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techtalk:evo:engmech07 [2021/06/19 00:05]
hippysmack [Buell (XB type) Breather Valve]
techtalk:evo:engmech07 [2023/12/26 20:23] (current)
hippysmack
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 86-90 engines vent through a valve in the cam cover. \\ 86-90 engines vent through a valve in the cam cover. \\
 91 and up engines vent through a valve in each rocker box and out the hollow breather bolts in each head to the air cleaner. \\ 91 and up engines vent through a valve in each rocker box and out the hollow breather bolts in each head to the air cleaner. \\
- 
  
 ====== Late 1984-1990 Sportster Breather Valve ====== ====== Late 1984-1990 Sportster Breather Valve ======
- 
 **An important note**: \\ **An important note**: \\
 Factory engine breather valves on all Evo Sportsters are inside the engine. \\ Factory engine breather valves on all Evo Sportsters are inside the engine. \\
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   * 1986-1990 engines continued the breather baffle tube system (implemented in L1984) incorporated into the cam cover in the area behind the oil filter.   * 1986-1990 engines continued the breather baffle tube system (implemented in L1984) incorporated into the cam cover in the area behind the oil filter.
-  * The baffle tube mounts into the cam cover and the rubber umbrella installs into the center of the baffle tube. ((Gary E of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2071387&​page=8))+  * The baffle tube mounts into the cam cover and the rubber umbrella installs into the center of the baffle tube. ((Gary E of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-bottom-end/​195092-rigid-evo-oil-check-ball-spring/​page8?​t=2071387&​page=8))
   * On each piston downstroke, crankcase pressure (air and oil mist) is routed to the breather baffle at the front of the cam case.   * On each piston downstroke, crankcase pressure (air and oil mist) is routed to the breather baffle at the front of the cam case.
   * Oil is separated from the air pressure by the one-way umbrella valve.   * Oil is separated from the air pressure by the one-way umbrella valve.
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     * The air is then routed into the rear of the air cleaner via an oil hose to the cam cover.     * The air is then routed into the rear of the air cleaner via an oil hose to the cam cover.
  
-**Umbrella check valve comparison**:​ ((Gary E of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2071387&​page=8)) \\+**Umbrella check valve comparison**:​ ((Gary E of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-bottom-end/​195092-rigid-evo-oil-check-ball-spring/​page8?​t=2071387&​page=8)) \\
 Outside diameter: \\ Outside diameter: \\
 26856-82 - 1.25" \\ 26856-82 - 1.25" \\
 26856-89 - 1.0" \\ 26856-89 - 1.0" \\
  
-Edge thickness (1/8" in average): ((Gary E of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2071387&​page=8)) \\+Edge thickness (1/8" in average): ((Gary E of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-bottom-end/​195092-rigid-evo-oil-check-ball-spring/​page8?​t=2071387&​page=8)) \\
 26856-82 - 0.036" \\ 26856-82 - 0.036" \\
 26856-89 - 0.041" \\ 26856-89 - 0.041" \\
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 |{{:​techtalk:​evo:​oil:​umbrella_valve_by_gary_e.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​breather_baffle_tube_by_gary_e.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​86_crankcase_vent_3_by_norsexl.jpg?​direct&​300|}}| |{{:​techtalk:​evo:​oil:​umbrella_valve_by_gary_e.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​breather_baffle_tube_by_gary_e.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​86_crankcase_vent_3_by_norsexl.jpg?​direct&​300|}}|
-|  Umbrella (check) Valves \\ L - (26856-82), R - (26856-89) ((photo by Gary E of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2071387&​page=8)) ​ |  Breather Baffle Tube (26917-84) ((photo by Gary E of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2071387&​page=8http:​//xlforum.net/forums/showthread.php?​t=2071387&​page=8)) ​ |  Cap, tube and umbrella ((photo by norseXL of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=72099&​page=25)) ​ |+|  Umbrella (check) Valves \\ L - (26856-82), R - (26856-89) ((photo by Gary E of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-bottom-end/​195092-rigid-evo-oil-check-ball-spring/​page8?​t=2071387&​page=8)) ​ |  Breather Baffle Tube (26917-84) ((photo by Gary E of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/195092-rigid-evo-oil-check-ball-spring/page8?​t=2071387&​page=8)) ​ |  Cap, tube and umbrella ((photo by norseXL of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-bottom-end/​36799-installing-the-ultimate-crankcase-vent-%C2%93how-to%C2%94/​page25?​t=72099&​page=25)) ​ |
  
 This looks like a good factory alternative replacement umbrella valve that comes in a replacement kit for Twin Cams. \\ This looks like a good factory alternative replacement umbrella valve that comes in a replacement kit for Twin Cams. \\
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 |{{:​techtalk:​evo:​engmech:​umbrella_valve_by_crb2855.jpg?​direct&​300|}}| |{{:​techtalk:​evo:​engmech:​umbrella_valve_by_crb2855.jpg?​direct&​300|}}|
-|  1999 Dyna Twin Cam style umbrella (26858-99) ((photo by crb2855 of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5884041#post5884041))  |+|  1999 Dyna Twin Cam style umbrella (26858-99) ((photo by crb2855 of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-bottom-end/​195092-rigid-evo-oil-check-ball-spring/​page6#post4484031))  |
  
 |{{:​techtalk:​evo:​oil:​89_cam_cover_1_by_bryan350.jpg?​direct&​250|}}|{{:​techtalk:​evo:​oil:​89_cam_cover_2_by_bryan350.jpg?​direct&​250|}}|{{:​techtalk:​evo:​oil:​89_cam_cover_3_by_bryan350.jpg?​direct&​250|}}| |{{:​techtalk:​evo:​oil:​89_cam_cover_1_by_bryan350.jpg?​direct&​250|}}|{{:​techtalk:​evo:​oil:​89_cam_cover_2_by_bryan350.jpg?​direct&​250|}}|{{:​techtalk:​evo:​oil:​89_cam_cover_3_by_bryan350.jpg?​direct&​250|}}|
-|  89 cam cover with breather baffle tube attached (it should be tight but still pull out) ((photos by Bryan350 of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=1712011)) ​ |||  +|  89 cam cover with breather baffle tube attached (it should be tight but still pull out) ((photos by Bryan350 of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-era-specific-and-model-specific/​frame-mount-evo-sportster-talk-1986-2003-models/​159628-cam-cover-question?​t=1712011)) ​ ||| 
- +
-**Testing the L84-90 umbrella valve**: \\ +
-A working valve should help reduce oil mist. ((Four Speed of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5745528#​post5745528)) \\ +
-Since it's a one-way valve, air goes out but doesn'​t come back in. \\ +
- +
-To make sure the umbrella valve is still working; \\  +
-Before you position the hose, use a bit of clean pipe and blow gently through the breather. \\ +
-It should close the valve and stop air flow. +
-You may have to find an aftermarket replacement if the valve is shot as OEM replacements are hard to come by now. \\ +
-The 5 speed ones do not fit.+
  
 ====== 1991-2003 Sportster Breather Valve ====== ====== 1991-2003 Sportster Breather Valve ======
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   * In 1991, along with the 5-speed transmission,​ the MoCo moved the crankcase breathing from the cam box cover outlet to breather bolts in the heads. ​ \\ Previously, these bolts were just used to mount the carb and air cleaner to the heads. ​   * In 1991, along with the 5-speed transmission,​ the MoCo moved the crankcase breathing from the cam box cover outlet to breather bolts in the heads. ​ \\ Previously, these bolts were just used to mount the carb and air cleaner to the heads. ​
-  * The new breather system uses (2) one-way umbrella valves placed in the rocker boxes (1 each placed on the intake side). \\ These expel crankcase vapors through vents in the top of the cylinder head and into the carb to be burnt. ((FoxsterUK of the XLFORUM  ​http://​xlforum.net/​forums/showthread.php?​t=518948&​highlight=wet+sumping))+  * The new breather system uses (2) one-way umbrella valves ​(26856-89) ​placed in the rocker boxes (1 each placed on the intake side). \\ The part number was later updated to (26856-89A). \\ These expel crankcase vapors through vents in the top of the cylinder head and into the carb 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 (bypassing the falling oil from the rocker boxes).     * On each piston downstroke, crankcase pressure (air and oil mist) is routed up the pushrod tubes into the rocker box (bypassing the falling oil from the rocker boxes).
     * 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.
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 **Installation** \\ **Installation** \\
  
-  * The middle rocker box is symmetrically cast so that it can be used on the front or rear head. \\ And, there is a spot (seemingly) for two umbrellas. ((zenfrogmaster of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=382922)) +  * The middle rocker box is symmetrically cast so that it can be used on the front or rear head. \\ And, there is a spot (seemingly) for two umbrellas. ((zenfrogmaster of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-era-specific-and-model-specific/​frame-mount-evo-sportster-talk-1986-2003-models/​62904-rubbery-like-small-cap-on-middle-rocker-cover?​t=382922)) 
-  * **However, only one umbrella is used in each middle section**. \\ (only 2 umbrella valves are used in the entire engine.) ((Graywolf of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5703205#post5703205)) \\ +  * **However, only one umbrella is used in each middle section**. \\ (only 2 umbrella valves are used in the entire engine.) ((Graywolf of the XLFORUM ​https://www.xlforum.net/​forum/forum-functions/​sportsterpedia-com-admin/​181086-sportsterpedia-progress/​page12#post4237448)) \\ 
   * __Each umbrella is placed on the intake side on each head (only).__   * __Each umbrella is placed on the intake side on each head (only).__
   * It is not always green as in the pic below (depends on what brand you buy).   * It is not always green as in the pic below (depends on what brand you buy).
  
 |{{:​techtalk:​evo:​oil:​umbrella_valves_by_erik.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​umbrella_valve_by_phillober.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​umbrella_valve_locations_by_hippysmack.jpg?​direct&​300|}}| |{{:​techtalk:​evo:​oil:​umbrella_valves_by_erik.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​umbrella_valve_by_phillober.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​umbrella_valve_locations_by_hippysmack.jpg?​direct&​300|}}|
-|  Umbrella Valve (only 1 installed per rocker box) ((photo by Eric of the XLFORUM ​ http://​xlforum.net/​forums/showthread.php?t=382922)) ((photo by Phillober of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=3345764#post3345764))  ||  Umbrella Valve Installed Locations ((photo by Hippysmack)) ​ |+|  Umbrella Valve (only 1 installed per rocker box) ((photo by Eric of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-era-specific-and-model-specific/​frame-mount-evo-sportster-talk-1986-2003-models/​62904-rubbery-like-small-cap-on-middle-rocker-cover?t=382922)) ((photo by Phillober of the XLFORUM ​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))  ||  Umbrella Valve Installed Locations ((photo by Hippysmack)) ​ |
  
 |{{:​techtalk:​evo:​oil:​head_breather_holes_1_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​head_breather_holes_2_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​head_breather_holes_3_by_hippysmack.jpg?​direct&​300|}}| |{{:​techtalk:​evo:​oil:​head_breather_holes_1_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​head_breather_holes_2_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​head_breather_holes_3_by_hippysmack.jpg?​direct&​300|}}|
 |  91-03 crankcase ventilation is done through the hole with the wire tie. ((photos by Hippysmack)) ​ ||| |  91-03 crankcase ventilation is done through the hole with the wire tie. ((photos by Hippysmack)) ​ |||
- 
  
 ====== 2004-Present Sportster Breather Valve ====== ====== 2004-Present Sportster Breather Valve ======
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   * In 2004 the MoCo made some changes to the umbrella valve configuration. \\ The umbrella was retained but now inside a plastic housing with a pre-umbrella oil separating screen. \\ Each '​breather valve' is assembled into a plastic fitting that is sealed over the outlet hole in the lower rocker box to the head breather bolt. \\  The new breather valves were also accompanied with new style hollow air cleaner mounting bolts for the pressure to escape.   * In 2004 the MoCo made some changes to the umbrella valve configuration. \\ The umbrella was retained but now inside a plastic housing with a pre-umbrella oil separating screen. \\ Each '​breather valve' is assembled into a plastic fitting that is sealed over the outlet hole in the lower rocker box to the head breather bolt. \\  The new breather valves were also accompanied with new style hollow air cleaner mounting bolts for the pressure to escape.
   * 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.   * 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.
-  * 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 1991-2003 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 (bypassing the falling oil from the rocker boxes).     * On each piston downstroke, crankcase pressure (air and oil mist) is routed up the pushrod tubes into the rocker box (bypassing the falling oil from the rocker boxes).
     * 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 136: Line 123:
 (as in there is one for the front and a different one for the rear) \\ (as in there is one for the front and a different one for the rear) \\
  
-Each one consists of a poly fiber over a rubber flap. ((AnaChris of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=1881344&​highlight=crankcase+breather&​page=2)) \\+Each one consists of a poly fiber over a rubber flap. ((AnaChris of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​175336-crankcase-breather-kit-with-stock-air-cleaner/​page2?​t=1881344&​highlight=crankcase+breather&​page=2)) \\
 The fiber pieces are the same as the brown Scotchbrite pads that are sold in the body section of auto parts stores. \\ The fiber pieces are the same as the brown Scotchbrite pads that are sold in the body section of auto parts stores. \\
-You can cut your own put them in the breather valves. They are aluminum oxide and won't hurt the engine. ((Sweet Terry Smoove of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?p=5127159&​highlight=rocker+box#​post5127159)) \\+You can cut your own put them in the breather valves. They are aluminum oxide and won't hurt the engine. ((Sweet Terry Smoove of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-motor-top-end/​174693-umbrella-valve-filters-necessary?​highlight=rocker+box#​post5127159)) \\
  
-|  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 ​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 ​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:​evo:​engmech:​04_up_breather_1_by_bored_now.jpg?​direct&​300|}}|{{:​techtalk:​evo:​engmech:​04_up_breather_2_by_bored_now.jpg?​direct&​300|}}| |{{:​techtalk:​evo:​oil:​breather_valves_by_dk_custom.jpg?​direct&​300|}}|{{:​techtalk:​evo:​engmech:​04_up_breather_1_by_bored_now.jpg?​direct&​300|}}|{{:​techtalk:​evo:​engmech:​04_up_breather_2_by_bored_now.jpg?​direct&​300|}}|
  
-|  Oil drain hole. ((photo by dieselvette of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2073932&​page=30)) ​ |  2006 Breather Valves ((photos by JackAttack of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=4435889))  ||+|  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/​page30?​t=2073932&​page=30)) ​ |  2006 Breather Valves ((photos by JackAttack of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-motor-top-end/​151682-2006-top-end-disassembly-pic-heavy#​post3232003))  ||
 |{{:​techtalk:​ref:​engmech:​04_up_breather_valve_2_by_dieselvette.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​06_rocker_box_removal_9_by_jackattack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​06_rocker_box_removal_8_by_jackattack.jpg?​direct&​300|}}| |{{:​techtalk:​ref:​engmech:​04_up_breather_valve_2_by_dieselvette.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​06_rocker_box_removal_9_by_jackattack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​06_rocker_box_removal_8_by_jackattack.jpg?​direct&​300|}}|
  
-|  2013 Breather Valves ((photos by chris_b_owens of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=1832762&​page=47)) ​ |||+|  2013 Breather Valves ((photos by chris_b_owens of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-styles/​cafe-racer-sportster-motorcycle-talk/​170788-my-2013-iron-883-cafe-build/​page47?​t=1832762&​page=47)) ​ |||
 |{{:​techtalk:​evo:​oil:​2013_crankcase_breather_2_by_chris_b_owens.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​2013_crankcase_breather_1_by_chris_b_owens.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​2013_crankcase_breather_4_by_chris_b_owens.jpg?​direct&​300|}}| |{{:​techtalk:​evo:​oil:​2013_crankcase_breather_2_by_chris_b_owens.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​2013_crankcase_breather_1_by_chris_b_owens.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​2013_crankcase_breather_4_by_chris_b_owens.jpg?​direct&​300|}}|
  
Line 171: Line 158:
 You can see the loading of oil on the mesh in the pics below. The shelving partitions in the lower end do help separate oil from air. \\ You can see the loading of oil on the mesh in the pics below. The shelving partitions in the lower end do help separate oil from air. \\
  
-With the 04 breather, a large portion of oil that gets past the umbrella can drain from the separator "​ladders"​ back into the rocker box. \\+With the 2004-up ​breather, a large portion of oil that gets past the umbrella can drain from the separator "​ladders"​ back into the rocker box. \\
 And some, usually in the form of mist will blow into the air cleaner. \\ And some, usually in the form of mist will blow into the air cleaner. \\
 Any oil that gets past the umbrella with the Buell breather will blow out the vent hose routed into the air filter. \\  Any oil that gets past the umbrella with the Buell breather will blow out the vent hose routed into the air filter. \\ 
-After some time it forms a puddle of condensed oil inside the airbox under the air filter. ((TPEHAK of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2073932&​page=93)) \\+After some time it forms a puddle of condensed oil inside the airbox under the air filter. ((TPEHAK 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/​page93?​t=2073932&​page=93)) \\
  
-{{:​techtalk:​evo:​engmech:​breather_valve_-_buell_17607-00y_by_tpehak_annotated_by_hippysmack.jpg?​direct&​500|}} ((drawing by TPEHAK of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2073932&​page=93)) {{:​techtalk:​evo:​engmech:​breather_valve_-_buell_17607-00y_pic1_by_tpehak_annotated_by_hippysmack.jpg?​direct&​400|}} ((photo by TPEHAK of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2073932&​page=93)) \\+{{:​techtalk:​evo:​engmech:​breather_valve_-_buell_17607-00y_by_tpehak_annotated_by_hippysmack.jpg?​direct&​500|}} ((drawing by TPEHAK 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/​page93?​t=2073932&​page=93)) {{:​techtalk:​evo:​engmech:​breather_valve_-_buell_17607-00y_pic1_by_tpehak_annotated_by_hippysmack.jpg?​direct&​400|}} ((photo by TPEHAK 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/​page93?​t=2073932&​page=93)) \\
    
-{{:​techtalk:​evo:​engmech:​breather_valve_-_buell_17607-00y_pic2_by_tpehak_annotated_by_hippysmack.jpg?​direct&​400|}} ((photo by TPEHAK of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2073932&​page=93))  +{{:​techtalk:​evo:​engmech:​breather_valve_-_buell_17607-00y_pic2_by_tpehak_annotated_by_hippysmack.jpg?​direct&​400|}} ((photo by TPEHAK 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/​page93?​t=2073932&​page=93))  
-{{:​techtalk:​evo:​engmech:​breather_valve_-_buell_17607-00y_pic3_by_tpehak_annotated_by_hippysmack.jpg?​direct&​400|}} ((photo by TPEHAK of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2073932&​page=93)) \\+{{:​techtalk:​evo:​engmech:​breather_valve_-_buell_17607-00y_pic3_by_tpehak_annotated_by_hippysmack.jpg?​direct&​400|}} ((photo by TPEHAK 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/​page93?​t=2073932&​page=93)) \\
 ====== Check the breather to gasket seal ====== ====== Check the breather to gasket seal ======
-There is an anomaly when it comes to the seal around the stock breather port under the rocker box. ((dieselvette of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5769573#post5769573))\\+There is an anomaly when it comes to the seal around the stock breather port under the rocker box. ((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/​page46#post4327896))\\
 The rocker box cover gasket is part of the seal for the breather port. \\ The rocker box cover gasket is part of the seal for the breather port. \\
 It's possible to make a mistake when installing the breathers into aftermarket gaskets and end up with oil puking out the breathers. \\ It's possible to make a mistake when installing the breathers into aftermarket gaskets and end up with oil puking out the breathers. \\
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 Also there is a bump to take up extra space next to the umbrella housing and it fits nicely in the hole of the gasket. \\ Also there is a bump to take up extra space next to the umbrella housing and it fits nicely in the hole of the gasket. \\
  
-{{:​techtalk:​evo:​engmech:​oem_gasket_1_by_dieselvette.jpg?​direct&​300|}} ((photo by dieselvette of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5769573#post5769573)) {{:​techtalk:​evo:​engmech:​oem_gasket_2_by_dieselvette.jpg?​direct&​300|}} ((photo by dieselvette of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5769573#post5769573)) +{{:​techtalk:​evo:​engmech:​oem_gasket_1_by_dieselvette.jpg?​direct&​300|}} ((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/​page46#post4327896)) {{:​techtalk:​evo:​engmech:​oem_gasket_2_by_dieselvette.jpg?​direct&​300|}} ((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/​page46#post4327896)) 
  
 **Using Cometic Rocker Box Gaskets**: \\ **Using Cometic Rocker Box Gaskets**: \\
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 To make this seal properly you would need the orange seal but you would only have the orange seal if you bought new breathers also. \\ To make this seal properly you would need the orange seal but you would only have the orange seal if you bought new breathers also. \\
  
-{{:​techtalk:​evo:​engmech:​cometic_gasket_1_by_dieselvette.jpg?​direct&​300|}} ((photo by dieselvette of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5769573#post5769573)) {{:​techtalk:​evo:​engmech:​cometic_gasket_2_by_dieselvette.jpg?​direct&​300|}} ((photo by dieselvette of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5769573#post5769573))+{{:​techtalk:​evo:​engmech:​cometic_gasket_1_by_dieselvette.jpg?​direct&​300|}} ((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/​page46#post4327896)) {{:​techtalk:​evo:​engmech:​cometic_gasket_2_by_dieselvette.jpg?​direct&​300|}} ((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/​page46#post4327896))
  
 ====== Head Breather Bolts ====== ====== Head Breather Bolts ======
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 Without the hole through the bolts, the engine can't breathe. \\ Without the hole through the bolts, the engine can't breathe. \\
  
-The size of the orifice in the hollow head breather bolts makes the crankcase pressure rise higher (or lower) in the process of expelling the gas. ((aswracing of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?p=4050323&​highlight=breather+bolts#​post4050323)) \\ +The size of the orifice in the hollow head breather bolts makes the crankcase pressure rise higher (or lower) in the process of expelling the gas. ((aswracing of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-era-specific-and-model-specific/​frame-mount-evo-sportster-talk-1986-2003-models/​138864-why-do-screamin-eagle-breathers-have-pin-hole-ends?​highlight=breather+bolts#​post2960323)) \\
- +
-== 91-03 ==+
  
 +== 1991-2003 ==
 91-03 breather bolts. \\ Outside threads are 1/2" x 13 (hole through the middle is 5/6" nominal). \\ 91-03 breather bolts. \\ Outside threads are 1/2" x 13 (hole through the middle is 5/6" nominal). \\
 {{:​techtalk:​evo:​carb:​91-03_breather_bolts_1_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack)) {{:​techtalk:​evo:​carb:​91-03_breather_bolts_2_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack)) {{:​techtalk:​evo:​carb:​91-03_breather_bolts_1_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack)) {{:​techtalk:​evo:​carb:​91-03_breather_bolts_2_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack))
  
-== 04 and Up == +== 2004 and Up ==
 Crankcase pressure was increased in 2004 by several means. \\ Crankcase pressure was increased in 2004 by several means. \\
 One of which was the reduction of the hole size in the breather bolts on the engine side (more restriction). \\ One of which was the reduction of the hole size in the breather bolts on the engine side (more restriction). \\
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 They also allow the air to leave the vents at a faster rate. \\  They also allow the air to leave the vents at a faster rate. \\ 
  
-04+ breather bolts. \\ Outside threads are 1/2" x 13 (2 different sizes thru the middle - nominally 1/16" (1.5875 mm) in the rear and 5/16" in the front). ((tomcat of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2073932&​page=19)) ((Folkie of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2073932&​page=22)) ((http://​xlforum.net/​forums/showthread.php?​p=5756327#post5756327)) \\  +04+ breather bolts. \\ Outside threads are 1/2" x 13 (2 different sizes thru the middle - nominally 1/16" (1.5875 mm) in the rear and 5/16" in the front). ((tomcat 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/​page19?​t=2073932&​page=19)) ((Folkie 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/​page22?​t=2073932&​page=22)) ((https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​28874-stock-air-cleaner-box-modifications/​page20#post4310316)) \\  
-{{:​techtalk:​evo:​engmech:​04_up_breather_bolt_3_by_folkie.jpg?​direct&​300|}} ((photo by Folkie of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5756327#post5756327)) {{:​techtalk:​evo:​engmech:​04_up_breather_bolt_2_by_folkie.jpg?​direct&​300|}} ((photo by Folkie of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5756327#post5756327))  {{:​techtalk:​evo:​engmech:​04_up_breather_bolt_1_by_folkie.jpg?​direct&​300|}} ((photo by Folkie of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​p=5756327#post5756327)) +{{:​techtalk:​evo:​engmech:​04_up_breather_bolt_3_by_folkie.jpg?​direct&​300|}} ((photo by Folkie of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​28874-stock-air-cleaner-box-modifications/​page20#post4310316)) {{:​techtalk:​evo:​engmech:​04_up_breather_bolt_2_by_folkie.jpg?​direct&​300|}} ((photo by Folkie of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​28874-stock-air-cleaner-box-modifications/​page20#post4310316))  {{:​techtalk:​evo:​engmech:​04_up_breather_bolt_1_by_folkie.jpg?​direct&​300|}} ((photo by Folkie of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​28874-stock-air-cleaner-box-modifications/​page20#post4310316)) 
  
-If you know someone with a lathe, you can have some stainless steel breather bolts made. ((photos by Folkie of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=2073497&​highlight=oil+level&​page=7)) \\+If you know someone with a lathe, you can have some stainless steel breather bolts made. ((photos by Folkie of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-general-discussion-and-problems/​196939-oil-in-air-cleaner/​page7?​t=2073497&​highlight=oil+level&​page=7)) \\
 {{:​techtalk:​evo:​engmech:​stainless-steel-breather-bolts-1_by_folkie.jpg?​direct&​300|}} {{:​techtalk:​evo:​engmech:​stainless-steel-breather-bolts-2_by_folkie.jpg?​direct&​300|}} {{:​techtalk:​evo:​engmech:​stainless-steel-breather-bolts-1_by_folkie.jpg?​direct&​300|}} {{:​techtalk:​evo:​engmech:​stainless-steel-breather-bolts-2_by_folkie.jpg?​direct&​300|}}
  
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 Or it contributes to too high of oil density and slings excess oil out. \\ Or it contributes to too high of oil density and slings excess oil out. \\
 Other factors are involved so results will vary. \\ Other factors are involved so results will vary. \\
 +
 +====== Breather Valve Testing ======
 +[[techtalk:​ref:​engmech04#​crankcase_pressure_testing|Click Here]] for information on testing crankcase pressure in the Sportsterpedia. \\
 +
 +There are no service intervals for the breather valve(s) in the FSMs. Also, there is no method of testing them in the FSMs. \\
 +But when they harden over time, you might experience more oil vapor, oil droplets or oil puking out the breather vent(s). \\
 +
 +The air coming out the vent(s) pulses according to piston position. \\
 +On upstroke, a low pressure is created in the bottom end. On downstroke, positive air pressure is created by piston downstroke. \\
 +
 +It's never a bad idea to replace the breather valves if you have any question whether you have a bad one. \\
 +From the pics, it looks like the front breather unit is stopped up.
 +1986-1990 Sportsters have one umbrella in the breather baffle tube inside the cam cover. \\
 +1991-2003 Sportsters have (2) umbrellas (one in each rocker box). \\
 +2004-up Sportsters have (2) umbrellas (one in each rocker box inside a sealed plastic breather unit). \\
 +The 2004 breather units have a removable fiber mesh filter under the umbrella that can stop up with gunked oil. \\
 +The mesh disc in the unit can get oil soaked and not pass any air through the umbrella. \\
 +The oil on the soaked mesh can vapor off if it doesn'​t cool on shutdown and gunk up there. If it gunks up, the mesh should be pulled and cleaned or replaced. \\
 +
 +===== Test for air flow at the vent =====
 +You can verify a stopped up breather valve by "​feeling"​ for air moving from the breather vent(s) with the air cleaner off, finger near each vent. \\
 +As long as you have know air is moving, then the breather valve isn't stopped up. \\
 +That doesn'​t mean it's working properly though. \\
 +It's hard to tell by feel alone if air is moving out or if air is moving in. \\
 +But there is a point where you may FEEL both air out and air in at the fingertip near the vent(s). \\
 +If there are any questions about the umbrella valves / units working properly, you could just replace them and be done with it. \\
 +With the rubber umbrellas hardening over time, there is nothing lost by replacing them. \\
 +
 +However, with the air cleaner off and a finger placed into the vent air stream; \\
 +
 +  * The exiting air from the vent is being sped up from the umbrella chamber to the vent. \\ This will pressurize the exit vent, hence the "​FEEL"​ of pressure. ((bustert of the XLFORUM https://​www.xlforum.net/​forum/​sportster-motorcycle-forum/​sportster-motorcycle-general-discussion-and-problems/​203992-only-one-breather-bolt-breathing?​t=2081302)) \\ When the flow stops abruptly (pulse finishes), there is an instant void that is filled with atmospheric pressure. \\ Hence the "​FEEL"​ of return flow.
 +  * A new flexible umbrella is designed to allow pressure to move out, not in. \\ However, outside air can still enter through the oil drain back hole on engine vacuum cycles.
 +  * 1986-up breather valves also incorporate an oil drain back hole for engine vacuum to pull separated oil from mist back into the motor. \\ The drain hole is past the umbrella between it and the outlet air vent. The drain hole is not controlled by the umbrella but rather engine vacuum. \\ So after the drain hole empties separated oil and is still under vacuum at that split second, holding a finger to the vent may feel a slight vacuum.
 +  * If an umbrella is stiff and not closing fully, you may FEEL air both push and pull at the breather vent. \\ The umbrella has a loose clearance under it. \\ It has a stem that pops into a hole in it's resting place and the stem is slightly longer than the hole is deep. \\ If an umbrella hardens, it will do so after cooling down, engine shut off. \\ So it will harden in it's flat position. \\ On startup, positive air pressure (and oil mist) will still get under and by the affected umbrella, just not as well as if it were flexible. \\ So at it's vent, you may feel less air pressure due to a partially opening breather valve.
 +  * The faster RPM, the faster the breather "​umbrella"​ acts (flexing closed on upstroke and open on downstroke). \\ If the rubber umbrella hardens over time, it may not be able to act as fast as the pistons. \\ So you may "​feel"​ both pressure and vacuum at the vent with your finger tip, air cleaner removed.
 +
 +{{:​techtalk:​evo:​engmech:​2004-up_breather_vent_-_feeling_air_movement_by_hippysmack.png?​direct&​500|}} ((drawing by Hippysmack)) \\
 +
 +There is an overlap on the bottom stroke cycle where the rear piston is at the bottom of it's stroke and the front piston is still coming down. \\
 +Next, the rear piston rises creating a partial lowering of air pressure under the front piston. \\
 +Full vacuum is not created until both pistons are on their up stroke. \\
 +So there is a lull area in each cycle that can be perceived as both pressure and suction at the breather vent even with good working umbrellas. \\
 +
 +{{:​techtalk:​evo:​engmech:​2004-up_breather_vent_-_how_air_vacuum_closes_it_by_hippysmack.png?​direct&​500|}} ((drawing by Hippysmack)) \\
 +
 +===== Blow testing through the vent =====
 +Since it's a one-way valve, air should go out but not come back in (past the umbrella itself). \\
 +
 +Before you position the hose, you can use a bit of clean pipe and blow gently through the breather. ((Four Speed of the XLFORUM https://​www.xlforum.net/​forum/​sportster-motorcycle-forum/​sportster-motorcycle-era-specific-and-model-specific/​frame-mount-evo-sportster-talk-1986-2003-models/​196577-1987-883-breather-bolts-are-different#​post4295094)) \\
 +It should close the valve and stop air flow (if you use a quick hard breath). \\
 +However, blowing slow and gently will allow a small amount of breath to go into the engine through the tiny oil drainback hole. \\ 
 +You may have to find an aftermarket replacement if the valve is shot and OEM replacements are hard to come by. \\
 +The 5 speed (rocker box) umbrellas are smaller than the 4 speed (cam cover) umbrellas and these won't interchange. \\
 +
  
 \\ \\