Carburetor tuning on harley davidson aftermarket motorcycle. Now, holley efi products power these cars and are dominating the performance world. If you want to link to this page on your site, please ask we are perfectly willing to allow links as long as proper. At least my kids say it smokes too much and doesnt have a lot of power. Holley is pleased to announce the expansion of their popular training courses, thats right, consumers will now have the ability to learn carburetors from one of the most trusted names in performance. Holley 1940 1945 1946 6145 6146 parts page 1940 diagram. If you look at a carburetor, you will notice a rather large hole going from one side to the other. These instructions must be read and fully understood before beginning installation. How to tune and adjust your carburetor yourmechanic advice. Tuning and assortment kits holley performance products. This seems to be a hard book to find so if your thinking about purchasing and one is a available, you should buy it while you can.
If this manual is not fully understood, tuning should not be attempted. Make sure the engine is at normal operating temperature, not too hot or too cold. The stock cv carburetor has a venturi diameter of 40mm 1. Tuning a carburetor equipped supercharged engine whenever people see a carburetor equipped supercharged engine in a hot vehicle, they cant help noticing how impressive it looks, and they wonder how much power it produces. Air passes into the engine through this hole venturi. Set mixture screws at recommended settings, as a starting point. By the end of 2006 we were able to produce a better performing wb3a carburetor with revised drillings and oringed thro. The sniper has some advanced tuning features that should allow you to get the idle under control. That is the job of the fuel bowl vent and one of the carburetors key elements.
The tuning goal is to optimize the quality of the airfuel mixture coming from the booster throughout the power band. Holley carburetor tuning into the basics about holley carburetor tuning. To get best lowend power, set float height fuel level so that the engine will accept full throttle, without missing or stumbling, in 2nd gear from 2. Serious injury, death and property damage can result from the improper use, control alteration or maintenance of motorcycles. Holley carb adjustment basics just a quick overview of how to adjust a holley and what to know. Failure to follow these instructions, including the pictures may result in subsequent system failure. This carburetor is not intended for rv and performance type camshafts and header application. All other components are cleaned, tested or rebuilt to meet o. With the engine turned off, have an assistant slowly press the accelerator pedal to the floor, while you watch the throttle for any sticking or binding. Carburetor identification, holley part numbers, basic troubleshooting, onvehicle tuning and adjustments, stepbystep repair and overhaul, performance and economy modifications, professional tips and tricks. Road tuning start by taking your carb apart and writing down the sizes of the jets, the actuation point of the power valve, and the size of the accelerator pump squirter. Nov 14, 2006 holley twobarrel carburetor tunable metering block. Variable venturi or slide carburetors the goal of providing the stochiometric ratio, 14.
To print a copy of this article or save a copy for reference please click on this link. Jun 04, 2014 how to tune the carburetor on a chainsaw, and any other two cycle power equipment. Search using model number, interchange number, part name or number, vehicle yearmakemodel, etc. Hello group, the keihin constant velocity carburetor on your honda ch250 should perform well with the standard recommended settings under average load, climatic, and barometric conditions. Holley has been the undisputed leader in fuel systems for over 100 years. Holley twobarrel carburetor tunable metering block holleys tunable metering block makes custom fuel curve tuning possible for us all.
Holley twobarrel carburetor tunable metering block hot rod. Instruction manual to download this manual or others, go. Set for smoothest idle and 2nd gear, 4k rpm, steady state cruise operation. Holley carburetors powered every monster energy nascar cup team and nearly every nhra prostock champion for four decades. All you will need to adjust is the idle mixture and possibly the jets. All constant velocity cv carburetors are designed to compensate for changes in altitude and barometric pressure. As the engine compression goes down, over time and miles, the suction or vacuum in the carburetor venturi is less then it was when the engine was new. The model 5200 and 5210 holley carburetors are staged two venturi carburetors. As the velocity of the air entering the carb and then the engine increases, its pressure decreases, creating a low pressure or vacuum in the venturi. For smoothest idle, 2nd gear 4000 rpm steady state cruise, and 18 throttle high rpm operation. If you are replacing an existing holley carburetor, you may need to purchase and install a throttle lever extension holley pn. The best way to tune a carburetor is to start with the right one.
Mixture tuning on your harley davidson cv carburetor is a simple procedure that can easily be performed with basic tools. Carburetor tuning must be done to provide max power without overheating the 2 stroke engine. The old sportster needle trick worked fine years ago when there were really no other alternatives. Option 1 is to purchase and install one of the holley efi dualsync distributors on your engine. Turn the carburetor over so the bottom is facing upward. Online provision for airfuel tuning during testing the carburetor is simple in design and does not have moving components. An adapter harness is available to connect this distributor directly to the sniper efi throttle body. Type what youre looking for and we will do our best to find it. Congratulations on your holley carburetor purchase. Attaching custom or specialized throttle linkage to a holley carb.
Fuel enters the carburetor at the fuel inlet and flows through the float needle valve into the chamber. Since a motor is switched to the motor is running in a. I removed the plugs and cleaned off all the soot and set. Walbro carburetor tuning and modifications in 2006 we spent many hours out testing with our junior drivers in the national classes. Please read and understand this manual completely to assure.
Tuning your harley davidson carburetor is simpler than most feel and can be carried out with a handful of common tools. It has a separate port for air and fuel, where the individual ports could be modified or tuned to achieve the required airtofuel ratio. The carburetor should open smoothly to wide open throttle. Instruction manual to download this manual or others, go to. Mar 07, 2014 tuning your harley davidson carburetor is simpler than most feel and can be carried out with a handful of common tools. Two barrel carburetors should be tuned in the same manner as the primary side of a four barrel carburetor.
I am a carb tuning novice and everything in the book was well written and easily understood. The float chamber is internally vented into the air horn 2. If your engine is running too rough, its important to adjust the mixture and find the correct idling speed to decrease engine. This is the side that receives the outside air through the air filter. Because there is less suction there tends to be less fuel mixture. Quadrajet performance carburetors with electric choke. Carburetors in general are mysterious things to many, and when you start putting a bunch of them on a multicylinder. This is for application with performance modifications such as intake manifold. Drawback of simple carburetor a simple carburetor as described suffers from the fact that it provides the required airfuel ratio only at one throttle position. By the end of 2006 we were able to produce a better performing wb3a carburetor with revised drillings and oringed. Push the throttle lever rearward to its wideopen throttle position and adjust the transmission. A 3dimensional vector plot on a pl ane for a mass flow rate of 0. Preparation setting up and tuning an su carburetor is based on the premise that both the engine and the carburetor are in good shape. Whether it is street strip performance, or just getting the most out of your hot rod, the street demon will give you optimum performance.
Analysis and optimal design of a producer gas carburetor 15 figure 15. Today, several distinct types of carburetors exist. All bolts and linkage parts are zinc plated, and the casings are tumbled to a chrome. Holley 1904 1908 1920 1960 parts page 1904 1908 1960 diagram 1920 diagram. Please do not plagiarize this page it took years to develop and write and is not based on any other previous work by anybody else. Holley and other manufacturers offer a wide array of single and multiplecarb manifolds. If you find that no setting of the mixture control seems to have any affect on the richness of the mixture then perhaps you have screwed the mixture control in and hit a false bottoming of the mixture control rod. If you need to adjust much else you probably dont have the right carb for your application. Pdf analysis and optimal design of a producer carburetor. Basic idle in the installation manual but i think you will find that it is already far below the idle level at. These tuning features are all accessed using the handheld controller. Since then, carburetor technology has evolved and variations on the original design have been used to produce engines with increased power and efficiency. After confirming the carburetor mounting surface is clean.
The dealer and dealers customers must exercise good judgment in the use, control, alteration, part selection and installation, and maintenance of motorcycles. If you use the oem needle, the main jet will be replaced with a jet 10 larger than the oem. How to tune the carburetor on a chainsaw, and any other two cycle power equipment. Install the new throttle ball, lockwasher, and retaining nut to the carburetor throttle lever in the same position as the existing carburetor. Before you begin to tune your carburetor for your particular vehicle, you must get a feel for your vehicles performance, so that. This is a con tinuing operation as long as the engine demands fuel and the fuel pump supplies fuel to the carburetor. All instructions and the ezjust are intended for a harley cv carburetor only.
Do not underestimate the ability of the stock keihin cv carburetor to produce good horsepower. When the fuel reaches the proper level, the rising float closes the needle valve. The needle valve is springloaded to provide uniform seating under all operating conditions. Holley carburetor preparation and tuning guide muscle car diy.
The next item is the venturi, which is a portion of the carburetors main air passage that momentarily narrows down. As a single solution, or partnered with products from other holley companies we can give you the edge you need over the competition. It is sometimes colloquially shortened to carb in the uk and north america or carby in australia. Cv performance harley cv carburetor mixture tuning. However, this item may be purchased online to be shipped to home or may be purchased in person by visiting a napa store.
Carburetors were invented in the latenineteenth century. Figure 1 carburetor torque sequence all holley carburetors note. In this case the throttle plate is parallel to the length of the tube, allowing maximum air to flow through the carb. The following should be checked on the engine prior to setting up the carburetor to determine if the situation will lend itself to optimal timing, or. There is a basic idle speed setting search for tuning. For more than 115 years, holley has been producing quality fuel system components and now is your chance to learn in a handson classroom.
At all other throttle positions, the mixture is either leaner or richer depending on whether the throttle is opened less or more. Carburetor question holley nh by dave hjortnaes, menomomonee falls,wi on sunday, october 11, 2009 07. Go back to carb help index go back to main page carburetion basics by don kuhlman one of the more commonly misunderstood systems on most motorcycles is its carburetor s. Now, i wont use any other needle in my cvs except this one from cvp. Every carburetor is assembled by hand using a master rebuilding kit. However, in many cases service adjustments of individual systems may be. Increase or decrease the amount of the mixture according to engine speed and load changing. But they also see an engine they think is almost impossible to tune, is not very reliable, and will overheat at the drop of a. Finding the correct air and fuel mixture will help extend the life of your engine. Put it all back together, check for leaks, then drive it until the engine is warm. Adjusting the carburetor is a lot like tuning a guitar or other stringed instrument.
Level 2 lv2 the production process is the same as as level one however, level 2 is for streetstrip vehicles, tow vehicles, rvs and watercraft with modified engines. The vent valve seats a pas sage which lebds from a point in the carburetor bore just above the throttle valve to an external bleed hole at. To carburate or carburet and thus carburation or carburetion, respectively means to mix the air and fuel or to equip. Carburetor tuning carburetor tuning means adjusting the screws that let in different amounts of air and fuel. Components of carburetors usually include a storage chamber for liquid fuel, a choke, an idling or slowrunning jet, a main jet, a venturishaped airflow restriction, and an accelerator pump. We apologize that this item is not available for pickup in store at this time. Base plates are rebushed to remove excess wear from around the throttle shaft to stop certain vacuum leaks. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Holley 1904 1908 1909 1920 1960 1940 1945 aa aa1 2100 2209 2210 2300 5200 4000 4150 4160 4180 4165 4175. If it needs to be changed the range is normally 50 to 60. Float heights, unless otherwise specified in the installation guide, are measured from the gasket surface of the carb body to the highest part of the top of the float.
This easy method is a excellent harley tech tip that applies to all harley designs from 1989 to 2006 that use the cv frequent velocity fashion carburetor. Carburetor tuning must be done to provide max power without overheating the 2. Correct any sticking or binding conditions before proceeding. Carburetor technical support holley performance products. Holley doesnt machine this surface on all carburetors, so when you disassemble your carb, look for a lip at the top of the primary or secondary metering block mounting surface. The air bleed uses main jets, the stock size is 40. Carburetor installation and tuning ultima products. Carburetor, device for supplying a sparkignition engine with a mixture of fuel and air. A carburetor american english or carburettor british english is a device that mixes air and fuel for internal combustion engines in the proper airfuel ratio for combustion. If this manual is not fully understood, installation should not be attempted. National carburetors dat814 remanufactured carburetor. Anytime you rejet or change exhaust or air cleaner intake it is suggested to adjust the mixture. The goal is to help you understand the thoughts behind the demon, and to increase your knowledge of carburetion on a whole.
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