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| ====== IH: Carburetor, Intake Manifold & Exhaust - Sub-01C ====== | ====== IH: Carburetor, Intake Manifold & Exhaust - Sub-01C ====== | ||
| \\ | \\ | ||
| - | ====== Bendix Zenith I6P12 Carb (1972-Early 1976) ====== | + | ====== Linkert Carb Functions, Adjustments, Tuning ====== |
| - | \\ | + | |
| See also in the Sportsterpedia: \\ | See also in the Sportsterpedia: \\ | ||
| - | * [[techtalk:ih:carb01#bendix_zenith_i6p12_carb_1972-early_1976|Bendix basic carb information]] | + | * [[techtalk:ih:carb01#linkert_model_m_and_dc_carbs_1965_and_earlier|Linkert Carb Basic Information]] |
| - | * [[techtalk:ih:carb01b|Bendix Carb Identification]] | + | * [[techtalk:ih:carb01a|Linkert Carb Identification]] |
| + | * [[techtalk:ih:carb01b|Rebuilding the Linkert Carb]] | ||
| - | ====== Bendix Carb Rebuilding / Refreshing ====== | + | ====== Float Bowl ====== |
| + | There is a brass baffle in the DC-7 float bowl on the left in the pic below. The DC-12 (right) does not have one. \\ | ||
| + | The baffle helps arrest an rare-ish annoying Linkert trait. \\ | ||
| - | If you placed the plunger in the Taiwanese rebuild kit next to the stock part, the Taiwanese part is much longer. \\ | + | If your moving at high speed and you grab all the binders you can in order set up for a tight corner; ((Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/163968-another-linkert-dc-carb-question?t=1762899)) \\ |
| - | This in turn can cause the plunger to 'bottom' in the bowl and it can get stuck as in when at W.O.T. \\ | + | The fuel sloshes to the front of the bowl opposite of the bowl vent tube. \\ |
| - | It actually can bottom before the butterfly is fully opened. \\ | + | As you stand the bike back up and peg the throttle (wot), the fuel now sloshes over to the opposite end of the float chamber. \\ |
| - | You can use most of the parts in this kit but purchase the Harley Part (#27762-71TA). \\ | + | (where it enters the top of the vent tube and exits the carb (spraying the rider, you will smell it). \\ |
| - | Aftermarket rebuild kit: \\ | + | In extreme cases, if your hanging off the right side of bike, you can get a face full of hi-test. \\ |
| - | {{:techtalk:ih:carb:bendix_carb_and_parts_by_schutzhund9.jpg?direct&300|}} ((photo by Schutzhund of the XLFORUM )) \\ | + | |
| - | ===== Cleaning ===== | + | {{:techtalk:ih:carb:dc7-dc12_carb_bowls_by_doc308.jpg?direct&300|}} ((photo by Doc308 of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/163968-another-linkert-dc-carb-question?t=1762899)) \\ |
| - | * The general appearance of the inside of the carb is not necessarily a good indication of its condition. \\ It can look spotless and have clogged jets, or look cruddy and have clear jets. | + | |
| - | * It's good to clean each individual part rather than soak or boil the whole carb in carb cleaner. \\ But either way is good. Do not allow any solvents to contact any rubber parts (tip of needle, O-ring seal for bowl). | + | |
| - | * Make sure to take everything apart, jets, needle, accel pump, all rubber components especially. | + | |
| - | * Examine all parts for excessive wear, damage, distortion, etc. | + | |
| - | * Cleaning solutions/sprays vary based upon your location, needs, budget, preferences and quality. \\ Dismantle the carb down to the body before soaking. You will be surprised at all the dirt in the bottom of the soaking container. \\ Here are some helpful ideas: | + | |
| - | * An overnight soak in a solution of Pinesol and water followed up with a good brush down with a toothbrush then rinse and air dry. ((http://www.hotrodders.com/forum/pinesol-really-does-clean-carburetors-amazingly-pics-inside-248810.html)) | + | |
| - | * A 20 minute to up to a few days soak in a gallon of Gunk (or other) Carburetor Cleaner that has a basket inside for small parts and lowers in the can with a handle, rinse, air dry, use. | + | |
| - | * Soak it in mineral spirits for a few days. ((Monte03 of the XLFORUM http://xlforum.net/forums/showthread.php?t=185361)) | + | |
| - | * You can use acrylic paint thinners for cleaning up carb parts. It melts the fuel varnish right off. ((russzx6 of the XLFORUM http://xlforum.net/forums/showthread.php?t=185361)) | + | |
| - | * An aerosol spray carb cleaner will also work but may not loosen all of the build up in the jets or orifices in the carb body if they're not directly sprayed through. | + | |
| - | * Blow out all holes, jets and orifices thoroughly with compressed air after cleaning. | + | |
| - | A gallon of carburetor cleaner is very useful in cleaning out varnish from the channels and metering chamber. \\ | + | ====== Needle Seat ====== |
| - | It is especially useful for soaking stuck gaskets between parts and loosen the joint between them for dis-assembly. \\ | + | Determine if you have DC1 or DC2 inlet seat (these have one "window"). \\ |
| - | Depending on how old or how 'stuck' the parts are, soaking for a couple hours may help to separate the old gasket in between. \\ | + | |
| - | Make sure to remove any rubber or plastic parts before soaking. Also check the label for safety precautions. \\ | + | |
| - | Parts that have been sitting for years may have to be soaked for about 24 hours or even days. \\ | + | |
| - | | Carburetor Cleaner ((photo by Hippysmack)) || | + | |
| - | |{{techtalk:ref:genmsr:parts_cleaner_1_by_hippysmack.jpg?direct&300|}}|{{techtalk:ref:genmsr:parts_cleaner_2_by_hippysmack.jpg?direct&300|}}| | + | |
| - | **Note**: \\ | + | {{:techtalk:ih:carb:linkert_mod_1_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) {{:techtalk:ih:carb:linkert_mod_2_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) \\ |
| - | The use of wire to 'rod' out jets and orifices is discouraged in the FSM. \\ | + | |
| - | However, a hard wire such as a welding tip cleaner, has been known to open up stubborn areas at times. \\ | + | |
| - | Always use a wire smaller than the orifice cleaned so you don't widen the holes. \\ | + | |
| - | Doing so could create burrs or change the hole sizes. \\ | + | |
| - | **Carb Stand**: \\ | + | If so you need to open the second window as the DC6,7,10 and 12 have. \\ |
| - | * You can put the carb in a vice to remove the screws, and for much of the following work. \\ Wrap in a shop towel; close the vice gently taking extra care with the choke and throttle linkages. \\ The vice is a needed extra pair of hands. | + | |
| - | * It can be very confusing trying to decide which way to bend the tang if it is not correct. \\ If the fuel level is low,Is the float high or low?, Do you need to bend the tang up or down? etc. \\ On the bench the carb is usually upside down, adding to the confusion. You should sort all this out before making an adjustments. | + | |
| - | However, this setup works better than putting the carb directly into the vice. \\ | + | {{:techtalk:ih:carb:linkert_mod_3_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) {{:techtalk:ih:carb:linkert_mod_4_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) \\ |
| - | The carb is set upright as 'in use' making adjustments more straight forward. \\ | + | |
| - | {{:techtalk:ref:tools:carb_stand_1_by_ironmick.jpg?direct&150|}} ((photo by IronMick of the XLFORUM http://xlforum.net/forums/showthread.php?t=185361)) | + | |
| - | {{:techtalk:ih:carb:bendix-zenith_carb_12_by_the_doctor71_of_the_xlforum.jpg?direct&200|}} | + | |
| - | ((Pic courtesy of The Doctor71 of the XLFORUM)) \\ | + | |
| - | ===== Main Jet / IdleTube ===== | + | |
| - | ==== Main jet ==== | + | |
| - | The main jet screw is the one closest to the air cleaner. The Idle screw is closer to the manifold. \\ | + | If so, then you can cut a second window in the seat. \\ |
| - | The main jet doubles as the float bowl securing bolt under the carb. \\ | + | |
| - | **Fixed or adjustable main jet identification**: \\ | + | {{:techtalk:ih:carb:linkert_mod_5_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) {{:techtalk:ih:carb:linkert_mod_6_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) {{:techtalk:ih:carb:linkert_mod_7_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) \\ |
| - | The factory Bendix carbs for Sportsters have a fixed main that doubles as the float bowl bolt with the Idle tube on top. \\ | + | |
| - | For a quick visual, look at the top of the carb, first screw boss from the A/C, look for either a welch plug or a screw head with no spring under it. \\ | + | {{:techtalk:ih:carb:linkert_mod_8_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) {{:techtalk:ih:carb:linkert_mod_9_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) {{:techtalk:ih:carb:linkert_mod_11_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) \\ |
| - | The screw head looks like it could be adjusted but it is not the adjustable type. ((fergerburger of the XLFORUM http://xlforum.net/forums/showthread.php?t=988224&page=2)) \\ | + | |
| - | The later 'Zenith' Carb with the adjustable main has a screw that goes thru a spring. \\ | + | {{:techtalk:ih:carb:linkert_mod_12_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) {{:techtalk:ih:carb:linkert_mod_13_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) {{:techtalk:ih:carb:linkert_mod_14_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) \\ |
| - | The spring is visible looking at the top of the carb, first screw boss from the A/C. \\ | + | |
| - | It is the main adjustment that has a tapered point at the end. \\ | + | |
| - | * Turning clockwise = leaner. | + | |
| - | * Turning counter-clockwise = richer. | + | |
| - | ==== Adjustable main jet conversion ==== | + | {{:techtalk:ih:carb:linkert_mod_15_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) {{:techtalk:ih:carb:linkert_mod_16_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187)) \\ |
| - | === Sub Documents === | + | |
| - | * [[techtalk:ih:carb05b|Installing the Adjustable Main Jet Kit]] | + | |
| - | Some say not to do this as an adjustable main jet is too easy to inadvertently lean out the mix too much and burn a piston or two. ((Ivan RoachCoach of the XLFORUM http://xlforum.net/forums/showthread.php?t=988224)) \\ | + | You end up with a needle seat position (read as float level) that can be adjusted on the side of the road in seconds. \\ |
| + | Thus making the effort required to get this critical aspect of fine tuning quick and easy to dial in. \\ | ||
| - | If your certain carb is suppose to have a fixed jet but has an adjustable jet instead, it may have been modded for the adjustable jet. \\ | + | ====== Tuning ====== |
| - | For the adjustable main jet modification, the kit describes cutting a thread in the hole where the welch plug normally goes. ((DirtyHarry68 of the XLFORUM http://xlforum.net/forums/showthread.php?t=2072203&page=2)) \\ | + | ===== Adjustments per Dr Dick ===== |
| - | J&P sells the conversion kit. [[https://www.jpcycles.com/product/401-817/adjustable-main-jet-kit-for-bendix-zenith-carbs?mrkgcl=444&mrkgadid=3303098704&utm_source=bing&utm_medium=cpc&utm_term=ProductType3carburetor_jet_kits&utm_campaign=Bing+Shopping++Generic+-+Air+Intake+and+Fuel+System&utm_content=pla&creative=77172029873761&device=c&matchtype=e&msclkid=771d7df7228d13b8f16a2087deca8b9f|Adjustable Main Jet Kit for Bendix/Zenith Carbs]] \\ | + | Adjusting the idle mixture screw critical. ((Dr Dick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/179861-factory-carburetors/page4?t=1932694&page=4)) \\ |
| - | J&P Cycles Part Number: 401-817, Manufacturer Part Number: 35-0202 \\ | + | Most will make both adjustments in concert so the bike idles with the least throttle plate opening. \\ |
| - | * Establishes full adjustability for Bendix and Zenith carb main and idle circuits | + | Rarely does this give good manners other than idling in the driveway. \\ |
| - | * No need to stock several and expensive fixed jets | + | |
| - | * Requires special tap 400-966 for installation | + | |
| - | * Kit includes main jet, fiber washers, idle jet and control spring | + | |
| - | ==== Idle Tube ==== | + | The bigger picture regarding these adjustments - for this the throttle plate must be: \\ |
| - | Alternate references include intermediate / idle / low speed jet. The original idle tubes are designated with either | + | * Positioned (milled notch up & facing air cleaner) |
| + | * Registered correctly (even peripheral contact to throttle body at fully closed) | ||
| - | The "needle" is just a transfer tube to get low speed mix from the bottom of main up to the top side of the carb to the idle/low speed circuitry. ((CHOPTOP37 of the XLFORUM http://xlforum.net/forums/showthread.php?p=4829064#post4829064)) \\ | + | Removing the brass screw plug near idle mix screw exposes the idle well. \\ |
| - | The tube is a pretty sloppy fit where it enters the top of the carb, below the threads. \\ | + | On the side wall of the well, you will see a hole that feeds mixture (not fuel) to the idle mix screw. \\ |
| - | There is a built in air bleed circuit between the idle tube passage and idle mixture circuit. \\ | + | Mixture that enters this hole is regulated by the adjuster screw and discharged into air the stream thru a hole drilled close to intake manifold. \\ |
| - | It's location of the idle air bleed allows less fuel flow during time of open throttle plate high reversion compared to the other OEM carbs. ((Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1770307&page=5)) \\ | + | This supplies most of the idle mixture. |
| - | Translation: it's the bleed that allows the Bendix to tolerate straights better. \\ | + | |
| - | The Idle Tube on top of 72-74 OEM carbs is a brass flat top screw that screws thru a fiber washer down thru the top into that fixed main jet (all non adjustable). \\ | + | Then on the floor of the well, you will see a series of 4 tiny holes. These are the transition holes. \\ |
| - | From 1972-1974, the idle tube was exposed on top of the carb with a brass screw for installation. \\ | + | The remainder of idle mixture comes from the 1st (one closest to manifold) transition hole as it's open to low manifold pressure. \\ |
| - | {{:techtalk:ih:carb:72-74_bendix_idle_tube_by_jayd142.jpg?direct&300|}} ((photo by jayd241 of the XLFORUM http://xlforum.net/forums/showthread.php?p=4911522)) {{:techtalk:ih:carb:72-74_bendix_idle_tube_location_by_the_doctor71_annotated_by_hippysmack.jpg?direct&300|}} ((photo by The Doctor71 of the XLFORUM http://xlforum.net/forums/showthread.php?t=2072203&page=2)) | + | The other 3 are open to the higher atmospheric pressure because they are on the other side of throttle plate at idle. \\ |
| + | That means lots of air enters the well thru the 3 hi pressure holes. All that air dilutes the fuel into a 'mixture'. \\ | ||
| - | The idle tube on 75-E76 carbs is pressed into the body with a welch plug covering it. \\ | + | Because the idle mix screw adjusts the flow of this mixture a funny thing happens as you richen it. \\ |
| + | Because the air component is so much less dense than the fuel component, the mix screw is less a restriction to the air than to the fuel. \\ | ||
| + | It gets to a point where opening it adds more air then it does fuel. In other words it will only get so rich no matter how far you back it out. \\ | ||
| + | This is a DC Linkert anomaly because 4 holes spread over a very large throttle plate swing bleed a lot of air into the well on idle. \\ | ||
| - | Zenith/Bendix offered (and still does) aftermarket carbs with an adjustable main which replaced the brass idle tube (screw closest to the cleaner). \\ | + | Things change as soon as you begin opening throttle plate. \\ |
| - | This screw in tube with the small spring actually doubles as an idle tube to pick up fuel up to the idle circuit. \\ | + | Now the number of transition holes open to low pressure is larger and the number open to atmospheric pressure is less (ie: the air component of the mixture drops). \\ |
| - | But the taper at the end of it is to adjust the main circuit. \\ | + | Now the idle mix screw is controlling a more fuel laden mixture. \\ |
| - | The size / markings / pilot orifice of the adjustable idle tube is not known. ((CHOPTOP37 of the XLFORUM http://xlforum.net/forums/showthread.php?p=4829064#post4829064))) \\ | + | |
| - | But you could use a pin gauge or drill bit to measure should you feel the need to work on this circuit. \\ | + | |
| - | Keep in mind the adjustable main's biggest job is it blocks or opens the main circuit with the taper at the end. ((CHOPTOP37 of the XLFORUM http://xlforum.net/forums/showthread.php?p=4829064#post4829064))) \\ | + | |
| - | The rest of the tube / orifice has nothing to do with that. That is for the low speed. \\ | + | |
| - | Like any adjustable jet, you cannot over tighten it clockwise or you can indent the taper. \\ | + | |
| - | The later adjustable main is favorable if mounting on an early magneto motor as you do not have to pull the carb off to make main adjustments. \\ | + | |
| - | Check the idle tube for cracks. This one doesn't look cracked unless you look at it close up. \\ | + | The ratio of air to fuel continuously drops as you open the throttle until the last holes is on downstream of the plate. \\ |
| - | {{:techtalk:ih:carb:cracked_idle_tube_2_by_jbueno26.jpg?direct&300|}} ((photo by jbueno26 of the XLFORUM http://xlforum.net/forums/showthread.php?t=2010147)) {{:techtalk:ih:carb:cracked_idle_tube_1_by_jbueno26.jpg?direct&300|}} ((photo by jbueno26 of the XLFORUM http://xlforum.net/forums/showthread.php?t=2010147)) | + | The mix screw will have a larger effect on low throttle running than idling. You need to set the screw where you get good around town manners. \\ |
| + | Then adjust the speed screw to the appropriate speed. \\ | ||
| + | This is a delicate balancing act that will change as the properties of the air change: temperature, pressure (altitude or barometer), and water content (humidity). \\ | ||
| + | The DC is prone to this fickleness due to the large air bleed variation at different throttle plate positions. \\ | ||
| - | ===== Accelerator Pump ===== | + | The S&S carbs based on the DC Linkert used only two transition holes in the early years and three later on. \\ |
| + | Both show a marked improvement in weather stability. \\ | ||
| - | There are 3 holes in the accelerator pump shaft to provide more or less fuel upon acceleration. \\ | + | ==== Adjusting the Linkert DC ==== |
| - | Install the pump shaft pin in the bottom hole for richest setting or the top hole for the leanest setting. \\ | + | ^Carb Idle Speed^ |
| + | |Adjust until engine idles and runs smoothly| ((Clymer Sportster Repair Manual 1959-1985)) | ||
| - | In some of the new kits, you may find the accelerator pump is slightly too long as in the pic below. ((The Doctor71 of the XLFORUM http://xlforum.net/forums/showthread.php?p=5519420#post5519420)) \\ | + | * A properly adjusted carburetor requires little re-adjustment according to the FSM. It shouldn't be necessary to change the adjuster of the low speed needle more than 1/8 turn or the high speed adjuster more than 1/4 turn richer or leaner to obtain correct mixture for a change in altitude unless there are some worn or obstructed parts to consider.((1959-1969 HD Sportster FSM)) |
| - | The throttle could hang up at about 90% (the bracket mechanism might hang up on the shaft, if the shaft is too long). \\ | + | * Before attempting to correct faulty engine performance through carb adjustment, eliminate all other possible causes for poor engine performance such as bad spark plugs, poor timing, mal-adjusted tappets, dirty air cleaner, leaking gaskets and poor manifold connections.((1959-1969 HD Sportster FSM)) |
| - | Fortunately the solution is fairly simply. Take a dremel tool and trim the top about 1/16" - 1/8" or so and bevel the edges. \\ | + | * The fuel/ air mixture for low engine speed is regulated by the low speed needle only. The fuel supply for high speed is regulated by a combination of the adjustable needle and the fixed jet (which dominates the regulation of high speed fuel supply). The high speed needle provides a supplement, to a degree, of the fuel supplied by the fixed jet when it is found that slightly enrichening the mixture improves engine performance. ((1959-1969 HD Sportster FSM)) |
| - | Click on a pic to enlarge: \\ | + | |
| + | <blockquote> | ||
| + | * Both, high speed and low speed, needles turn inward (clockwise) for leaner or outward (counterclockwise) for richer mixtures at the respective speeds for which they adjust. | ||
| + | * Adjust idle (low speed): Make sure the carb control wire is adjusted so the throttle lever fully closes and opens with handlebar movement.((1959-1969 HD Sportster FSM)) | ||
| + | * Turn both the high and low needles all the way in (clockwise) to a light seat position but do not close off either too tight as it may damage needle and/ or seat. ((1959-1969 HD Sportster FSM)) | ||
| + | * Turn low speed needle out app. 1 1/2 turns (in this position, engine will start but low speed idle will probably be too rich).((1959-1969 HD Sportster FSM)) | ||
| + | * Start the engine, let it reach operating temp, choke off (open) then correct the position of the low speed needle. Turn the low speed needle in (clockwise) 1/8 turn at a time until engine leans out and misses and is inclined to stop. Then, back low speed needle out 1/8 turn at a time (allow a few seconds in between turns to allow engine to adjust) until engine hits regularly with spark advanced, throttle closed and engine running at idle speed. Starting and all around performance will be better with low speed adjustment slightly rich, rather than lean. ((1959-1969 HD Sportster FSM)) | ||
| + | * Adjust throttle lever stop screw as needed to make engine idle at proper speed with throttle fully closed. Turn screw clockwise for faster or counterclockwise for slower idle speed. Be careful not to idle engine at the slowest possible speed because an extreme low idle position will cause hard starting. Changing the idle speed with the throttle screw may also alter the low speed fuel/ air mixture so remember to go back and check that adjustment and correct if needed using the above method.((1959-1969 HD Sportster FSM)) | ||
| + | * Turn high speed needle out app. 3/4 turns. Check high speed adjustment by running the motorcycle on the road at various speeds between 20 mph and max speed with spark fully advanced. Re-adjust high speed needle until optimum performance is achieved. Best all around engine performance can usually be found with the high speed needle set between 3/4 and 1 1/2 turns out (open). ((1959-1969 HD Sportster FSM)) | ||
| + | </blockquote> | ||
| + | * The FSM may be of little use from this point on. | ||
| + | * Its trial and error now to find out what works for you. Idle speed is critical in easy starting. Low idle can make bikes difficult to start and too high is uncomfortable at stops. There is a sweet spot in there somewhere that you must find. 1200 rpm is a good speed to begin your fine tuning. ((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/179861-factory-carburetors/page3?postcount=31#post3850086)) | ||
| + | * When it's warm and it's been off for a minute. I only need to push the kicker through and it starts up. If it's been off for a bit, the first kick without retarding the mag results in a locked up kicker, feeling there is a fuel charge sitting in the combustion chamber. The idle adjustment screw can be backed out as far as I want and it doesn't change much at all. If I go too lean, it will stumble of course. If the idle adj. screw is 1/8th out from stumble as the manual suggests, I have a hard time with starting. ((Zaemo of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/179861-factory-carburetors/page3?postcount=31#post3850086)) | ||
| + | * The bigger picture regarding these adjustments for this the throttle plate must be: Positioned (milled notch up & facing air cleaner) and registered (even peripheral contact to throttle body at fully closed) correctly.((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/179861-factory-carburetors/page3?postcount=31#post3850086)) | ||
| + | * Removing the brass screw plug near idle mix screw exposes the idle well. On the side wall of the well you will see a hole that feeds mixture (note that I didn't say fuel) to the idle mix screw. Mixture that enters this hole is regulated by the adjuster screw, and discharged into air stream thru a hole drilled close to intake manifold. This supplies most of the idle mixture.((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/179861-factory-carburetors/page3?postcount=31#post3850086)) | ||
| + | * Then on floor of the well you will see a series of 4 tiny holes. These are the transition holes. The remainder of idle mixture comes from the 1st (one closest to manifold) transition hole as its open to low manifold pressure. The other 3 are open to the higher atmospheric pressure because they are on the other side of throttle plate at idle. That means lots of air enters the well thru the 3 hi pressure holes. All that air dilutes the fuel into a 'mixture'. Because the idle mix screw adjusts the flow of this mixture a funny thing happens as you richen it. Because the air component is so much less dense than the fuel component the mix screw is less a restriction to the air than to the fuel- its gets to a point where opening it adds more air then it does fuel. In other words it will only get so rich no matter how far you back it out. This is a DC Linkert anomaly because 4 holes spread over a very large throttle plate swing bleed a lot of air into the well on idle. Things change as soon as you begin opening throttle plate. Now the number of transition holes open to low pressure is larger and the number open to atmospheric pressure is less. ie: the air component of the mixture drops. Now the idle mix screw is controlling a more fuel laden mixture. The ratio of air to fuel continuously drops as you open the throttle until the last holes is on downstream of the plate. The mix screw will have a larger effect on low throttle running than idling. You need to set screw where you get good around town manners and then adjust the speed screw to the appropriate speed.((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/179861-factory-carburetors/page3?postcount=31#post3850086)) | ||
| + | * This is a delicate balancing act that will change as the properties of the air change: temperature, pressure (altitude or barometer), and water content (humidity). The dc is prone to this fickleness due to the large air bleed variation at different throttle plate positions.((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/179861-factory-carburetors/page3?postcount=31#post3850086)) | ||
| + | * The S&S carbs based on the DC Linkert used only two transition holes in the early years and three later on. Both show a marked improvement in weather stability.((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/179861-factory-carburetors/page3?postcount=31#post3850086)) | ||
| - | | Shaft is too long. ((photo by The Doctor71 of the XLFORUM http://xlforum.net/forums/showthread.php?p=5519420#post5519420)) || Trimmed version. ((photo by The Doctor71 of the XLFORUM http://xlforum.net/forums/showthread.php?p=5519420#post5519420)) | | + | |
| - | |{{:techtalk:ih:carb:bendix_accelerator_pump_1_by_the_doctor71.jpg?direct&200|}}|{{:techtalk:ih:carb:bendix_accelerator_pump_3_by_the_doctor71.jpg?direct&200|}}|{{:techtalk:ih:carb:bendix_accelerator_pump_2_by_the_doctor71.jpg?direct&200|}}| | + | * These carbs are extremely touchy to float level at just off idle throttle positions. Problems show as spitting / coughing on one end of the spectrum to burbiling / stumbling at the other end. Many owners will report how precise you need to be with float levels to get your bike to run as a fine watch.These guys also eventually learn two things:((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187&highlight=linkert)) |
| + | - Float levels will rise on their own due to the steel inlet needle wearing the brass seat away. This is a mileage thing-- just like tire and chain wear (steel needle carbs only- linkert, orig earlies and orignal L's). ((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187&highlight=linkert)) | ||
| + | - Secondly and more importantly, these carbs are very susceptible to errant low speed metering as fuel composition, barometric pressure, humidity, and air temperature vary. Trying to hit the sweet spot requires many float adjustments, idle mixture settings, idle speed settings and road tests. To do away with that wasted time and aggravation, I fit all my side bowl carbs with an externally adjustable float level. Now I can change float level on a whim.((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/186391-linkert-dc-mods-pull-throttle-choke-performance?t=1993187&highlight=linkert)) | ||
| - | In the first pic below, the left one below is the original accelerator pump as it came from the factory in 1974. \\ | + | ====== Links,Parts and Services for Linkert Carbs ====== |
| - | Middle is from the new rebuild kit. On the right, is the accelerator pump (27762-71TA) as purchased from a local HD dealer. \\ | + | |
| - | The middle unit is the problem item. The upper section, the piece above the roll pin, is too long. \\ | + | |
| - | The second pic below is the after pic. The middle unit, has had the upper section of the shaft trimmed down. Good to go now. \\ | + | |Carb Assembly is HD Part Number: 27155-57B((1959-1969 HD Sportster FSM))|||| |
| - | Rub some oil onto the umbrella before installing it. ((Pan55 of the XLFORUM http://xlforum.net/forums/showthread.php?p=4655603&highlight=bendix#post4655603)) \\ | + | ^Model \\ (marked on carb)|Idle Port Hole \\ Drill Sizes^Model \\ (marked on carb)|High Speed Hole \\ Drill Sizes| |
| - | This makes sure it sets itself instead of binding / deforming in the first few uses (also insures smooth operation). \\ | + | |DC-1, 1L, 1M, 10 \\ DC-2|#70 (0.028 in) \\ #56 (0.0465 in)|DC-1, 1L, 1M, 10, 6, 7, 12 \\ DC-2|#55 (0.052 in) \\ #70 (0.028 in)| |
| - | Also look down inside the bore of the acc pump and make sure there isn't any residue scale. \\ | + | |
| - | {{:techtalk:ih:carb:bendix_accelerator_pump_4_by_the_doctor71.jpg?direct&200|}} ((photo by The Doctor71 of the XLFORUM http://xlforum.net/forums/showthread.php?p=5519420#post5519420)) {{:techtalk:ih:carb:bendix_accelerator_pump_5_by_the_doctor71.jpg?direct&200|}} ((photo by The Doctor71 of the XLFORUM http://xlforum.net/forums/showthread.php?p=5519420#post5519420)) \\ | + | ===== Links to Carb Diagrams and Parts ===== |
| + | |||
| + | * [[http://www.linkertcarbs.com/| Linkert Carbs.com]] | ||
| + | * [[http://linkertcarbs.com/linkertgaskets.html|Into The Wilderness Trading]] | ||
| + | * [[https://www.demonscycle.com/manuals_diagrams|Demons Cycle website of useful manuals]] | ||
| - | Add this spring to your accelerator pump if you don't have it. It will pull the butterfly closed when you let off and give the throttle a good feel. \\ | ||
| - | {{:techtalk:ih:carb:bendix_acc_pump_spring_by_wirenut.jpg?direct&300|}} ((photo by wirenut of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639&page=2)) \\ | ||
| - | |||
| - | ==== Welch Plug or Expansion Plug ==== | ||
| - | |||
| - | * Inspection: | ||
| - | * A close inspection around the walls of a welch plug can reveal possible leaks. | ||
| - | * Removal: ((HD Service Bulletin #518 dated September 10, 1965 pg OC-189)) | ||
| - | * Whenever a welsh plug is removed, a new one should be installed in it's place, especially since a large part of the time, removal of one means destroying or deforming it.((1959-1969 HD Sportster FSM)) | ||
| - | * Drill an 1/8" hole thru it (just deep enough to break thru to the other side) off center and pry it out with a small punch. Be careful not to drill too deep which could destroy the nozzle assembly or casting. While prying it out, be careful not to damage the casting counter-bore edges around the plug. | ||
| - | * You can also drill a small hole in it and use a small tap just big enough to start in the hole. ((snake173 of the XLFORUM http://xlforum.net/forums/showpost.php?p=3646523&postcount=1)) \\ Thread the tap in the hole. \\ When it gets to the bottom of the passage, it will force the valve out with out damaging the bottom of carb passage. \\ Make sure to clean all the chips out to keep from plugging up passages later. | ||
| - | * Installation: ((HD Service Bulletin #518 dated September 10, 1965 pg OC-189))((1959-1969 HD Sportster FSM)). | ||
| - | * The plug should be seated with a flat end punch that is slightly smaller than the diameter of the plug. The plug should be flat and not concaved to assure a tight fit. If leakage is suspected due to a rough or damaged welch plug seat in the casting, apply a small amount of epoxy or suitable sealant to the edges after installing it. | ||
| - | * Installation Recommendations from Hubbard Spring [[http://www.hubbardspring.com/install_reco.php?cid=45]] | ||
| - | * Some Welch Plug dims: [[http://www.hubbardspring.com/index.php/category/43/cupped-plugs-and-cupped-plugs-pierced-catalog]] | ||
| - | |||
| - | ===== Float ===== | ||
| - | ==== Sub Documents ==== | ||
| - | See also [[techtalk:ih:carb05a|Installing Bendix Float Spring]]. \\ | ||
| - | |||
| - | ---- | ||
| - | |||
| - | The spring should not be stretched or distorted. \\ Inspect the needle valve cone point for wear and scratches. ((1970-1976 HD Sportster FSM pg3-46)) \\ | ||
| - | |||
| - | {{:techtalk:ih:carb:bendix_float_and_spring_4_by_dirtyharry68.jpg?direct&300|}} ((photo by DirtyHarry68 of the XLFORUM http://xlforum.net/forums/showthread.php?t=2072203&page=7)) {{:techtalk:ih:carb:bendix_pic_15_by_piniongear.jpg?direct&300|}} ((drawing by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?threadid=941501&page=3)) \\ | ||
| - | |||
| - | ===== Choke Plate \ Cable ===== | ||
| - | |||
| - | Before cranking the engine, the throttle should be opened to expose all three idle holes (top inside the venture). ((1970-1976 HD Sportster FSM pg3-48)) \\ | ||
| - | The choke should be fully closed when cranking the engine and slightly opened after the engine starts. \\ | ||
| - | The hole in the choke plate helps to prevent over-choking when the engine is started. \\ | ||
| - | It should be moved to wide open when the engine is patially warmed up. \\ | ||
| - | Here is a pic of what the installation of the choke/throttle butterfly looks like. The small hole/cutout is at the top. ((piniongear of the XLFORUM http://xlforum.net/forums/showpost.php?p=3171560&postcount=16)) \\ | ||
| - | {{:techtalk:ih:carb:bendix_pic_3_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showpost.php?p=3171560&postcount=16)) \\ | ||
| - | |||
| - | The throttle butterfly in the main body opens to the manifold. ((brianbbs67 of the XLFORUM http://xlforum.net/forums/showthread.php?t=1770307&page=2)) \\ | ||
| - | When it's shut, no throttle, you should be able to hold the intake side of the carb up to the light and not see anything around it showing light. \\ | ||
| - | If it does, it's out of round and hard to fix as it leans out the mix. \\ | ||
| - | |||
| - | **Adjusting the choke cable**: \\ | ||
| - | Push the knob all the way in, have the choke wide open, tighten set screw on the cable. ((egarrett of the XLFORUM http://xlforum.net/forums/showthread.php?t=2022848&page=3)) \\ | ||
| - | |||
| - | ===== Throttle Cable ===== | ||
| - | If you have a twist grip throttle (barrel type) you are not going to be able to use hard wire. The bellcrank on your carb makes the cable end swing in an arc. \\ | ||
| - | You may want to bend the end of the bracket just a bit upwards to lessen the binding at closed throttle. \\ | ||
| - | As you open the throttle the cable becomes more inline with the housing and binding becomes less and less. | ||
| - | The butterfly is going to go and stay where the cable tells it to go. ((piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?p=3446817#post3446817)) \\ | ||
| - | |||
| - | The cable can bind with the hard wire throttle. The sketch below is exaggerated but it will give you a general idea of what can bind when the throttle is opened. \\ | ||
| - | The cable is straight and the bell crank on the carb turns in a circular motion around the pivot point of the butterfly shaft. \\ | ||
| - | {{:techtalk:ih:carb:bendix_throttle_cable_mech_by_piniongear.jpg?direct&400|}} ((drawing by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?p=3446817#post3446817)) \\ | ||
| \\ | \\ | ||
| - | One solution was to fabricate a cable holder that was able to rotate slightly as the angle of the cable changed. ((piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?p=3446817#post3446817)) \\ | ||
| - | This has a bronze ball inside the capping pieces which rotates as the cable moves around. \\ | ||
| - | The bracket is mounted to the back side of the manifold (towards the center of the frame). \\ | ||
| - | The ball is threaded and into that screws the cable housing stop fitting. \\ | ||
| - | So as the angle changes, the ball swivels and so does the end of the cable housing allowing the cable not to bend or get pinched. \\ | ||
| - | These were made out of a pair of Quik Fasteners. Two halves go around a round brass ball. \\ | ||
| - | This allows the housing to rotate as the throttle is opened and closed. \\ | ||
| - | |||
| - | {{:techtalk:ih:carb:bendix_throttle_cable_mod_1_by_piniongear.jpg?direct&300 |}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?p=3446817#post3446817)) {{:techtalk:ih:carb:bendix_throttle_cable_mod_2_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?p=3446817#post3446817)) {{:techtalk:ih:carb:bendix_throttle_cable_mod_3_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639)) \\ | ||
| - | |||
| - | Another simple way for the internal throttle setup: ((Monte03 of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639&page=4)) \\ | ||
| - | Fab a 90° bracket that is mounted off the top manifold bolt. \\ | ||
| - | Then purchase an HD cable clamp (9994) and route the cable through the left side and adjust so that its inline with carb swivel. \\ | ||
| - | The 9994 is the same factory clamp as used for a magneto cable (disregard the spring shown, it's not needed) \\ | ||
| - | |||
| - | {{:techtalk:ih:carb:throttle_cable_1_by_monte03.jpg?direct&300|}} ((photo by Monte03 of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639&page=4)) {{:techtalk:ih:carb:throttle_cable_2_by_monte03.jpg?direct&300|}} ((photo by Monte03 of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639&page=4)) \\ | ||
| - | |||
| - | If you're using a braided cable, it needs a return spring on the butterfly. If you do not, then that will result in high revs when you blip the throttle. ((piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?p=3446817#post3446817)) \\ | ||
| - | The hard wire is what opens and closes the butterfly. The braided cable cannot close the butterfly because the cable is not stiff enough. \\ | ||
| - | Even if you find broken strands, be sure to rig up a spring. It wont take a great deal of spring tension to close the butterfly, but a spring is needed. \\ | ||
| - | |||
| - | If the cable is that shot, replace it. But if just the ends are frayed, you can solder them together with electronics solder. ((Monte03 of the XLFORUM http://xlforum.net/forums/showthread.php?t=596371)) \\ | ||
| - | Start by cleaning it with alcohol (cleans great and leaves no residue). ((wickit of the XLFORUM http://xlforum.net/forums/showthread.php?t=596371&page=3)) \\ | ||
| - | After this if it is frayed get some small wire (30 AWG). Use this to wrap the end of your cable so all of the strands are contacting each other. \\ | ||
| - | (gets rid of the birdcage look). Apply flux, add heat and solder. \\ | ||
| - | When the solder flows into the strands remove the heat, let it cool and remove any excess solder with a file. \\ | ||
| - | |||
| - | {{:techtalk:ih:carb:bendix_carb_by_jdxlch.jpg?direct&300|}} ((photo by jdxlch of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639)) {{:techtalk:ih:carb:bendix_throttle_spring_by_russ_t_nail.jpg?direct&300|}} ((photo by Russ t nail of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639&page=5)) \\ | ||
| - | |||
| - | Below, the existing bracket was modified. With two crescent wrenches and a rat tail file, the hole was enlarged almost to the end of the support. ((jdxlch of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639&page=2))\\ | ||
| - | Make sure to get it out far enough to clear the throttle shaft cam. The bracket was put in a vise and to bend the very end up and in to about 45°. \\ | ||
| - | Using the two crescents, one on each side of the cable sleeve, it and just rolled it back. \\ | ||
| - | Be careful not to pry / push on the cable sleeve. It's only rolled over on the bottom like a rivet. \\ | ||
| - | Next, the bracket was positioned in the vise and the cresents were used to open up the existing 90° bend another 45°. \\ | ||
| - | You may have to tweek it a bit to get the straightest throw for the cable. \\ | ||
| - | |||
| - | {{:techtalk:ih:carb:bendix_throttle_cable_mod_1_by_jdxlch.jpg?direct&300|}} ((photo by jdxlch of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639&page=2)) {{:techtalk:ih:carb:bendix_throttle_cable_mod_2_by_jdxlch.jpg?direct&300|}} ((photo by jdxlch of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639&page=2)) {{:techtalk:ih:carb:bendix_throttle_cable_mod_3_by_jdxlch.jpg?direct&210|}} ((photo by jdxlch of the XLFORUM http://xlforum.net/forums/showthread.php?t=1069639&page=2)) \\ | ||
| - | |||
| - | The single set screw on this cable assembly has nothing but the cable to tighten against. \\ | ||
| - | A single screw to clamp the cable not only kinks it, but also causes the braid to separate somewhat. \\ | ||
| - | This mod was done to be able to clamp the cable and minimize damage to the cable. \\ | ||
| - | |||
| - | If you used a set screw on either side of the cable, both would tighten on the cable and keep it more centered. \\ | ||
| - | The cable below is a hard wire but may also work on braided cables if you have the room. \\ | ||
| - | However, for this, a metal dowel was installed in the housing side opposite the set screw. \\ | ||
| - | This allowed the set screw to tighten solid against something hard with the cable in between (same as a double set screw). \\ | ||
| - | The dowel is on the bottom side and the set screw is on top side in the pic below. \\ | ||
| - | {{:techtalk:ih:carb:throttle_cable_mod_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?t=1480481&page=2)) \\ | ||
| - | |||
| - | |||
| - | ===== Carb Flange ===== | ||
| - | |||
| - | There are 2 small holes in the carb to manifold flange (as viewed on the outside). \\ | ||
| - | Those holes are factory drilled as part of the manufacturing process and serve no further purpose. ((Wooley of the XLFORUM http://xlforum.net/forums/showthread.php?t=941501&page=5)) \\ | ||
| - | When mounted against the manifold, they would be blocked anyway. \\ | ||
| - | The small hole was used for cross drilling the air runner boss then through drilled from the top of body for the idle mixture screw. \\ | ||
| - | Some flange gaskets have cutouts for these holes and some do not. Don't worry about them as you can use either gasket. ((Monte03 of the XLFORUM http://xlforum.net/forums/showthread.php?p=4449791&highlight=bendix#post4449791)) \\ | ||
| - | The gasket producer more than likely had a carb body to use for a guide when making the gaskets. \\ | ||
| - | |||
| - | {{:techtalk:ih:carb:bendix_pic_7_by_piniongear.jpg?direct&300|}} ((piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?t=941501&page=3)) {{:techtalk:ih:carb:bendix_intake_manifold_by_suoido.jpg?direct&200|}} ((photo by suoido of the XLFORUM http://xlforum.net/forums/showthread.php?t=1482483)) \\ | ||
| - | |||
| - | ===== Carb / A/C Brace ===== | ||
| - | The simple way to add the needed support of the carb is to use a metal brace from the A/c backing plate to the front intake lifter bolt stud at the bottom. \\ | ||
| - | |||
| - | You can make your own bracket out of 1/8”x3/4“ steel or aluminum, bent and drilled for a hole to bolt it down by the bottom of the lifters. \\ | ||
| - | Just drill the backing plate with a 1/4” drill bit and attach the carb bracket with a 1/4“-20 nut and bolt with washers. \\ | ||
| - | For the bottom of the carb bracket you can do no better than using the 'studded' lifter base bolt. \\ | ||
| - | You can make the carb bracket as a simple item or make it more complex if that suits you. \\ | ||
| - | |||
| - | This is commercial carb brace. The angle was slightly modified on this one to fit. \\ | ||
| - | {{:techtalk:ref:carb:mounting_vm-38_pic_8_by_ironmick.jpg?direct&400|}} ((photo by IronMick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1576003)) {{:techtalk:ref:carb:vm-38_project_16_by_ironmick.jpg?direct&250|}} ((photo by IronMick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1567528&page=2)) \\ | ||
| - | |||
| - | This one is made from an 1/8"x3/4" stainless steel strap. It has an aluminum spacer block between the backing plate and the brace at the top.\\ | ||
| - | {{:techtalk:ref:carb:vm-38_pic_5_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?t=1206745&page=2)) {{:techtalk:ih:carb:mounting_a_bendix_2_by_piniongear.jpg?direct&150|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?t=1206745&page=2)) \\ | ||
| - | |||
| - | |||
| - | ====== Mounting an Air Cleaner ====== | ||
| - | |||
| - | The weight of the air filter is irrelevant. All models need an air filter support. ((ryder rick of the XLFORUM http://xlforum.net/forums/showthread.php?t=2072203&page=2)) \\ | ||
| - | The manifold to head joints were never intended to support anything, and do a poor job of it. \\ | ||
| - | All bikes came from the factory with a support, the later bikes have 2. \\ | ||
| - | **NOTE**: \\ | ||
| - | There are some aftermarket supports that pick up a carb mounting bolt but they don't hold up the air filter and they act as a teeter totter. \\ | ||
| - | |||
| - | ====== Tuning ====== | ||
| \\ | \\ | ||
| - | ===== Stock Bendix (fixed jet) Tuning ===== | + | [[:techtalk:menu|{{:techtalk:gototechnicalmenu.jpg|}}]] |
| - | Before making any adjustments, bring the engine up to operating temperature. ((1970-1978 HD FSM pg 3-66)) \\ | ||
| - | Make sure the air filter is clean and that there is no leaks in the carb to manifold connection. \\ | ||
| - | |||
| - | **Low speed needle**: \\ | ||
| - | Turned in (clockwise) will lean the mixture. \\ | ||
| - | Turned out (counter-clockwise) will richen the mixture. \\ | ||
| - | The needle valve is held in position by a spring. \\ | ||
| - | Adjustment: \\ | ||
| - | Turn low speed mixture screw all the way in (clockwise) until lightly seated (do not tighten). Then; \\ | ||
| - | (72-73) Back it out (counter-clockwise) 1-1/2 turns. \\ | ||
| - | (74-E76) Back it out 2-1/4 turns. \\ | ||
| - | With the needle in this position, the engine will start but the mixture will be rich. \\ | ||
| - | |||
| - | **Throttle lever stop screw**: \\ | ||
| - | Adjust throttle lever stop screw to the engine idle at desired speed with the throttle fully closed. \\ | ||
| - | (Clockwise makes engine run faster, counterclockwise makes engine run slower. \\ | ||
| - | Never set idle adjustment to slowest possible speed. \\ | ||
| - | An extremely slow idle causes bearing wear oil consumption and slow speed acceleration problems. \\ | ||
| - | |||
| - | **Final adjustments**: \\ | ||
| - | Make final low speed needle adjustment after engine is at operating temperature (first in then out to see if the engine picks up smoothly). \\ | ||
| - | Starting and all around operation will be better when the mixture is slightly rich. \\ | ||
| - | If necessary, go back to the idle stop screw and readjust, then back to the low speed needle. \\ | ||
| - | Recommended idle speed is 700-900 RPM. \\ | ||
| - | |||
| - | During high speed operation, the fuel is metered by the fixed jet which has no adjustment. \\ | ||
| - | |||
| - | ===== Aftermarket Bendix (adjustable main jet) Tuning ===== | ||
| - | |||
| - | One advantage of using an adjustable main is being able to tune without removing the carb. ((DirtyHarry68 of the XLFORUM http://xlforum.net/forums/showthread.php?t=2072203&page=2)) \\ | ||
| - | The float bowl won’t come off without removing the carb when running a magneto. | ||
| - | |||
| - | Instructions per the "C194-19 Zenith Model 16p12 Installation Sheet (with adjustable main jet)". ((instructions provided by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?t=1294700)) \\ | ||
| - | |||
| - | As a replacement for Keihin or older Bendix, Tillotson carbs: | ||
| - | * Mount it in place of old carb using the proper studs and mounting hardware. \\ Install the vacuum tube (if applicable) or plug it off. | ||
| - | * Connect the throttle, choke and fuel line. \\ | ||
| - | * Use an inline fuel filter to minimize contamination if you don't have a screen on the petcock. | ||
| - | * Install the air cleaner. \\ | ||
| - | |||
| - | **Note**: | ||
| - | If using the chrome plated 40mm carb (014052); | ||
| - | * There is an overflow tube included with the kit. \\ The overflow tube should run away from the exhaust to the front of the bike. \\ You can use the existing overflow tube setup (if equipped) but check for cracks and holes in it. | ||
| - | * A new choke cable bracket and cable/knob assembly for installation on 86-87 Sportsters (available in the c182-1387 accessory kit). \\ Be sure to install the choke cable with the choke in the open or normal running position. \\ When your sure of operaton, cut the excess wire off the end of the cable. | ||
| - | * You may need a set of spacers to install the stock air cleaner on 86-87 models. They are included in the accessory kit. \\ Air cleaner screws should be tightened in sequence, alternating each screw until completely tightened. | ||
| - | * If using the chrome plated 40mm carb (014052) on 1340cc engines; \\ Yyou may need a jet discharge tube (c66-184-2) added to eliminate a lean condition even with the main jet in the full open position. | ||
| - | |||
| - | **Initial carb settings**: \\ | ||
| - | - Open the idle adjustment (low speed) needle 1 full turn open (or out) from fully closed. \\ This needle is on top of the carb closest to engine. \\ Now adjust the main jet (high speed adjustment) out app. 4 turns open (or out). \\ The lowest (or closed) position occurs when the tension spring is coil bound (but not tight). | ||
| - | - Start the engine and check for leaks. \\ Adjust the idle mixture screw until you obtain the highest and smoothest possible idle. \\ Adjust the overall idle speed with the idle stop screw on the throttle lever. | ||
| - | - With the idle speed and mixture adjusted, high speed mixture can be adjusted by running the engine up thru first or second gear to 4500 RPM or above. \\ Overly rich mixture responds by breaking up or running roughly at high RPM. \\ To lean out the main jet, turn the main jet adjustment needle in app. 1/2 turn at a time until the engine responds by pulling cleanly through high RPM ranges in 1st or 2nd gear. | ||
| - | * However, the only way (short of a dyno) to tell is to run the bike to redline in top gear. You can't tune a main jet while the bike is on the side stand. ((Ferrous Head of the XLFORUM http://xlforum.net/forums/showthread.php?t=2071986)) | ||
| - | - After the high speed mix is adjusted, it may be necessary to slightly re-adjust the idle mixture screw. | ||
| - | - Changes in cams, exhaust or engine displacement may require idle or main jet re-adjustments. \\ But the range of adjustments should be enough to accommodate a wide variety of engine sizes and modification levels. | ||
| - | - Extreme caution should be used when handling fuel or making adjustments. \\ Do not make adjustments on a moving motorcycle. | ||
| - | |||
| - | |||
| - | {{:techtalk:ih:carb:bendix_carb_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?t=1434945)) {{:techtalk:ih:carb:bendix_carb_-labeled-_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?p=3891740)) \\ | ||
| - | |||
| - | |||
| - | Here is the adjustable needle. It has a spring (at the top end) to keep tension on the needle. \\ | ||
| - | The pic to the right is of the bottom end of the adjustable main jet needle (installed). Notice how close it comes to the absolute bottom of the float chamber. \\ | ||
| - | Also notice that this particular bowl has no drain plug like the one shown in the factory manual. \\ | ||
| - | |||
| - | {{:techtalk:ih:carb:bendix_pic_4_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showpost.php?p=3171560&postcount=16)) {{:techtalk:ih:carb:bendix_pic_5_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showpost.php?p=3171560&postcount=16)) {{:techtalk:ih:carb:bendix_pic_8_by_piniongear.jpg?direct&270|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?threadid=941501&page=3)) \\ | ||
| - | |||
| - | |||
| - | ====== Troubleshooting ====== | ||
| - | |||
| - | ==== Flooding ==== | ||
| - | |||
| - | Excess fuel should be coming out of the hole in the pic below and the cause is either a too high float level or a stuck / blocked float needle failing to seat. \\ | ||
| - | * Check the float level setting and adjust to 3/16 inch if needed. \\ If it pukes fuel after you set the float correctly, then just buy a new float needle and it will come with a new seat. \\ Replace both of these and you should have no more fuel puking. | ||
| - | * When you install the float bowl back on you will have to take the end of the float spring and wrap it upwards as you install the bowl. \\ This end of the spring has to be inside the bowl and resting against the wall of the bowl. | ||
| - | * No need to put the carb back on the engine yet. \\ Just hook up the gas line from the tank and holding the carb level turn on the petcock. \\ If the needle is seating, no excess fuel should come out the overflow. \\ If it does, tap the side of the bowl with a wrench to dis-lodge the needle. \\ If that does not stop the flow, then you need to buy the kit and replace the needle and seat which come as a matched set. | ||
| - | * Some of the rebuild kits have the wrong size needle, it is too big. Compare it to the old one to see if they are different. ((joestuff of the XLFORUM http://xlforum.net/forums/showthread.php?t=261311)) | ||
| - | * Also check the needle seat for dried varnish or debris, out of round or damaged, | ||
| - | * Make sure the float is moving free and easy, with no sticking. It should take no force whatsoever to move the float up and down. | ||
| - | * Also, check to see if your float, floats. Submerge it in a container of water to check for leaks. | ||
| - | |||
| - | Here is where the overflow hole is located at (left pic, pencil points out the hole). Carefully take the carb apart. \\ | ||
| - | Watch out not to tear the gasket, or else you will need the kit (the gasket is normally very durable). \\ | ||
| - | The only gasket you will find is the one on the float bowl. The right pic below shows what the gasket looks like with the float removed. \\ | ||
| - | |||
| - | {{:techtalk:ih:carb:bendix_pic_1_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?postid=4188583)) {{:techtalk:ih:carb:bendix_pic_2_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?postid=4188583)) {{:techtalk:ih:carb:bench_testing_bendix_float_by_dirtyharry68.jpg?direct&250|}} ((photo by DirtyHarry68 of the XLFORUM http://xlforum.net/forums/showthread.php?t=2072203&page=6)) \\ | ||
| - | |||
| - | ==== Running Rich ==== | ||
| - | |||
| - | Running super rich and fouling the plugs even at highway speed. \\ | ||
| - | The bike would start up easy and after about 20 miles down the road, the plugs would foul. \\ | ||
| - | Pulled the plugs and both were sooty black. \\ | ||
| - | One plug would remain firing but the other cylinder was dead. \\ | ||
| - | The problem was inside the carb. \\ | ||
| - | There is an O-ring around the main jet body that had degraded and broken in half. \\ | ||
| - | This allowed raw fuel to leak directly into the inlet manifold rather than be routed through the main jet. \\ | ||
| - | With a 10 pack of #5 O-rings ($1.29) from the hardware store plumbing department, the carb was fixed. \\ | ||
| - | |||
| - | Sometimes when you push the main jet into the body attaching the bowl, the O-ring rubs on the threads of the body and can "clip" a piece out of the O-ring. ((shovithead of the XLFORUM http://xlforum.net/forums/showthread.php?t=941501&page=6)) \\ | ||
| - | You can use dielectric grease to lubricate them, and they slide right in. \\ | ||
| - | If it clips the O-ring, the main jet will allow the fuel to bleed into the throat causing flooding, hard to make idle, and almost impossible to increase the rpms. \\ | ||
| - | |||
| - | On the needle valve clip, if you run them towards the air cleaner, they seem to work better and not hang up, but i always clip mine a shade shorter, so they won't spin and get tangled up in the float. | ||
| - | |||
| - | {{:techtalk:ih:carb:bendix_parts_1_by_brianbbs67.jpg?direct&300|}} ((photo by brianbbs67 of the XLFORUM http://xlforum.net/forums/showthread.php?s=7b8ab13b7c115b6569746f1c73e14531&p=4829528)) {{:techtalk:ih:carb:bendix_parts_2_by_brianbbs67.jpg?direct&300|}} ((photo by brianbbs67 of the XLFORUM http://xlforum.net/forums/showthread.php?s=7b8ab13b7c115b6569746f1c73e14531&p=4829528)) | ||
| - | {{:techtalk:ih:carb:bad_bendix_main_jet_oring_by_piniongear.jpg?direct&250|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?t=937320)) \\ | ||
| - | |||
| - | ==== High throttle on startup ==== | ||
| - | |||
| - | Look at the throttle butterfly when you begin to start it. \\ | ||
| - | The butterfly should be tight against the idle screw when the throttle is rolled off. There is no way the revs can be high if the throttle is closed. \\ | ||
| - | There is nothing in the carb or anything that you could do (or fail to do) with reassembly other than install the throttle butterfly upside down. \ | ||
| - | The throttle butterfly plate should close off the venturi when you roll the throttle off. \\ Take a look inside the open end (A/C end of the carb) to check this. \\ | ||
| - | Most of the time high throttle on start up is the result of the throttle cable holding open the butterfly. \\ | ||
| - | The main needle adjustment will have no effect on this either. It only comes into play at 1/2 throttle and above. | ||
| - | |||
| - | The red arrow indicates the point where the throttle closes against the idle screw. \\ | ||
| - | With the lever in this position you can look into the carb and the butterfly should be firmly closed. \\ | ||
| - | {{:techtalk:ih:carb:bendix_pic_6_by_piniongear.jpg?direct&300|}} ((photo by piniongear of the XLFORUM http://xlforum.net/forums/showthread.php?t=1068009&page=3)) \\ | ||
| - | |||
| - | ====== Bendix / Zenith Manuals and Other Helpful Links ====== | ||
| - | |||
| - | * [[http://www.zenithfuelsystems.com/|Zenith Fuel Systems.com]] | ||
| - | * [[http://www.zenithfuelsystems.com/documents/HARLEYDAVIDSONCARBURETORS2009.pdf|2009 Zenith Fuel Systems LLC PDF for Harley Carbs]] | ||
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| - | \\ | ||
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| - | |||
| - | [[:techtalk:menu|{{:techtalk:gototechnicalmenu.jpg|}}]] | ||
