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| techtalk:ih:carb01r [2020/08/03 23:24] – [Poor Idle] hippysmack | techtalk:ih:carb01r [2025/02/10 17:08] (current) – [Andrews High Flow Accelerator Pump (Keihin butterfly)] hippysmack | ||
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| * [[techtalk: | * [[techtalk: | ||
| * [[techtalk: | * [[techtalk: | ||
| + | * [[techtalk: | ||
| + | \\ | ||
| For Late 1976-1987 Sportsters. \\ | For Late 1976-1987 Sportsters. \\ | ||
| Line 14: | Line 16: | ||
| - A good rebuild kit (new rubbers all through a carb make a big difference to it's performance) | - A good rebuild kit (new rubbers all through a carb make a big difference to it's performance) | ||
| - | The L76-78 Keihin butterfly carbs worked the best and had more adjustment to them. ((oldnavy of the XLFORUM | + | The L76-78 Keihin butterfly carbs worked the best and had more adjustment to them. ((oldnavy of the XLFORUM |
| They had no choke cam, a deeper frost plug in the top and a wider range in them. \\ | They had no choke cam, a deeper frost plug in the top and a wider range in them. \\ | ||
| Another factory fix was to seal the frost plug in the top with silicone to be sure they weren' | Another factory fix was to seal the frost plug in the top with silicone to be sure they weren' | ||
| To find out which later carb you have; \\ | To find out which later carb you have; \\ | ||
| - | On 79 or later Keihin butterfly carbs, measure the venturi. 34mm = Sportster, 38mm = big twin. ((IronMick of the XLFORUM | + | On 79 or later Keihin butterfly carbs, measure the venturi. 34mm = Sportster, 38mm = big twin. ((IronMick of the XLFORUM |
| You can cut two pieces of cereal/ | You can cut two pieces of cereal/ | ||
| See which best fits the most narrow part (throat) of the venturi. \\ | See which best fits the most narrow part (throat) of the venturi. \\ | ||
| - | {{: | + | {{: |
| ====== Choke ====== | ====== Choke ====== | ||
| - | |||
| On L76-78 Keihin carbs, the choke system is standalone with a choke plate and an actuating rod. \\ | On L76-78 Keihin carbs, the choke system is standalone with a choke plate and an actuating rod. \\ | ||
| On 79-up carbs, the choke system is composed of a choke, actuating rod and a fast idle cam. \\ | On 79-up carbs, the choke system is composed of a choke, actuating rod and a fast idle cam. \\ | ||
| Line 38: | Line 38: | ||
| - Fully open (off for normal operating temp). | - Fully open (off for normal operating temp). | ||
| **79-87 models**: \\ | **79-87 models**: \\ | ||
| - | The choke has 4 basic positions ((IronMick of the XLFORUM | + | The choke has 4 basic positions ((IronMick of the XLFORUM |
| - Full choke for cold startup (knob all the way in). | - Full choke for cold startup (knob all the way in). | ||
| - Choke out a little (maybe 1/2"). \\ (choke plate is still fully open but the fast idle cam moves the throttle valve to the fast idle position) | - Choke out a little (maybe 1/2"). \\ (choke plate is still fully open but the fast idle cam moves the throttle valve to the fast idle position) | ||
| Line 44: | Line 44: | ||
| - Choke all the way out, plate is fully closed and valve is in the highest idle position | - Choke all the way out, plate is fully closed and valve is in the highest idle position | ||
| - | Check your butterfly shaft also. If its loose, the bushings are worn and you'll be sucking air. ((egarrett of the XLFORUM | + | Check your butterfly shaft also. If its loose, the bushings are worn and you'll be sucking air. ((egarrett of the XLFORUM |
| ====== Low Speed System (idle circuit) ====== | ====== Low Speed System (idle circuit) ====== | ||
| - | |||
| The low speed system affects idle up thru about half throttle (idle, low and intermediate speeds when the throttle valve is closed or only partially open). ((1970-1978 HD Sportster FSM pg 3-60)) \\ | The low speed system affects idle up thru about half throttle (idle, low and intermediate speeds when the throttle valve is closed or only partially open). ((1970-1978 HD Sportster FSM pg 3-60)) \\ | ||
| **76 only**; At idle, fuel enters the slow jet where it is metered. \\ | **76 only**; At idle, fuel enters the slow jet where it is metered. \\ | ||
| Line 63: | Line 62: | ||
| - Adjust idle SPEED screw again to get desired idle speed. | - Adjust idle SPEED screw again to get desired idle speed. | ||
| - | **Observations from Hopper of the XLFORUM**: ((http:// | + | **Observations from Hopper of the XLFORUM**: ((https://www.xlforum.net/ |
| < | < | ||
| Line 80: | Line 79: | ||
| **Further explanation from IronMick of the XLFORUM**; \\ | **Further explanation from IronMick of the XLFORUM**; \\ | ||
| - | < | + | < |
| If this is the case remove the carb from the bike and clean it up. Some guys try to do carb work with the carb in the bike. This is generally a very bad idea. \\ | If this is the case remove the carb from the bike and clean it up. Some guys try to do carb work with the carb in the bike. This is generally a very bad idea. \\ | ||
| Line 87: | Line 86: | ||
| The screw usually comes out easily. The other parts may require some work. \\ | The screw usually comes out easily. The other parts may require some work. \\ | ||
| The best technique is to stick a pipe cleaner in the hole, twist it around, and, like magic, out come the other parts on the end of the pipe cleaner. \\ | The best technique is to stick a pipe cleaner in the hole, twist it around, and, like magic, out come the other parts on the end of the pipe cleaner. \\ | ||
| - | * The pilot screw adjustment mainly affects the idle speed operation of the engine. ((IronMick of the XLFORUM | + | * The pilot screw adjustment mainly affects the idle speed operation of the engine. ((IronMick of the XLFORUM |
| The mixture screw does not have a large range of adjustment, if you're running lean, you may need to increase the low speed jet size. \\ (after you have eliminated all other contributing factors) \\ | The mixture screw does not have a large range of adjustment, if you're running lean, you may need to increase the low speed jet size. \\ (after you have eliminated all other contributing factors) \\ | ||
| **Note**: 1966 to 1978 Sportster carbs do not have the O-ring and washer in the pilot screw passage. | **Note**: 1966 to 1978 Sportster carbs do not have the O-ring and washer in the pilot screw passage. | ||
| Line 104: | Line 103: | ||
| </ | </ | ||
| - | |||
| ===== Air/Fuel Mixture Adjustment ===== | ===== Air/Fuel Mixture Adjustment ===== | ||
| - | |||
| **Low speed / idle mixture screw**: \\ | **Low speed / idle mixture screw**: \\ | ||
| - | Other names include the idle mixture screw or the pilot screw. ((IronMick of the XLFORUM | + | Other names include the idle mixture screw or the pilot screw. ((IronMick of the XLFORUM |
| - | You may get smoother running by adjusting this screw as it adjusts the flow of gasoline at idle. ((Hopper of the XLFORUM | + | You may get smoother running by adjusting this screw as it adjusts the flow of gasoline at idle. ((Hopper of the XLFORUM |
| The idle mixture screw is held in place by a spring on top of the carburetor near the intake mounting flange on all models. \\ | The idle mixture screw is held in place by a spring on top of the carburetor near the intake mounting flange on all models. \\ | ||
| Line 120: | Line 117: | ||
| * Turning the screw in (clockwise) leans the mixture. | * Turning the screw in (clockwise) leans the mixture. | ||
| * Turning the screw out (counter-clockwise) richens the mixture. | * Turning the screw out (counter-clockwise) richens the mixture. | ||
| - | The pilot screw tuning is dependent on your slow speed jet size. ((83XLX of the XLFORUM | + | The pilot screw tuning is dependent on your slow speed jet size. ((83XLX of the XLFORUM |
| Needing it too far in or out for proper mixture will indicate the need for a smaller or larger low speed jet. | Needing it too far in or out for proper mixture will indicate the need for a smaller or larger low speed jet. | ||
| - | |Idle Mixture Screw: L76-78 ((photo by Hopper of the XLFORUM | + | |Idle Mixture Screw: L76-78 ((photo by Hopper of the XLFORUM |
| |{{: | |{{: | ||
| ===== Idle Speed Adjustment ===== | ===== Idle Speed Adjustment ===== | ||
| - | The idle speed adjuster is just a butterfly stop screw and it adjusts the movement on the return of the throttle cable. ((Hopper of the XLFORUM | + | The idle speed adjuster is just a butterfly stop screw and it adjusts the movement on the return of the throttle cable. ((Hopper of the XLFORUM |
| Adjust the throttle stop screw to make the engine idle at the desired speed with the throttle closed. ((1970-1978 HD Sportster FSM pg 3-61)) \\ | Adjust the throttle stop screw to make the engine idle at the desired speed with the throttle closed. ((1970-1978 HD Sportster FSM pg 3-61)) \\ | ||
| **Notes**: \\ | **Notes**: \\ | ||
| Line 149: | Line 146: | ||
| * Turn the fast idle adjusting screw in or out to set the fast idle at 1500 RPM. | * Turn the fast idle adjusting screw in or out to set the fast idle at 1500 RPM. | ||
| - | |Throttle Stop Screw (idle speed adjuster): ((photo by Hopper of the XLFORUM | + | |Throttle Stop Screw (idle speed adjuster): ((photo by Hopper of the XLFORUM |
| |{{: | |{{: | ||
| ==== Choke Shaft and Plastic Parts (76-E78) ==== | ==== Choke Shaft and Plastic Parts (76-E78) ==== | ||
| - | |||
| Kits were available from the MoCo for 76-78 FX & FL carbs to adapt for a fast idle cam. It was also available as a replacement for 79-up carbs. \\ | Kits were available from the MoCo for 76-78 FX & FL carbs to adapt for a fast idle cam. It was also available as a replacement for 79-up carbs. \\ | ||
| The Choke Shaft Kit is (27045-78) and the Plastic Parts kit (27046-78) as shown below (with the parts list including 3 springs, 2 clips and 2 washers). \\ | The Choke Shaft Kit is (27045-78) and the Plastic Parts kit (27046-78) as shown below (with the parts list including 3 springs, 2 clips and 2 washers). \\ | ||
| {{: | {{: | ||
| The ball under the choke lever drive must ride in the detents on the bottom of the choke lever drive. \\ | The ball under the choke lever drive must ride in the detents on the bottom of the choke lever drive. \\ | ||
| - | ==== Fast Idle Cam (79-up) ==== | ||
| + | ==== Fast Idle Cam (79-up) ==== | ||
| The fast idle cam operates in conjunction with the choke to progressively raise the idle speed as the choke disc closes. ((1979-1985 Hd FSM pg 4-3)) \\ | The fast idle cam operates in conjunction with the choke to progressively raise the idle speed as the choke disc closes. ((1979-1985 Hd FSM pg 4-3)) \\ | ||
| Engine speed is increased as the choke knob is pulled out. \\ | Engine speed is increased as the choke knob is pulled out. \\ | ||
| By moving the choke knob, the choke and fast idle can be adjusted for a cold or warm engine. \\ | By moving the choke knob, the choke and fast idle can be adjusted for a cold or warm engine. \\ | ||
| This should be set to 1500 RPM with the bike fully warmed up. \\ | This should be set to 1500 RPM with the bike fully warmed up. \\ | ||
| - | When the choke lever is pulled out 1/4" to 1/2", it is in the fast idle position. ((IronMick of the XLFORUM | + | When the choke lever is pulled out 1/4" to 1/2", it is in the fast idle position. ((IronMick of the XLFORUM |
| After starting with full choke you push it in to this setting until it is warmed up [a few minutes] then push it in the rest of the way. \\ | After starting with full choke you push it in to this setting until it is warmed up [a few minutes] then push it in the rest of the way. \\ | ||
| - | {{: | + | {{: |
| ===== Slow Jet ===== | ===== Slow Jet ===== | ||
| Other notable names include the pilot jet or idle jet. \\ | Other notable names include the pilot jet or idle jet. \\ | ||
| + | |||
| ==== Rubber bung ==== | ==== Rubber bung ==== | ||
| - | |||
| **L76 Sportster carbs**; \\ | **L76 Sportster carbs**; \\ | ||
| - | The very first 1976 style Keihin carbs do not use the rubber plug beneath the slow jet. ((Hopper of the XLFORUM | + | The very first 1976 style Keihin carbs do not use the rubber plug beneath the slow jet. ((Hopper of the XLFORUM |
| **77-up carbs**; \\ | **77-up carbs**; \\ | ||
| - | The slow jet is under the rubber bung in the pic above. You take out the rubber bung, then unscrew the small brass jet with a screw driver that is a tight fit. ((Hopper of the XLFORUM | + | The slow jet is under the rubber bung in the pic above. You take out the rubber bung, then unscrew the small brass jet with a screw driver that is a tight fit. ((Hopper of the XLFORUM |
| The rubber bung is essential. The bike will run really rough if it comes loose or falls out. \\ | The rubber bung is essential. The bike will run really rough if it comes loose or falls out. \\ | ||
| - | Looking at the carb upside down the passage will be drilled below the main jet and above the pilot jet. ((ryder rick of the XLFORUM | + | Looking at the carb upside down the passage will be drilled below the main jet and above the pilot jet. ((ryder rick of the XLFORUM |
| With the plug installed, the pilot jet draws fuel from and through the main jet. \\ | With the plug installed, the pilot jet draws fuel from and through the main jet. \\ | ||
| You must run with the plug in place or the main jet will be bypassed by the drilled passage and it will run very rich. \\ | You must run with the plug in place or the main jet will be bypassed by the drilled passage and it will run very rich. \\ | ||
| **Correction of Lean Mixture Problems Due to the Rubber Bung** \\ | **Correction of Lean Mixture Problems Due to the Rubber Bung** \\ | ||
| - | Sometimes, the black plug in the low speed jet is too long and should be trimmed off to allow more fuel in the low speed side. ((oldnavy of the XLFORUM | + | Sometimes, the black plug in the low speed jet is too long and should be trimmed off to allow more fuel in the low speed side. ((oldnavy of the XLFORUM |
| Trim off as much as needed to still hold it in without falling out. Per TSB #707, correct by either modifying or replacing the plug. ((HD TSB #M707 dated December 1, 1976)) \\ | Trim off as much as needed to still hold it in without falling out. Per TSB #707, correct by either modifying or replacing the plug. ((HD TSB #M707 dated December 1, 1976)) \\ | ||
| Either cut a plug so it is 5mm (.20") from shoulder to tip or replace it with a new plug (27385-76). Refer to bulletin 694 for disassembly and assembly procedure to remove and replace plug. \\ | Either cut a plug so it is 5mm (.20") from shoulder to tip or replace it with a new plug (27385-76). Refer to bulletin 694 for disassembly and assembly procedure to remove and replace plug. \\ | ||
| Line 192: | Line 187: | ||
| Interestingly, | Interestingly, | ||
| It is not clear why the L76 Sportster carb was different. \\ | It is not clear why the L76 Sportster carb was different. \\ | ||
| - | {{: | + | {{: |
| ==== Slow jet ==== | ==== Slow jet ==== | ||
| - | |||
| You might have to grind the sides off a screwdriver to get it to go up inside the hole to the jet. \\ | You might have to grind the sides off a screwdriver to get it to go up inside the hole to the jet. \\ | ||
| If you have anything other than factory original exhaust and air filter, you will most likely need to go up one or two sizes in slow speed jet. \\ | If you have anything other than factory original exhaust and air filter, you will most likely need to go up one or two sizes in slow speed jet. \\ | ||
| If your idle mixture screw works best more than 1-1/4 turns open, you need a bigger low speed jet. \\ | If your idle mixture screw works best more than 1-1/4 turns open, you need a bigger low speed jet. \\ | ||
| If your bike spits back through the carb at all, you need a bigger low speed jet. \\ | If your bike spits back through the carb at all, you need a bigger low speed jet. \\ | ||
| - | If your slow jet is too small, the engine misfires on acceleration. ((IronMick of the XLFORUM | + | If your slow jet is too small, the engine misfires on acceleration. ((IronMick of the XLFORUM |
| Click here for [[techtalk: | Click here for [[techtalk: | ||
| Fitting an 80 model carb, for instance, will make it run much better. Later 79-onwards and those with 34mm carbs have smaller jets. \\ | Fitting an 80 model carb, for instance, will make it run much better. Later 79-onwards and those with 34mm carbs have smaller jets. \\ | ||
| Line 211: | Line 205: | ||
| You drill the jet very carefully, one size at a time by hand, twirling the jet down over the drill gradually. \\ | You drill the jet very carefully, one size at a time by hand, twirling the jet down over the drill gradually. \\ | ||
| Do not use an electric drill, it will make a big hole and possibly break the drill bit. \\ | Do not use an electric drill, it will make a big hole and possibly break the drill bit. \\ | ||
| - | Buy 2 small jets, and a good drill index (number, letter, fractional or the metric equivalent). ((forqueue of the XLFORUM | + | Buy 2 small jets, and a good drill index (number, letter, fractional or the metric equivalent). ((forqueue of the XLFORUM |
| Drill out the small jet one size at a time until you become too rich. Drill out the remaining jet 1 size down. \\ | Drill out the small jet one size at a time until you become too rich. Drill out the remaining jet 1 size down. \\ | ||
| The right size slow speed jet is the most important factor in getting a good idle, starting, running up to half throttle and stopping carb farts. \\ | The right size slow speed jet is the most important factor in getting a good idle, starting, running up to half throttle and stopping carb farts. \\ | ||
| This is a slow jet and jet hand-drill (or pin vise). \\ | This is a slow jet and jet hand-drill (or pin vise). \\ | ||
| - | {{: | + | {{: |
| ====== Mid-range Circuit / Idle Transfer Ports ====== | ====== Mid-range Circuit / Idle Transfer Ports ====== | ||
| - | |||
| As the throttle valve opens, the air / fuel mixture from the slow jet is drawn into the venture through the idle transfer ports. \\ | As the throttle valve opens, the air / fuel mixture from the slow jet is drawn into the venture through the idle transfer ports. \\ | ||
| When the throttle valve uncovers the midrange port, raw fuel from the float chamber is also drawn into the engine. \\ | When the throttle valve uncovers the midrange port, raw fuel from the float chamber is also drawn into the engine. \\ | ||
| - | Another thing that affects low speed running, mostly as you crack the throttle open from idle, is the bypass ports. ((Hopper of the XLFORUM | + | Another thing that affects low speed running, mostly as you crack the throttle open from idle, is the bypass ports. ((Hopper of the XLFORUM |
| This is a row of four tiny holes in the top of the carb, just in front of the idle mixture hole, directly below the idle mixture screw. \\ | This is a row of four tiny holes in the top of the carb, just in front of the idle mixture hole, directly below the idle mixture screw. \\ | ||
| Line 228: | Line 221: | ||
| So as the throttle opens from idle, more gas is allowed in to match the extra air flowing in. \\ | So as the throttle opens from idle, more gas is allowed in to match the extra air flowing in. \\ | ||
| - | The ports in the carb venturi are made active as follows as you open the throttle: ((IronMick of the XLFORUM | + | The ports in the carb venturi are made active as follows as you open the throttle: ((IronMick of the XLFORUM |
| - Idle port, controlled by pilot screw | - Idle port, controlled by pilot screw | ||
| - 1st of 4 idle transfer ports are active at idle. | - 1st of 4 idle transfer ports are active at idle. | ||
| Line 246: | Line 239: | ||
| Apply a minimal amount only to the joints between the edges of the plugs and the casting. \\ | Apply a minimal amount only to the joints between the edges of the plugs and the casting. \\ | ||
| - | |Idle transfer ports inside. ((photo by Hopper of the XLFORUM | + | |Idle transfer ports inside. ((photo by Hopper of the XLFORUM |
| |{{: | |{{: | ||
| Line 253: | Line 246: | ||
| Fuel is metered by the main jet and enters the main jet bleed tube where it mixes with air entering through the main jet air passage. \\ | Fuel is metered by the main jet and enters the main jet bleed tube where it mixes with air entering through the main jet air passage. \\ | ||
| This air/fuel mixture then enters the venture from the main nozzle. \\ | This air/fuel mixture then enters the venture from the main nozzle. \\ | ||
| + | |||
| ===== Main Jet ===== | ===== Main Jet ===== | ||
| The main jet has no adjustment. Fuel is metered by the main jet during high speed operation. \\ | The main jet has no adjustment. Fuel is metered by the main jet during high speed operation. \\ | ||
| Line 262: | Line 256: | ||
| All year Keihin jet locations: \\ | All year Keihin jet locations: \\ | ||
| - | {{: | + | {{: |
| ===== Installing an Adjustable Main Jet (L76-87) ===== | ===== Installing an Adjustable Main Jet (L76-87) ===== | ||
| There is an adjustable main jet available from J&P Cycles or others. \\ | There is an adjustable main jet available from J&P Cycles or others. \\ | ||
| These work great and you don't have to fool around jet guessing whether you have the right size main jet or not. \\ | These work great and you don't have to fool around jet guessing whether you have the right size main jet or not. \\ | ||
| - | They are simple to adjust. Just wind it up to about 65 MPH and run it in until it misses and back it out about a full turn. ((oldnavy of the XLFORUM | + | They are simple to adjust. Just wind it up to about 65 MPH and run it in until it misses and back it out about a full turn. ((oldnavy of the XLFORUM |
| This kit can be purchased online. It comes with an installation guide and index pointer. \\ | This kit can be purchased online. It comes with an installation guide and index pointer. \\ | ||
| Line 281: | Line 275: | ||
| The bowl is once again removed and a 1/ | The bowl is once again removed and a 1/ | ||
| After checking for burrs, removing the index tool and guide and cleaning up, the adjustable jet is installed in the float bowl. \\ | After checking for burrs, removing the index tool and guide and cleaning up, the adjustable jet is installed in the float bowl. \\ | ||
| - | (partially unscrew the small 'T' | + | (partially unscrew the small "T" |
| Remove the nut from the adjustable jet, insert the jet through the 15/64" hole drilled earlier. \\ | Remove the nut from the adjustable jet, insert the jet through the 15/64" hole drilled earlier. \\ | ||
| - | Then re-tighten the bowl and gently screw in the 'T' | + | Then re-tighten the bowl and gently screw in the "T" |
| Finer tuning can be achieved by reading the spark plugs and small adjustments to the “T” handle. \\ | Finer tuning can be achieved by reading the spark plugs and small adjustments to the “T” handle. \\ | ||
| This adjustable jet eliminates the chore of carrying and continually changing different main jets with every change in exhaust system or air cleaner. \\ | This adjustable jet eliminates the chore of carrying and continually changing different main jets with every change in exhaust system or air cleaner. \\ | ||
| - | The hole in the bowl for the 'T' | + | The hole in the bowl for the "T" |
| The adjustable main jet is designed to operate in conjunction with a 1.80 main jet included with the kit. \\ | The adjustable main jet is designed to operate in conjunction with a 1.80 main jet included with the kit. \\ | ||
| - | Make sure you record or remember the number of turns off the seat and back off the 'T' | + | Make sure you record or remember the number of turns off the seat and back off the "T" |
| This will help prevent needle / jet interference when the float bowl is reinstalled. \\ | This will help prevent needle / jet interference when the float bowl is reinstalled. \\ | ||
| For initial adjustment (standard pipes and A/C) it's recommended that the adjustment needle be backed out four (4) turns from the seat. | For initial adjustment (standard pipes and A/C) it's recommended that the adjustment needle be backed out four (4) turns from the seat. | ||
| Line 295: | Line 289: | ||
| |{{: | |{{: | ||
| - | |||
| ====== | ====== | ||
| Line 330: | Line 323: | ||
| \\ | \\ | ||
| ===== Accel Pump Check Valves ===== | ===== Accel Pump Check Valves ===== | ||
| - | Keihin carbs have 2 check valves in the accel pump circuit. ((Dr Dick of the XLFORUM | + | Keihin carbs have 2 check valves in the accel pump circuit. ((Dr Dick of the XLFORUM |
| - The inlet check ball. \\ It's captive in the pump cover pn (27364-76}. You can hear it when you shake the cover. | - The inlet check ball. \\ It's captive in the pump cover pn (27364-76}. You can hear it when you shake the cover. | ||
| - The outlet weighted needle (this is the one that resembles a float inlet valve). \\ This valve is captive in the bowl casting (inside the spray nozzle). You can hear it when you shake the bowl. | - The outlet weighted needle (this is the one that resembles a float inlet valve). \\ This valve is captive in the bowl casting (inside the spray nozzle). You can hear it when you shake the bowl. | ||
| Line 343: | Line 336: | ||
| You can see a little hole in the passage from the pump to the nozzle. It's on -76 and -76A bowls only. The -77 don't have that hole. | You can see a little hole in the passage from the pump to the nozzle. It's on -76 and -76A bowls only. The -77 don't have that hole. | ||
| Additionally, | Additionally, | ||
| - | {{: | + | {{: |
| ===== Accel Pump Jet ===== | ===== Accel Pump Jet ===== | ||
| - | |||
| How fast the pump's gas is delivered to the carb depends on the strength of the spring pushing on the pump rod and the size of the pump jet. \\ | How fast the pump's gas is delivered to the carb depends on the strength of the spring pushing on the pump rod and the size of the pump jet. \\ | ||
| You can control the rod throw, and therefore the volume with the limit screw (or the one you've added on later carbs). \\ | You can control the rod throw, and therefore the volume with the limit screw (or the one you've added on later carbs). \\ | ||
| Line 358: | Line 350: | ||
| And you can't get the earlier -77 anymore (outside of occasional NOS or Ebay items). But you can solder up the 80 and re-drill to a smaller size. \\ | And you can't get the earlier -77 anymore (outside of occasional NOS or Ebay items). But you can solder up the 80 and re-drill to a smaller size. \\ | ||
| A #76 drill bit will give you an app size 50 jet. You may have to clean the solder out of the large hole but that's easily done. \\ | A #76 drill bit will give you an app size 50 jet. You may have to clean the solder out of the large hole but that's easily done. \\ | ||
| - | |Accelerator pump jet location: ((photo by Hopper of the XLFORUM | + | |Accelerator pump jet location: ((photo by Hopper of the XLFORUM |
| |{{: | |{{: | ||
| Line 380: | Line 372: | ||
| The accelerator pump adjusting screw is missing in the second pic below. Once removed, it gives full pump stroke all the time. \\ | The accelerator pump adjusting screw is missing in the second pic below. Once removed, it gives full pump stroke all the time. \\ | ||
| - | |Early accelerator pump adjusting screw. ((photo by Hopper of the XLFORUM | + | |Early accelerator pump adjusting screw. ((photo by Hopper of the XLFORUM |
| |{{: | |{{: | ||
| - | |||
| ===== Check the pump nozzle aim ===== | ===== Check the pump nozzle aim ===== | ||
| Line 389: | Line 380: | ||
| 77-78 float bowl (27395-77) with short accel pump nozzle. \\ | 77-78 float bowl (27395-77) with short accel pump nozzle. \\ | ||
| 79-85 float bowl (27890-78) with tall accel pump nozzle. \\ | 79-85 float bowl (27890-78) with tall accel pump nozzle. \\ | ||
| + | |||
| ==== 79 and later 34mm Keihin butterfly carbs ==== | ==== 79 and later 34mm Keihin butterfly carbs ==== | ||
| - | + | Do not re-aim the 79-up accelerator pump as recommended in Joe Minton' | |
| - | Do not re-aim the 79-up accelerator pump as recommended in Joe Minton' | + | |
| The accel pump jet in 79-up carbs is taller and right up to the height of the choke plate. \\ | The accel pump jet in 79-up carbs is taller and right up to the height of the choke plate. \\ | ||
| So there is no need for the extra notch in the plate and or to adjust the aim of the nozzle. \\ | So there is no need for the extra notch in the plate and or to adjust the aim of the nozzle. \\ | ||
| Line 401: | Line 392: | ||
| As long as the jet is aimed directly at the rear cylinder roughly equal amounts of fuel will be directed to each cylinder by the force of the air stream. \\ | As long as the jet is aimed directly at the rear cylinder roughly equal amounts of fuel will be directed to each cylinder by the force of the air stream. \\ | ||
| So, if you are running a Keihin butterfly carb, the fuel should go thru the middle of the cutout in the choke plate with the choke fully open. \\ | So, if you are running a Keihin butterfly carb, the fuel should go thru the middle of the cutout in the choke plate with the choke fully open. \\ | ||
| - | {{: | + | {{: |
| ==== 76-78 38mm Keihin' | ==== 76-78 38mm Keihin' | ||
| Line 421: | Line 412: | ||
| **Caution**: | **Caution**: | ||
| It is possible to break the nozzle when trying to remove it. Replacements from J&P etc. may still be available. \\ | It is possible to break the nozzle when trying to remove it. Replacements from J&P etc. may still be available. \\ | ||
| - | As a precaution, you can heat the float bowl gently and evenly. ((Hopper of the XLFORUM | + | As a precaution, you can heat the float bowl gently and evenly. ((Hopper of the XLFORUM |
| The aluminum will expand more than the brass nozzle, so the fit will become loose and make it easier to turn the nozzle. \\ | The aluminum will expand more than the brass nozzle, so the fit will become loose and make it easier to turn the nozzle. \\ | ||
| You can heat it with a heat gun, a good hairdryer or even drop the float bowl in a pot of boiling water for a few minutes to heat it up. \\ | You can heat it with a heat gun, a good hairdryer or even drop the float bowl in a pot of boiling water for a few minutes to heat it up. \\ | ||
| - | |Choke butterfly notch. ((photo by Hopper of the XLFORUM | + | |Choke butterfly notch. ((photo by Hopper of the XLFORUM |
| |{{: | |{{: | ||
| Line 431: | Line 422: | ||
| The pencil shows the direction the jet hole was facing before adjustment. \\ | The pencil shows the direction the jet hole was facing before adjustment. \\ | ||
| - | |Before adjusting (factory position). ((photo by Hopper of the XLFORUM | + | |Before adjusting (factory position). ((photo by Hopper of the XLFORUM |
| |{{: | |{{: | ||
| Line 443: | Line 434: | ||
| Any wiring that that may get too hot / catch fire doesn' | Any wiring that that may get too hot / catch fire doesn' | ||
| - | |After adjusting. ((photo by Hopper of the XLFORUM | + | |After adjusting. ((photo by Hopper of the XLFORUM |
| |{{: | |{{: | ||
| ===== Andrews High Flow Accelerator Pump (Keihin butterfly) ===== | ===== Andrews High Flow Accelerator Pump (Keihin butterfly) ===== | ||
| + | Andrews Products (269050). It was also sold through V-twin as part number (35-9050). \\ | ||
| + | {{: | ||
| - | 79-up 34mm Keihin carbs will not fill there accelerator pumps as quickly as the 76-78 38mm ones. ((Joe Minton Article " | + | 79-up 34mm Keihin carbs will not fill there accelerator pumps as quickly as the 76-78 38mm ones. ((Joe Minton Article " |
| - | The earlier pump would refill in about 1/2 second. The later one takes three seconds. \\ | + | The earlier pump would refill in about 1/2 second. The later one takes three seconds.\\ |
| - | The earlier pump will allow you to get by the choke and will help you catch the engine if you let the clutch out too fast at a red light. \\ | + | The earlier pump will allow you to get by the choke and will help you catch the engine if you let the clutch out too fast at a red light.\\ |
| - | The main difference is the pump housing. The early accel pump passages had both an inlet and an outlet hole for gas routing. \\ | + | The main difference is the pump housing. The early accel pump passages had both an inlet and an outlet hole for gas routing.\\ |
| - | The Andrews pump is reportedly the same as Harley part (27364-76) for the early 38mm Keihins. \\ | + | The Andrews pump is reportedly the same as Harley part (27364-76) for the early 38mm Keihins.\\ |
| - | Actually, if you can find a 38mm pump and drill the hole in your carb body, you'll have the old style accel pump. \\ | + | Actually, if you can find a 38mm pump and drill the hole in your carb body, you'll have the old style accel pump. |
| - | On 1980-1988 Keihin carbs, the stock accelerator pump is restricted by eliminating the check valves in the pump. A high flow accelerator pump puts them back. ((IronMick of the XLFORUM | + | On 1980-1988 Keihin carbs, the stock accelerator pump is restricted by eliminating the check valves in the pump. A high flow accelerator pump puts them back. ((IronMick of the XLFORUM |
| - | The result is increased fuel flow through the pump and greatly improved low end and mid range throttle response. \\ | + | Not intended for 1989 and later CV carburetors. \\ |
| - | The Keihin butterfly carb already has an accelerator pump, so the Andrews high-flow pump body just replaces the stock one on the bottom of the float bowl. ((83XLX of the XLFORUM | + | The Keihin butterfly carb already has an accelerator pump, so the Andrews high-flow pump body just replaces the stock one on the bottom of the float bowl. ((XLX of the XLFORUM |
| - | There is one on the [[https:// | + | |
| - | It has a V-twin part number of 35-9050, Manufacturer Keihin, Part Number: 269050. \\ | + | |
| - | // | + | |
| - | Makes since as Andrews used to make the Flowmaster carb. \\ | + | |
| - | The pump is listed as out of stock and has been since at least of march 2018 yet the listing is still up. \\ | + | |
| - | In fact and according to the V-twin website, it's been discontinued and no replacement is listed. | + | |
| - | Installation instructions | + | The Flowmaster carb accelerator pump kit improves throttle response on Keihin carburetor models with a greater volume of fuel from the pump circuit. Makes since as Andrews |
| + | The pump is listed as out of stock and has been since at least of march 2018 yet the listing is still up.\\ | ||
| + | In fact and according to the V-twin website, it's been discontinued and no replacement is listed. \\ | ||
| - | Features: ((http:// | + | Features: ((http:// |
| * Improves throttle response | * Improves throttle response | ||
| * Larger fuel volume/ | * Larger fuel volume/ | ||
| Line 476: | Line 465: | ||
| * Dimensions: 5" | * Dimensions: 5" | ||
| - | A high flow accelerator pump is also a great all around upgrade for these carbs. ((oldnavy of the XLFORUM | + | A high flow accelerator pump is also a great all around upgrade for these carbs. ((oldnavy of the XLFORUM |
| - | {{: | + | |
| - | **How the High Flow Accelerator Pump should be installed**: | + | **How the High Flow Accelerator Pump should be installed**: |
| - | High Flow Accelerator Pump for Stock Keihin Carburetors For Stock Keihin Carbs from 1980-1988)) | + | |
| - Remove float bowl from carburetor. There are four screws holding it in place. \\ It is not necessary to remove the entire carburetor from the engine to install your new high flow accelerator pump. | - Remove float bowl from carburetor. There are four screws holding it in place. \\ It is not necessary to remove the entire carburetor from the engine to install your new high flow accelerator pump. | ||
| - | - Clean any fuel residue from the bowl assembly and remove the stock accelerator pump housing. \\ It is held in place with three screws but one of them already has been removed with the bowl. | + | - Clean any fuel residue from the bowl assembly and remove the stock accelerator pump housing. \\ It is held in place with three screws but one of them already has been removed with the bowl. |
| - Position the bowl upside down for drilling a single hole through the bottom. | - Position the bowl upside down for drilling a single hole through the bottom. | ||
| - | - Any drill of approximately 1/16 diameter will be quite satisfactory. \\ The exact location for this hole is already marked with a dimple on the bottom of the float bowl casting as shown in photo below. \\ {{: | + | - Any drill of approximately 1/16 diameter will be quite satisfactory. \\ The exact location for this hole is already marked with a dimple on the bottom of the float bowl casting as shown in photo below. \\ {{: |
| - Feed the drill through until it breaks out into the float chamber. \\ Don’t worry if the hole breaks into either a cross drilled passage or through the actual bottom of the bowl. \\ The location is not critical as long as fuel can feed through into the accelerator pump. | - Feed the drill through until it breaks out into the float chamber. \\ Don’t worry if the hole breaks into either a cross drilled passage or through the actual bottom of the bowl. \\ The location is not critical as long as fuel can feed through into the accelerator pump. | ||
| - Thoroughly clean any drill chips from the bowl. There is a small bypass hole in the bottom of the bowl which does not have to be plugged. \\ Several earlier magazine articles have recommended plugging this hole but there will be no measurable benefit from doing so. | - Thoroughly clean any drill chips from the bowl. There is a small bypass hole in the bottom of the bowl which does not have to be plugged. \\ Several earlier magazine articles have recommended plugging this hole but there will be no measurable benefit from doing so. | ||
| Line 490: | Line 477: | ||
| - If the accelerator pump jet needs to aimed differently, | - If the accelerator pump jet needs to aimed differently, | ||
| - Reinstall the bowl and pump assembly back onto the carburetor body to complete the job. \\ The extra fuel from the larger capacity pump should result in smoother, quicker throttle response especially off idle or at low RPM. | - Reinstall the bowl and pump assembly back onto the carburetor body to complete the job. \\ The extra fuel from the larger capacity pump should result in smoother, quicker throttle response especially off idle or at low RPM. | ||
| + | |||
| ===== Alternative using CV accelerator pump ===== | ===== Alternative using CV accelerator pump ===== | ||
| - | + | It looks like Keihin made all these covers so any of the basic raw castings can have additional operations incorporated to be used in any of their many configurations. ((chevelle of the XLFORUM | |
| - | It looks like Keihin made all these covers so any of the basic raw castings can have additional operations incorporated to be used in any of their many configurations. ((chevelle of the XLFORUM | + | |
| The stock pump cover for non CV Harley carbs (2-2) uses the same passage for supply and pump shot. \\ | The stock pump cover for non CV Harley carbs (2-2) uses the same passage for supply and pump shot. \\ | ||
| The high flow cover uses separate passages for supply and pump shot (4-2). \\ | The high flow cover uses separate passages for supply and pump shot (4-2). \\ | ||
| Line 506: | Line 493: | ||
| Note: All orifices in covers are the same. \\ | Note: All orifices in covers are the same. \\ | ||
| - | {{: | + | {{: |
| ====== Float Level Adjustment ====== | ====== Float Level Adjustment ====== | ||
| Line 526: | Line 513: | ||
| ==== 76-78 Sportster carbs ==== | ==== 76-78 Sportster carbs ==== | ||
| - | |||
| Two positions of the float valve must be set; The valve fully closed and The valve fully open. \\ | Two positions of the float valve must be set; The valve fully closed and The valve fully open. \\ | ||
| Setting the closed position lower will tend to make the carb act lean at low speed. \\ | Setting the closed position lower will tend to make the carb act lean at low speed. \\ | ||
| Line 540: | Line 526: | ||
| The actual adjustments are made by carefully bending the two tabs of the metal clip on the float assembly until these two dimensions are achieved. \\ | The actual adjustments are made by carefully bending the two tabs of the metal clip on the float assembly until these two dimensions are achieved. \\ | ||
| - | |Setting 'fully closed' | + | |Setting 'fully closed' |
| |{{: | |{{: | ||
| Line 548: | Line 534: | ||
| The valve should be fully closed with a measurement of .63" | The valve should be fully closed with a measurement of .63" | ||
| - | {{: | + | {{: |
| ====== Heat Spacer ====== | ====== Heat Spacer ====== | ||
| [[techtalk: | [[techtalk: | ||
| + | |||
| ====== Vacuum Ports (83-up) ====== | ====== Vacuum Ports (83-up) ====== | ||
| **VOES port**. \\ | **VOES port**. \\ | ||
| Line 577: | Line 564: | ||
| The line to the gas tank on XLX and XLH models is hooked to the vent tube on the bottom of the tank. \\ | The line to the gas tank on XLX and XLH models is hooked to the vent tube on the bottom of the tank. \\ | ||
| On XLS models, it's hooked to the vent on the gas filler neck. \\ | On XLS models, it's hooked to the vent on the gas filler neck. \\ | ||
| - | |1983 Keihin butterfly - single vacuum port. ((photo by RatRodder of the XLFORUM | + | |1983 Keihin butterfly - single vacuum port. ((photo by RatRodder of the XLFORUM |
| |{{: | |{{: | ||
| Line 585: | Line 572: | ||
| ===== Altitude and Ambient Temps ===== | ===== Altitude and Ambient Temps ===== | ||
| - | A Carb works by mixing air and fuel into a vaporous mixture. We want the ideal mixture so the bike runs well. ((stevo of the XLFORUM | + | A Carb works by mixing air and fuel into a vaporous mixture. We want the ideal mixture so the bike runs well. ((stevo of the XLFORUM |
| Unfortunately it's not quite simple as a carburetor mixes air by a set volume to set the amount of fuel. \\ | Unfortunately it's not quite simple as a carburetor mixes air by a set volume to set the amount of fuel. \\ | ||
| The amount of oxygen density in that set amount of air varies and this is what gives variations in mixture due to differing conditions. \\ | The amount of oxygen density in that set amount of air varies and this is what gives variations in mixture due to differing conditions. \\ | ||
| Line 614: | Line 601: | ||
| The opposite is also true. \\ | The opposite is also true. \\ | ||
| - | Hotter Air = Less Oxygen → Richer Mix ((stevo of the XLFORUM | + | Hotter Air = Less Oxygen → Richer Mix ((stevo of the XLFORUM |
| Colder Air = More Oxygen → Leaner Mix \\ | Colder Air = More Oxygen → Leaner Mix \\ | ||
| Higher Barometric Pressure (Low Altitude) = More Oxygen → Leaner Mix \\ | Higher Barometric Pressure (Low Altitude) = More Oxygen → Leaner Mix \\ | ||
| Line 620: | Line 607: | ||
| Higher Humidity = Less Oxygen → Richer Mix \\ | Higher Humidity = Less Oxygen → Richer Mix \\ | ||
| Lower Humidity = More Oxygen → Leaner Mix \\ | Lower Humidity = More Oxygen → Leaner Mix \\ | ||
| + | |||
| ===== Fuel overflow ===== | ===== Fuel overflow ===== | ||
| - | The overflow tube is a safety feature in case the float needle does not prevent flow and the bowl gets full. ((IXL2Relax of the XLFORUM | + | The overflow tube is a safety feature in case the float needle does not prevent flow and the bowl gets full. ((IXL2Relax of the XLFORUM |
| It prevents the fuel from being pushed out of the carb float bowl, into the carb / manifold, and filling the cylinders (or crankcase) with the overflowing fuel. \\ | It prevents the fuel from being pushed out of the carb float bowl, into the carb / manifold, and filling the cylinders (or crankcase) with the overflowing fuel. \\ | ||
| Line 630: | Line 618: | ||
| Then watch for gas to rise in the hose with the engine running at different throttle levels. \\ | Then watch for gas to rise in the hose with the engine running at different throttle levels. \\ | ||
| - | {{: | + | {{: |
| **Check for**: \\ | **Check for**: \\ | ||
| * **Worn or stuck or improper float valve**. | * **Worn or stuck or improper float valve**. | ||
| - | * If gas overflows when you turn the gas on, rap the side of the float bowl sharply with a small wrench or pliers. \\ This may dis-lodge what is causing the hang up. If that does not work, remove the float bowl and float and do a close inspection. ((piniongear of the XLFORUM | + | * If gas overflows when you turn the gas on, rap the side of the float bowl sharply with a small wrench or pliers. \\ This may dis-lodge what is causing the hang up. If that does not work, remove the float bowl and float and do a close inspection. ((piniongear of the XLFORUM |
| - | * Replacing the float needle is usually one of the first thoughts but that may not always be the answer. \\ If you replaced the float needle with a new one from a kit, that could be the problem. Try re-installing the old one. \\ It's good to check the float height every time you remove the float bowl, as the last step before re-installing. \\ It is too easy to touch the float a little too hard and set it off. ((IronMick of the XLFORUM | + | * Replacing the float needle is usually one of the first thoughts but that may not always be the answer. \\ If you replaced the float needle with a new one from a kit, that could be the problem. Try re-installing the old one. \\ It's good to check the float height every time you remove the float bowl, as the last step before re-installing. \\ It is too easy to touch the float a little too hard and set it off. ((IronMick of the XLFORUM |
| - | * If the problem is crud, then it can often be fixed at least temporarily by partially emptying the float bowl. ((Ironmick of the XLFORUM | + | * If the problem is crud, then it can often be fixed at least temporarily by partially emptying the float bowl. ((Ironmick of the XLFORUM |
| * **Damage or debris around valve seat**. | * **Damage or debris around valve seat**. | ||
| - | * **Too high float level**. | + | * **Too high float level**. |
| - | * See [[techtalk: | + | |
| * **Worn float mounting tabs, float pin or loose float retaining screw**. | * **Worn float mounting tabs, float pin or loose float retaining screw**. | ||
| * **Cracked or damaged overflow tube in the float bowl**. | * **Cracked or damaged overflow tube in the float bowl**. | ||
| - | * Check for a leak at the bottom of the stand tube in the float bowl. ((Wedge of the XLFORUM | + | * Check for a leak at the bottom of the stand tube in the float bowl. ((Wedge of the XLFORUM |
| * **Damaged bowl gasket / O-ring**. | * **Damaged bowl gasket / O-ring**. | ||
| * **Loose bowl screws**. | * **Loose bowl screws**. | ||
| Line 650: | Line 637: | ||
| **Check for**: \\ | **Check for**: \\ | ||
| + | * **Float setting too low**. See [[techtalk: | ||
| * **Improper idle mixture adjustment**: | * **Improper idle mixture adjustment**: | ||
| * **Damaged mixture screw**. | * **Damaged mixture screw**. | ||
| Line 655: | Line 643: | ||
| * **Clogged slow jet**. | * **Clogged slow jet**. | ||
| * **Loose slow jet**. | * **Loose slow jet**. | ||
| - | * **Air leaks**. | + | * **Air leaks**. See [[techtalk: |
| * **Excess or sloppy fuel from accelerator pump**. | * **Excess or sloppy fuel from accelerator pump**. | ||
| * **Improper fast idle adjustment on 79-up carbs**: | * **Improper fast idle adjustment on 79-up carbs**: | ||
| - | * A fast idle can be caused by the idle not being set when the bike is HOT. ((ryder rick of the XLFORUM | + | * A fast idle can be caused by the idle not being set when the bike is HOT. ((ryder rick of the XLFORUM |
| * A fast idle can also be caused by an advance mechanism that is not functioning correctly. \\ | * A fast idle can also be caused by an advance mechanism that is not functioning correctly. \\ | ||
| * **Mechanical issues with choke or throttle shaft / parts**. | * **Mechanical issues with choke or throttle shaft / parts**. | ||
| Line 664: | Line 652: | ||
| * Insure the fuel hose isn't touching a head / cylinder to add extra heat to the fuel. | * Insure the fuel hose isn't touching a head / cylinder to add extra heat to the fuel. | ||
| * Consider installing a heat spacer between the carb and manifold. \\ See [[techtalk: | * Consider installing a heat spacer between the carb and manifold. \\ See [[techtalk: | ||
| - | |||
| ===== Poor acceleration ===== | ===== Poor acceleration ===== | ||
| Line 672: | Line 659: | ||
| * **Clogged bypass (idle transfer) ports**. | * **Clogged bypass (idle transfer) ports**. | ||
| * **Clogged or too small of a slow jet / bleed tube**. | * **Clogged or too small of a slow jet / bleed tube**. | ||
| - | * **Float setting too low**. | + | * **Float setting too low**. See [[techtalk: |
| - | * See [[techtalk: | + | |
| ===== Hard Starting ===== | ===== Hard Starting ===== | ||
| **Check for**: \\ | **Check for**: \\ | ||
| - | * **Improper idle mixture adjustment**: | + | * **Improper idle mixture adjustment**: |
| * **Choke not adjusted properly / not operating properly**. | * **Choke not adjusted properly / not operating properly**. | ||
| * **Clogged jets or internal passages in the carb.**. | * **Clogged jets or internal passages in the carb.**. | ||
| - | * **Wrong float setting**. | + | * **Wrong float setting**. |
| - | * See [[techtalk: | + | |
| * **Fuel valve on tank not turned on**. | * **Fuel valve on tank not turned on**. | ||
| * **Loose bowl screws**. | * **Loose bowl screws**. | ||
| Line 687: | Line 672: | ||
| ===== Rich or Lean? ===== | ===== Rich or Lean? ===== | ||
| - | A lean idle mixture will have idle hang before settling in after a throttle blip. ((xl2000883/ | + | A lean idle mixture will have idle hang before settling in after a throttle blip. ((xl2000883/ |
| A rich idle mixture will have idle dip low and then increase after a throttle blip. \\ | A rich idle mixture will have idle dip low and then increase after a throttle blip. \\ | ||
| A good setting will have rpm drop to idle and just sit there. \\ | A good setting will have rpm drop to idle and just sit there. \\ | ||
| Line 693: | Line 678: | ||
| ===== Running Lean ===== | ===== Running Lean ===== | ||
| - | The main causes of carb farts are lean mixture, retarded spark and tight pushrod clearances. ((IronMick of the XLFORUM | + | The main causes of carb farts are lean mixture, retarded spark and tight pushrod clearances. ((IronMick of the XLFORUM |
| During the mid 1979 model season, HD makes a recommendation to dealers for corrective measures regarding the carburetion and [[techtalk: | During the mid 1979 model season, HD makes a recommendation to dealers for corrective measures regarding the carburetion and [[techtalk: | ||
| Line 704: | Line 689: | ||
| * **Symptoms**: | * **Symptoms**: | ||
| * Spitting / backfire thru the carb. | * Spitting / backfire thru the carb. | ||
| - | * Inconsistent idle. ((IronMick of the XLFORUM | + | * Inconsistent idle. ((IronMick of the XLFORUM |
| - | * Slow return to idle. ((IronMick of the XLFORUM | + | * Slow return to idle. ((IronMick of the XLFORUM |
| * Increasing idle. \\ Once it heats up a bit the leak starts and without countering it with more gas it dies. \\ If the mixture thins, the engine starves and tries to pull more fuel and the leaner it gets the faster the idle until it quits. | * Increasing idle. \\ Once it heats up a bit the leak starts and without countering it with more gas it dies. \\ If the mixture thins, the engine starves and tries to pull more fuel and the leaner it gets the faster the idle until it quits. | ||
| - | * Backfiring can be caused by bad plugs. ((Hopper of the XLFORUM | + | * Backfiring can be caused by bad plugs. ((Hopper of the XLFORUM |
| - | * Air / exhaust gas blowing out the carb is a timing issue. An intake valve may be open when it should be closed. ((IronMick of the XLFORUM | + | * Air / exhaust gas blowing out the carb is a timing issue. An intake valve may be open when it should be closed. ((IronMick of the XLFORUM |
| * Running hot can be caused by vacuum leaks or bad ignition events. | * Running hot can be caused by vacuum leaks or bad ignition events. | ||
| * **Causes**: | * **Causes**: | ||
| Line 719: | Line 704: | ||
| * Stopped up or poor flowing air cleaner. Make sure it's getting plenty of air. \\ If you are running the 72 air cleaner backing plate, the outside of it should fit to the size of the air cleaner. \\ The 77 and later backing plates had an air horn and they weren' | * Stopped up or poor flowing air cleaner. Make sure it's getting plenty of air. \\ If you are running the 72 air cleaner backing plate, the outside of it should fit to the size of the air cleaner. \\ The 77 and later backing plates had an air horn and they weren' | ||
| * Retarded spark timing is usually from a worn out auto advance unit in the ignition allowing too much retard at idle. | * Retarded spark timing is usually from a worn out auto advance unit in the ignition allowing too much retard at idle. | ||
| - | * Running the ignition timing slightly advanced is good. ((oldnavy of the XLFORUM | + | * Running the ignition timing slightly advanced is good. ((oldnavy of the XLFORUM |
| * Pushrod adjustment can also cause it and is easy to check. | * Pushrod adjustment can also cause it and is easy to check. | ||
| * **Testing for air leaks**. | * **Testing for air leaks**. | ||
| Line 727: | Line 712: | ||
| * Propane is the cleanest choice. | * Propane is the cleanest choice. | ||
| * You have to spray a lot of WD-40 and it will leaves a mess. | * You have to spray a lot of WD-40 and it will leaves a mess. | ||
| - | * For a test, spray some into the air cleaner. \\ The idle speed will go down, perhaps stall the engine, right away. ((IronMick of the XLFORUM | + | * For a test, spray some into the air cleaner. \\ The idle speed will go down, perhaps stall the engine, right away. ((IronMick of the XLFORUM |
| * If there is a leak you will get a slow down of the idle speed. | * If there is a leak you will get a slow down of the idle speed. | ||
| * Technically, | * Technically, | ||
| * The propane is nice and neat, and has finer particles so it should find smaller leaks. | * The propane is nice and neat, and has finer particles so it should find smaller leaks. | ||
| - | * If the idle raises on it's own then let the engine warm up before doing the test. ((brianbbs67 of the XLFORUM | + | * If the idle raises on it's own then let the engine warm up before doing the test. ((brianbbs67 of the XLFORUM |
| ===== Poor road performance ===== | ===== Poor road performance ===== | ||
| Line 795: | Line 779: | ||
| ====== Helpful Links ====== | ====== Helpful Links ====== | ||
| **Video**: \\ | **Video**: \\ | ||
| - | Here are some excellent videos of servicing the pre-CV Keihin Butterfly carbs: ((Used by permission - SportsterPaul at the XLForum - http:// | + | Here are some excellent videos of servicing the pre-CV Keihin Butterfly carbs: ((Used by permission - SportsterPaul at the XLForum - https://www.xlforum.net/ |
| * [[https:// | * [[https:// | ||
