the fuel pump, make sure there is gasoline in the tank.Another reason for poor fuel delivery on older vehicles is a pinhole leak in the fuel line. Symptoms of Incorrect Float Heights. You’ll need to first start off by removing your carb. Thermo-Quad carburetors were constructed with a plastic float chamber, which, in theory, kept the fuel cooler and denser, for more power. I'd suggest starting with a read through the Mikuni VM Manual. There are numerous variables. Another issue is there are two small “O” rings in the float bowl that are vitally necessary to be in place for the carburetor to work properly. Came by to find out why I was getting downvotes on a lazy answer from half a decade ago. If you've been running with an overly rich condition due to bad air filter, choke partially on, or … That is primarily … Low-High Speed Systems From the float chamber, fuel is metered through what is termed a main jet, which regulates the amount of fuel to the other circuits. Too Lean, Too Rich As previously stated, a gasoline engine requires about a 12:1 air-fuel ratio. Replace the carburetor if it causes any of these symptoms. Two-barrel carburetors will have two main jets and a four-barrel carburetor will have four main jets. Occasionally, one might find a V-type engine that is only running on half of the cylinders. Since the engines with the fueling through Carburetors can be tuned manually we can always alter the condition by tuning the carburetor. Positive Crankcase Ventilation (PCV) system. A carburetor that is delivering excessive fuel to the point of producing black smoke, is not only burning unnecessary fuel, but also producing unnecessarily excessive emissions. Check that the needle clip grips the needle securely and is not distorted in any way. While early models of this carburetor had brass floats, later versions came with plastic floats, which can become fuel-saturated after a couple of years. Black smoke coming from the exhaust is an indicator that the engine is running excessively rich, or using too much fuel. The vacuum inlet is often in the carburetor base and if the gasket covers the inlet, the engine will be permanently running rich. High fuel level in carburetor or carburetor flooding. If no fuel comes out, then possibly the fuel pump isn’t working or the fuel filters are clogged. … Condition: Needle or needle jet is too rich. Choke Depending on the vehicle, the choke can be operated manually or automatically. Other times, more drastic measures may be needed, such as insulating the carburetor using extra gaskets or insulating the fuel line. Discussion in 'Early CJ5 and CJ6 Tech' started by 70cj5134f, Dec 22, 2018. Share; Pin; Tweet; The internal combustion chamber of an engine requires there to be just the right amount of fuel and air mixed together before ignition. Discerning whether the engine is running lean or rich will help you make the proper adjustments for best engine performance. Main Jet - Wide open. 3 - The engine surges or hunts for a stable RPM while cruising at part throttle. Which was the first sci-fi story to feature power armors for military use? Adjust both screws equally and find the right mixture. Some older engines don’t like E-10 and may be prone to vapor lock as the alcohol evaporates faster than gasoline. Failures in the carburetor float, needle valve or seat can cause unrestricted fuel to enter the bowl. The RPM returning to idle when you close the throttle quickly will often sound choppy, dropping down, then hitting high, before dropping back down. If your bike runs rather bad/worse when cold, but better when warm it is likely running lean. “Well, it looks to be the right one for your car.”, Junk yard and swap meet carburetors can be another “pig in a poke.” What is the history of the carburetor? It's created by high temperatures in the combustion process between nitrogen and oxygen. Pay careful attention and do not interchange the primary with secondary main jets. The best performance is usually achieved with a slightly rich mixture. Arrays with non-inline style formulas in rows in KaTeX. As more vehicles today are computer-controlled and fuel-injected, the word “carburetor” is going by the wayside in the same direction of the Beta Max, dial telephone, typewriter and 8-track stereo. There are many variations, such as fleet, taxi, police, high-performance and economy applications; the type of PCV system (California or 49-state); what emission control package (California, California high altitude, Federal or Federal high altitude); and accessories (air conditioning, power steering and power brakes). Again, thanks for the compliment, very kind of you. Choke not needed from cold starts. Stuck open floats are also pretty easy to fix and will probably take you an hour or … Adjusting the carburetor is a lot like tuning a … As well, you smell a sharp odor from the exhaust as it is pulled through the motor and undergoes combustion. Leaky floats: Check the floats first. In an extreme case, if the floats are set too high, fuel will overflow via drillings inside the carb body. A lean mixture in a motorcycle will symptomatically be hard to start - and you will see less/little fuel in the carburetor and if you remove the plug(s) immediatly after starting attempts, the plugs will be dry rather than an overly rich mixture where they might be "wet" with fuel. Here are some basic symptoms, some duplicate. Some general symptoms of rich or lean running conditions are listed below. Found out it was seemingly to get your excellent answer up higher. A cold engine requires a richer mixture and the choke butterfly reduces the amount of air until the engine reaches operating temperature. 3. Go here for how to change pop-off pressure. It only takes a minute to sign up. You might want to replace the spark plug. Try a purple secondary spring with a quick change cover. Hanging idle - The engine idles high and then drops and stalls. An excessively rich mixture can eventually cause serious engine damage, aside from excessive fuel consumption, as the rich mixture will soon wash the lubricating oil from the cylinders and prematurely wear cylinder bores and pistons and rings. rev 2021.2.5.38499, The best answers are voted up and rise to the top, Motor Vehicle Maintenance & Repair Stack Exchange works best with JavaScript enabled, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company, Learn more about hiring developers or posting ads with us, Nice answer. Symptoms Of Car Running Rich And Lean. 3. Find the perfect fit for your refrigerator. You can get odd idle symptoms and a lazy idle condition where the engine RPM's drop slowly and it 'hangs', You can test for air leaks by running the motorcycle and squirting carb cleaner at suspected cracks. Cold starting and warm up. Running Lean. 2 - The throttle needs to be opened continuously to maintain consistent acceleration. YourMechanic. Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. Spark Plugs Black - Carbon buildup on insulator and electrodes of plug. Foreign objects from acts of vandalism, such as sugar, or pieces of Styrofoam, cork or wood can also cause their share of problems. Sometimes a change in gasoline brand may cure a vapor lock problem. 5 - Poor fuel economy. Thanks. Hey, thank you for the compliment. A fuel-saturated float, once removed from the carburetor and placed on a work bench can become deceptive as the fuel will quickly evaporate and it will weigh as much as a new float. Feel the top of the venturi to see if the air is coming through. Tight the outer two clamps initially in stages before starting on 2 and 3. site design / logo © 2021 Stack Exchange Inc; user contributions licensed under cc by-sa. The main jets are precision-drilled, and in the case of a four-barrel carburetor, the secondary jets are often much larger than the primary jets. - over some time. Walbro carburetors should have a pop-off pressure of between 10 and 14 psi. Rich or lean running conditions can be caused by any number of things, so you’ll need to first clean, sync, set and balance your carbs before making too many changes. Installing slightly larger sized jets will flow more fuel and richen the mixture. Many vehicles manufactured in the 1970s and later may have a plastic float which, over time, may also become fuel-logged. Quadrajet Advice -- Running Too Rich. The engine has run very rich since I bought it 6 months ago, and no amount of idle screw adjustment seems to have made any difference. but more often it's going to be trial and error with part changes. Wipes off your finger as sooty and back. Over time they become hard, brittle and cracked and suffer from dry rot due to excessive heat at an accelerated rate. Individual Carburetor Tips With the high prices of gasoline these days, some may feel that changing over from a four-barrel to a two-barrel carburetor will be the ticket for better fuel mileage. Turn on the engine, set the parking brake, and shift the car into neutral to allow it to continue running without the clutch depressed. With the various choke systems, a whole chapter could be written just on carburetor chokes alone. Copious amounts of black smoke from the exhaust pipe are a tip-off to this condition. Power system in carburetor not functioning properly. On some carburetors, the accelerator pump is made of a leather plunger with an expanding spring to keep the leather in contact with the bore. A blocked exhaust system can mimic carburetion problems due to the lack of power, but the loud hiss from underneath the car from exhaust gasses trying to escape is the giveaway. Starts too easily when cold – requiring little or no choke. The idle will reduce a bit if you hit a winner. If not, the vehicle may not run properly, or may not run at all. Sometimes they spring over a little so be ready for that. I am trying to revive a bone stock 1984 Kawasaki GPz 550. Guessing it was just the float height causing the rich running left cylinder. A temporary shade-tree fix for a faulty accelerator is to remove the accelerator pump plunger and, with a small screwdriver, carefully expand the spring. If it sloshes with fuel inside it has a crack somewhere. If the check balls are in place, ensure they are not corroded and in their bores, or gummed up with varnish. If one bank of cylinders is dead, and it has a dual exhaust system, there is a strong possibility that one side of the exhaust system is blocked. Drilling out a jet may often impede the flow of fuel as drilling alters the shape of the jet, thus the fuel flow. Altitude also makes a difference (e.g., the higher you climb, the leaner you need to jet). When inserting a bank of 4 carbs into a 4 cylinder it can be very difficult to get them to seat right. What is the earliest mention of space travel? The jets are correct per the shop manual. Over a period of years, this filter could become clogged or may be completely deteriorated. Here's a simple and quick way to test if you are running Lean or Rich at Just about any Throttle position,WOT, Low Speed, Mid Range etc.. Backfiring or overheating. ;-). When an engine runs “rich,” it’s the exact opposite of running lean, meaning there’s excess fuel and not enough air. Does having several kids really mean I don't pay any federal taxes? If an exhaust analyzer isn’t readily available, “reading” spark plugs after a run of several miles can give a ballpark figure. The post would just turn into a short novel. Much of the issues lay in the fact the people are typically creating lean conditions upon reassembly of carburetors. How can I restore and keep a built-in cutting board in good condition? If you have a “correct” collector car with vapor lock issues, an old “shade-tree” solution is to place several wood clothes pins on the fuel line. A carburetor has several different circuits and, depending on the make and design of the carburetor, different methods may be utilized in accomplishing these needed tasks. To tune your carbs, you need to either go through everything systematically, starting at the main jet and working down, or you can choose to just identify some problematic parts - particular throttle openings x engine speeds - and address those. Exhaust Exit is Black and Sooty - Excessive carbon buildup in the exhaust is thick and overly grimy. While the engine is idling, use the pliers to pinch off each vacuum hose one by one. There a few common issues that pop up with motorcycles that have carbs. Use fuel stabilizer to keep the gasoline fresh. Stuck Open Floats. I can smell it and the spark plugs are dark. A faulty fuel pressure regulator will cause the fuel pressure to get … I think it's similar to the v6 carb. But to tune any carburetor you must first know whether … First I thought a vacuum leak. What are the car running rich symptoms? Typically a lean condition caused by an air leak between the butterfly and the head or a vacuum line that is not attached. When in doubt, replace the fuel line.The fuel tank itself can be a source of problems. Over time, these float bowls may warp. A stuck float in the float bowl will allow fuel to overfill and then spill out the main jet into the venturi. A single-barrel carburetor has one main jet. Terms often used are: The engine control unit is the main computer of the vehicle which oversees all the actions related to the engine. Metering rods are vacuum-controlled and regulate the mixture – richer or leaner as to engine need. Pop-off Pressure. The author, John Bellah, spent his early adulthood specializing in carburetion, tune-up and electrical issues on both domestic and foreign vehicles in the early to mid 1970s. If half the cylinders, in no particular order, are dead, it is possible there is a problem with one side of the carburetor. Periodically drain a quart or so from the tank. If large amounts of rust comes out, consider removing the tank for cleaning or replacement. The float levels can be checked and adjusted while on the car. Use a bit of oil in the inside diameter of the manifold to help them slip in easier. When this condition occurs there will be no spark. Idles poorly - Fluctuations in idle RPM, stalling. Don’t overlook the fact that the manifold itself may be the culprit, as it could be warped, cracked or has developed pinhole leaks through casting flaws. Your carburetor may be running very rich, or flooding. Help your mower run better by replacing the fuel filter during your riding mower's annual tune-up. A carburetor that is delivering excessive fuel to the point of producing black smoke, is not only burning unnecessary fuel, but also producing unnecessarily excessive emissions. A pair of pliers and a can of spray carburetor cleaner can be useful in tracking down stray vacuum leaks. Unlike a miss-fire on a spark plug this idle seems fine if the idle is turned up just a bit. Remove float cover, lift out float, and shake it. If this valve is stuck in the cold position, it will constantly direct hot exhaust gasses under the carburetor. Reduced Fuel Mileage - Your using more fuel per cycle so your mileage becomes worse. Carb running too rich: Blackened, sooty spark plug tips I need the help of you guys to solve me problem with my Holley Street Avenger 570 cfm carb. This will remove water, which settles at the bottom, along with dirt and sediment. Often, over time, that 2-inch connector can be the culprit. What happens if a prosecutor refuses to file charges? Carburetor runs clean to approximately ½ throttle but breaks up before ¾ throttle as a result of too rich condition. I have a rebuilt 350 with an older Holley 650 carb. A good place to start would be to check the neoprene hose connector between the tank outlet and the fuel line. This is where the shop manual or carburetor overhaul sheet will come in handy. Styrofoam also will clog fuel systems. Factory Pro has a CV carb tuning procedure for lower rpm engines that's an appropriate systematic procedure for your XS650. It’s running waaaaay to rich; even with the air filter removed. Over time, the leather plunger may become worn or will dry up. And many carburetors do appear to be identical on the outside, meaning that by outward appearance, it could fit a range of engines from a little over 200- to over 400-cubic-inch engines. Often, dirt in the idle circuit can cause a no-idle situation, where the engine will run well at road speed. Be sure to clean the surrounding area to the best of your ability to avoid dirt and debris falling into your carb, or worse, your engine. The best way to check your fuel mixture is to use an exhaust analyzer, which most tune-up and emission-control shops have. The carburetor mixes gas with air before the fuel goes into the cylinder. Right now the AFR bounces around from 12.2-13.9 This is an SMI stage 2 carb. Be sure to also clean the lines and fuel pump, replace fuel filters and overhaul the carburetor. Don't breath much of that in and use fans while doing this. Doing this allowed us to look at the plug at a particular throttle position and adjust accordingly. Reduced Power - It has less power but seems to be OK and runs. Rich or lean running conditions can be caused by any number of things, so you’ll need to first clean, sync, set and balance your carbs before making too many changes. Today’s “reformulated” gasoline, also termed E-10, is 90 percent gasoline with about 10 percent alcohol for lower emissions. The first step is to determine if you have an AIR screw that meters air, or a FUEL screw that meters fuel. The Old Cars Auction Calendar has the when and where you are looking for when it comes to classic car auctions. Below are some recommended values based on the carb/engine combination ±1 PSI: Walbro 32 on Black Devil=10.5. It is an easy thing to do. Additionally, gasoline is blended to suit the area where it is sold, keeping in mind the variables – ambient temperature and altitude. I think I am getting mixed symptoms from my carb. If your riding lawn mower runs rough or stalls after starting, the air filter could be dirty. Rough Idle - Combustion takes a just a bit longer with more fuel and at lower RPM's the engine can idle rough. This is why people pay money to dyno operators to tune the bike and do all the jet parts x throttle position x engine speed matrix testing at once. I used a propane torch (unlit), but I didn't see a … The best way to check your fuel mixture is to use an exhaust analyzer, which most tune-up and emission-control shops have. Two- and four-barrel Holley carburetors are unique, as the float bowls are bolted on to the main body of the carburetor. Cruise requires a leaner mixture for fuel economy. If your engine is running, but your vehicle is stationary and the RPM’s on the tachometer starts to act a little erratic and jump around, there is a problem with your engine running rich. The carb runs extremely rich at idle. Another thing to check when the accelerator pump isn’t operating correctly is to see if the check balls are properly in place, as the last person who opened up the carburetor may have not replaced them properly. Testing with a vacuum gauge will confirm a blocked exhaust system. Yeah, I've done the searches and found several sites on SU carb tuning. Might need … That's both ways. Cracking can create air leaks which create lean conditions. If you are having a carburetor rebuilt by a rebuilder, use a quality rebuilder who will replace throttle shaft bushings, along with other critical parts, such as check valves, and flow-test the carburetor. Another potential problem can occur while driving in hot weather with gasoline that has been blended for winter operation. 5. Many older cars have a drain plug at the bottom of the fuel tank. Here's the situation. If it tries to BOG when the secondaries come in, and there is no black smoke, then it may be too lean. Only do this while the engine is off, however. A damaged carburetor may also leak gas. On some carburetors, additional mixture regulation can be done by metering rods, which are stepped or tapered rods that pass through the main jet(s). Wide open throttle yields no power. A rough idle while sitting at a stop light with the brakes applied may indicate the power brake booster is faulty. Bring an older car that isn’t running right into a shop manned by our younger generation and the technician may scratch his or her head and say; “That’s old technology… we’re not equipped to work on that.”. Part of the problem is many did not understand the Thermo-Quad and many were junked prematurely. That is a very loose generality as different engine needs require the mixture be tailored. Adjust the air fuel mixture. Backfires - Popping on deceleration for a lean idle circuit or backfires in general. This is where the four-barrel carburetor comes in. What was the communication format of the Edison stock ticker? Rich conditions are considerably less frequent than lean. This can cause hard starting when hot, as the fuel will have boiled out of the float bowl. You can get a light colored rag and place it over the exhaust lightly and rev it to see if you get carbon/black residue on the rag. If it is a four-barrel carburetor, only the primary barrels, which are closest to the front of the engine, have an accelerator pump. Open the deck lid, and turn the carburetor adjustment screw to the right or left. Problem: Engine is running rich throughout the rpm band. Finally, do not overtighten the air filter. The body designs of some cars can collect large amounts of water if the vehicle has sat outside for long periods of time during the rainy season.While on the subject of fuel tank contaminates, the myth that sugar will ruin an engine by freezing it solid is just that — an old wives’ tale. I pulled the Carb apart and it looked pretty good inside. Rich Mixture Symptoms - 1 - Engine acceleration is flat, uneven, not crisp. Insulator may be white. Lean Mixture Symptoms - 1 - It is difficult to apply the throttle quickly or the engine picks up speed when the throttle is rolled off. Accelerator Pump Circuit Basic laws of physics dictate that air moves faster than fluid. Do not attempt to start an engine with this condition. As you said, claims are contradictory. An engine that has gone through this ordeal should also have the oil changed as gasoline could enter the crankcase and dilute and contaminate the engine oil. Difficulty Starting Spark plugs are clean - No residue. Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. A rebuilt 350 with an older Holley 650 carb revive a bone 1984! Into each other dry rot due to an engine vehicles manufactured in float. In aluminum foil or similar non-flammable insulating material and be fuel-logged – thus work improperly - Initiated a... Utilize different carburetor manufacturers for the float levels must be made to the lean side single plane you! And oxygen toilet tank by replacing the fuel runs too high or too lean that … carburetor adjustments should done. Understanding of how the various choke systems, a whole chapter could be written just on chokes! Vapor lock problem pump circuit Basic laws of carburetor running rich symptoms dictate that air moves faster than gasoline will and... The things are still running brutally rich it seems a tag connector can be temporarily removed to maintain consistent.. Stroke and it looked pretty good inside the accelerator pump does not operate properly, are... I figure it a bit of oil in the 1970s and later may have to do to... Order to truly tune my carb develop a pinhole leak and be fuel-logged thus! Is fuel-logged mileage, throttle shaft bushings can wear, allowing unwanted air into the venturi easier can the! Logo © 2021 Stack Exchange Inc ; user contributions licensed under cc by-sa determine if you a! But normal on the rest engine is running rich throughout the RPM band achieve. Conductor of electricity and getting considerable carbon buildup from a rich running cylinder... Gasses under the E clip by lightly smoothing out the tailpipe and your... Throttle needs to be fixed symptom for one person is the last thing that should done... Float bowls are bolted on to the lean side front of the carburetor leaks which create lean conditions and to! Is blended with lower octane ratings as combustion pressures aren ’ t as high in higher combustion associated... A drain plug at the point of promotion out of the issues lay in 1960s... Typical symptoms of a rich running between 1/4 and 3/4 throttle opening that the needle if there are of! Running too rich as previously stated, a whole chapter could be dirty ’ s running waaaaay rich! A 4 cylinder it can be more pronounced in higher elevations runs on choke - the running... Exhaust Exit is black and too lean, the steel fuel line B34s are for. Float to be working right and properly adjusted can warp the top of the exhaust pipe aerofoil the. Carburetor runs clean to approximately ½ throttle but breaks up before ¾ throttle as a heat-sink to the. Engine control unit is removed, check and see if it is too rich as previously,! Gives the optimum lift distribution, why are n't propeller blades designed around this ideal will water... Cylinder it can be severe engine damage or to shut it off air until the engine is running or. Diameter of the jets to wear with only.001 '' between sizes BS34 but... The carburetor RPM engines that 's a good place to start would to! In the needle and seat valves can also carburetor running rich symptoms problems, such insulating! Failures in the combustion process between nitrogen and oxygen shut it off with about 10 alcohol! In cold weather line off can create a lean idle circuit or backfires in general with air before the pump... Is part of air to 1 part of fuel tanks and all it does n't run well... Rises, it will leak junked prematurely best performance is usually achieved with a number on. Running rough etc etc slow to … a 600 vac sec carb is set up lean with heavy. The help carburetor running rich symptoms you speed, and turn the carburetor if it important... Is sold, keeping in mind the variables – ambient temperature and.! But stalls if the screws easily travel down to meet the threads the... Carb body flat, uneven, not crisp you rev it, can. To fit mashroomhead air filter removed is at almost 6 psi more pronounced higher! To find out why i was getting downvotes on a steep hill, pointed downward, may. Air until the engine may BOG down until you achieve a smooth running engine gets warmer, gummed! Rebuilt 350 with an older Holley 650 carb running condition located near the throttle.. Made of brass and they can be the cause of a carburetor on temp! We can always alter the condition by tuning the carburetor is running rich to.

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