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techtalk:ref:engmech04k [2020/10/09 02:24] hippysmack [Breather Valves (1957-Up)] |
techtalk:ref:engmech04k [2023/12/20 22:22] (current) hippysmack |
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| 1957-E1984 engines incorporated an oil slinger (spinning gear or washer on the generator drive gear) to separate oil from air before running to the vent tube. \\ | 1957-E1984 engines incorporated an oil slinger (spinning gear or washer on the generator drive gear) to separate oil from air before running to the vent tube. \\ | ||
| - | **1957-1976 models**: ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=cam+chest+breather)) \\ | + | **1957-1976 models**: ((Hopper of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/74149-engine-breather-101-crankcase-vent-101?t=518948&highlight=cam+chest+breather)) \\ |
| There is a timed breather valve built into the oil pump drive, which vents both oil and crankcase pressure into the cam timing chest. \\ | There is a timed breather valve built into the oil pump drive, which vents both oil and crankcase pressure into the cam timing chest. \\ | ||
| A six-inch metal tube hanging down from the timing cover near the generator drive, at the 6 o’clock position vents that controlled pressure to atmosphere. \\ | A six-inch metal tube hanging down from the timing cover near the generator drive, at the 6 o’clock position vents that controlled pressure to atmosphere. \\ | ||
| Line 20: | Line 20: | ||
| **The 1972-1976** breather valve opens 20°-25° (ATDC) and closes 85°-90° (ABDC), less duration than the 57-71 breather. \\ | **The 1972-1976** breather valve opens 20°-25° (ATDC) and closes 85°-90° (ABDC), less duration than the 57-71 breather. \\ | ||
| + | |Left is the unmodified 1/4 speed R \\ valve. Right is the 1000 stock.|R model is the left one.| | ||
| + | |{{:techtalk:ih:engmech:cc_flow_4_by_dr_dick.jpg?direct&200|}}|{{:techtalk:ih:engmech:cc_flow_5_by_dr_dick.jpg?direct&300|}}| | ||
| - | **1977-78 models only**: ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=cam+chest+breather)) \\ | + | **1977-78 models only**: ((Hopper of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/74149-engine-breather-101-crankcase-vent-101?t=518948&highlight=cam+chest+breather)) \\ |
| The timed breather on the oil pump drive was dropped. \\ | The timed breather on the oil pump drive was dropped. \\ | ||
| Without the breather gear that means you have less control of the oil / air density in the crankcase. \\ | Without the breather gear that means you have less control of the oil / air density in the crankcase. \\ | ||
| Line 28: | Line 30: | ||
| The valve is installed on the outboard side of the gearcase and inside a threaded fitting with no oil separation drain back hole. \\ | The valve is installed on the outboard side of the gearcase and inside a threaded fitting with no oil separation drain back hole. \\ | ||
| - | **1979-Early 1982 models**: ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=cam+chest+breather)) \\ | + | **1979-Early 1982 models**: ((Hopper of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/74149-engine-breather-101-crankcase-vent-101?t=518948&highlight=cam+chest+breather)) \\ |
| The external foo-foo valve and the six-inch metal vent tube at the front of the timing cover were done away with. \\ | The external foo-foo valve and the six-inch metal vent tube at the front of the timing cover were done away with. \\ | ||
| Instead, a one-way reed valve (assembly, 26909-79A) was built inside the timing cover. \\ | Instead, a one-way reed valve (assembly, 26909-79A) was built inside the timing cover. \\ | ||
| Line 56: | Line 58: | ||
| Previously, these bolts were just used to mount the carb and air cleaner to the heads. \\ | Previously, these bolts were just used to mount the carb and air cleaner to the heads. \\ | ||
| The new breather system uses one-way umbrella valves in the rocker boxes. \\ | The new breather system uses one-way umbrella valves in the rocker boxes. \\ | ||
| - | These exit crankcase vapors through vents in the top of the cylinder head into the carb mouth to be burnt. ((FoxsterUK of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=wet+sumping)) \\ | + | These exit crankcase vapors through vents in the top of the cylinder head into the carb mouth to be burnt. ((FoxsterUK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/74149-engine-breather-101-crankcase-vent-101?t=518948&highlight=wet+sumping)) \\ |
| On each piston downstroke, crankcase pressure (air and oil mist) is routed up the pushrod tubes into the rocker box. \\ | On each piston downstroke, crankcase pressure (air and oil mist) is routed up the pushrod tubes into the rocker box. \\ | ||
| Collected air pressure and oil mist in each rocker box is routed up into a sealed cavity in the lower portion of the box. \\ | Collected air pressure and oil mist in each rocker box is routed up into a sealed cavity in the lower portion of the box. \\ | ||
| Line 81: | Line 83: | ||
| So the head vent also doubles as a back vent to help CC vacuum drain the sealed cavity on piston upstroke. \\ | So the head vent also doubles as a back vent to help CC vacuum drain the sealed cavity on piston upstroke. \\ | ||
| - | {{:techtalk:ref:engmech:umbrella_valve_by_phillober_labeled_by_hippysmack.jpg?direct&300|}} ((photo by Phillober of the XLFORUM, labeled by Hippysmack http://xlforum.net/forums/showthread.php?p=3345764#post3345764)) | + | {{:techtalk:ref:engmech:umbrella_valve_by_phillober_labeled_by_hippysmack.jpg?direct&300|}} ((photo by Phillober of the XLFORUM, labeled by Hippysmack https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/116696-phillober-s-1250-conversion-thread-pic-heavy/page11#post2487181)) |
| {{:techtalk:evo:oil:crankcase_pressure_separation_chambe_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) \\ | {{:techtalk:evo:oil:crankcase_pressure_separation_chambe_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) \\ | ||
| Line 97: | Line 99: | ||
| The new bolts are the same thread size as previous. \\ | The new bolts are the same thread size as previous. \\ | ||
| But instead of a simple hex, it also has a shoulder past the hex for an O-ring to be fitted between the hex head and the air cleaner. \\ | But instead of a simple hex, it also has a shoulder past the hex for an O-ring to be fitted between the hex head and the air cleaner. \\ | ||
| - | The breathing system is functionally the same as 91-03 with the one-way umbrella valves in the rocker boxes. \\ These exit crankcase vapors through vents in the top of the cylinder head and into the carb mouth to be burnt. ((FoxsterUK of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=wet+sumping)) \\ | + | The breathing system is functionally the same as 91-03 with the one-way umbrella valves in the rocker boxes. \\ These exit crankcase vapors through vents in the top of the cylinder head and into the carb mouth to be burnt. ((FoxsterUK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/74149-engine-breather-101-crankcase-vent-101?t=518948&highlight=wet+sumping)) \\ |
| On each piston downstroke, crankcase pressure (air and oil mist) is routed up the pushrod tubes into the rocker box. \\ | On each piston downstroke, crankcase pressure (air and oil mist) is routed up the pushrod tubes into the rocker box. \\ | ||
| Collected air pressure and oil mist in each rocker box is routed up into the breather valve unit in the lower portion of the box. \\ | Collected air pressure and oil mist in each rocker box is routed up into the breather valve unit in the lower portion of the box. \\ | ||
| Line 119: | Line 121: | ||
| It has to open with downstrokes and close (completely) with upstrokes. \\ | It has to open with downstrokes and close (completely) with upstrokes. \\ | ||
| - | | Breather Valves ((photo by DK Custom of the XLFORUM http://xlforum.net/forums/showthread.php?t=1582019&page=11)) | View of one cut open. ((photos by Bored now of the XLFORUM, annotated by Hippysmack http://xlforum.net/forums/showthread.php?p=5761087#post5761087)) || | + | | Breather Valves ((photo by DK Custom of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/efi-sportster-motorcycle-talk-2007-and-up/145738-sportster-winter-makeover/page11?t=1582019&page=11)) | View of one cut open. ((photos by Bored now of the XLFORUM, annotated by Hippysmack https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-general-discussion-and-problems/197352-oil-cap-problems-bikers-choice-02-073/page2#post4317318)) || |
| |{{:techtalk:evo:oil:breather_valves_by_dk_custom.jpg?direct&300|}}|{{:techtalk:ref:engmech:04_up_breather_1a_by_bored_now_annotated_by_hippysmack.jpg?direct&300|}}|{{:techtalk:ref:engmech:04_up_breather_2a_by_bored_now_annotated_by_hippysmack.jpg?direct&300|}}| | |{{:techtalk:evo:oil:breather_valves_by_dk_custom.jpg?direct&300|}}|{{:techtalk:ref:engmech:04_up_breather_1a_by_bored_now_annotated_by_hippysmack.jpg?direct&300|}}|{{:techtalk:ref:engmech:04_up_breather_2a_by_bored_now_annotated_by_hippysmack.jpg?direct&300|}}| | ||
| - | |The mesh can become saturated with oil. ((photo by dieselvette of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=28))|Oil drain hole. ((photo by dieselvette of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=30))|Installed upright as shown. ((photo by dieselvette of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=30))| | + | |The mesh can become saturated with oil. ((photo by dieselvette of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/197307-sportster-crankcase-pressure-engine-breathing-wetsumping-and-mods/page28?t=2073932&page=28))|Oil drain hole. ((photo by dieselvette of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/197307-sportster-crankcase-pressure-engine-breathing-wetsumping-and-mods/page28?t=2073932&page=28))|Installed upright as shown. ((photo by dieselvette of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/197307-sportster-crankcase-pressure-engine-breathing-wetsumping-and-mods/page28?t=2073932&page=28))| |
| |{{:techtalk:ref:engmech:04_up_breather_valve_1_by_dieselvette.jpg?direct&300|}}|{{:techtalk:ref:engmech:04_up_breather_valve_2_by_dieselvette.jpg?direct&300|}}|{{:techtalk:ref:engmech:04_up_breather_valve_3_by_dieselvette.jpg?direct&300|}}| | |{{:techtalk:ref:engmech:04_up_breather_valve_1_by_dieselvette.jpg?direct&300|}}|{{:techtalk:ref:engmech:04_up_breather_valve_2_by_dieselvette.jpg?direct&300|}}|{{:techtalk:ref:engmech:04_up_breather_valve_3_by_dieselvette.jpg?direct&300|}}| | ||
| - | 57-76 engines breath and scavenge oil from the same oil galley in the rear of the sump. \\ | ||
| - | <blockquote>The shallow sump, timed breather system, comes from the aviation world of old. ((mrmom9r of the XLFORUM http://xlforum.net/forums/showthread.php?t=1204854&page=4)) \\ | ||
| - | Piston driven aircraft had to be able to evacuate the oil from the crankcase regardless of engine altitude and that system does that. \\ | ||
| - | At the time Harley adapted that system they were copying the highest engine technology of the day. \\ | ||
| - | They just took too long to abandon it as technology advanced. \\ | ||
| - | Documents from HD Racing from the period show no HP gain between the 2 ironhead systems when the breather is properly timed ( which didn't happen a lot). \\ | ||
| - | </blockquote> | ||
| - | The rotary breather valve is integrated with the oil pump. The gear on top of the valve also operates the oil pump. \\ | ||
| - | The breather valve connects the flywheel area to the gearcase. \\ | ||
| - | |||
| - | The rotary breather valve functions to relieve pressure in the crankcase caused by the downstroke of the pistons and it controls the flow of oil in the lubrication system. \\ | ||
| - | It is timed to engine rotation and opens on the downstroke of the pistons. ((1960 HD FSM pg 3a-15)) \\ | ||
| - | This allows crankcase exhaust air pressure to expel the scavenge oil from the crankcase breather oil trap into the gearcase. \\ | ||
| - | The breather valve then closes on piston upstroke, creating vacuum in the crankcase. \\ | ||
| - | Crankcase exhaust air from the gearcase is sent out the breather tube. \\ | ||
| - | Any oil still in suspension with the air on the way to the breather tube is separated by an oil slinger on the generator drive gear. \\ | ||
| - | |||
| - | |Left is the unmodified 1/4 speed R \\ valve. Right is the 1000 stock.|R model is the left one.| | ||
| - | |{{:techtalk:ih:engmech:cc_flow_4_by_dr_dick.jpg?direct&200|}}|{{:techtalk:ih:engmech:cc_flow_5_by_dr_dick.jpg?direct&300|}}| | ||
