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techtalk:ref:engmech04a [2019/11/14 06:09] – [Dissecting the Hayden KVP38 Crankcase Breather Valve] hippysmacktechtalk:ref:engmech04a [2024/01/14 21:47] (current) – hippysmack
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 The segments of the "Background" information in the patent material are shown in italics below. \\ The segments of the "Background" information in the patent material are shown in italics below. \\
-Comments on this information is shown in bold below. ((Hippysmack of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=39)) \\+Comments on this information is shown in bold below. ((Hippysmack 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/page39?t=2073932&page=39)) \\
  
-{{:techtalk:ref:engmech:1hayden_breather_valve_drawing_by_hippysmack.jpg?direct&300|}} ((drawing by Hippysmack))+{{:techtalk:ref:engmech:hayden_breather_valve_drawing_by_hippysmack.jpg?direct&300|}} ((drawing by Hippysmack))
  
 //A crankcase breather valve for ventilation and pressure control within the crankcase of an internal combustion engine in which pistons stroke upwardly and downwardly in a synchronous movement. The valve is inserted into a breather hose which conducts gases into and out of the crankcase. The valve comprises a resilient valve member, preferably an elastomeric umbrella-type seal, spaced above a seal seat and forming a gap there between through which gases may flow either direction during portions of the pistons' stroke cycle. The valve construction permits three operating modes: firstly to permit the egress of positive pressure gas out of the crankcase and through the gap while the pistons stroke downwardly; secondly, to permit the ingress of a small amount of gas back through the gap into the crankcase when the crankcase pressure changes from positive to negative; and thirdly to check further ingress of gas into the crankcase at greater crankcase suctions, developed when the piston's are moving upwardly.// //A crankcase breather valve for ventilation and pressure control within the crankcase of an internal combustion engine in which pistons stroke upwardly and downwardly in a synchronous movement. The valve is inserted into a breather hose which conducts gases into and out of the crankcase. The valve comprises a resilient valve member, preferably an elastomeric umbrella-type seal, spaced above a seal seat and forming a gap there between through which gases may flow either direction during portions of the pistons' stroke cycle. The valve construction permits three operating modes: firstly to permit the egress of positive pressure gas out of the crankcase and through the gap while the pistons stroke downwardly; secondly, to permit the ingress of a small amount of gas back through the gap into the crankcase when the crankcase pressure changes from positive to negative; and thirdly to check further ingress of gas into the crankcase at greater crankcase suctions, developed when the piston's are moving upwardly.//
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 **The gear driven breather's last year was 1978. \\ **The gear driven breather's last year was 1978. \\
-They left out the '79 style internal reed valve. \\ +They left out the '79 style internal reed valve and the fact that Sportsters lost the timed breather in '77. \\ 
-They are representing ironhead technology up to 1992. \\+They are representing ironhead technology up to 1992 (not true for Sportsters). \\
 They also cite excessive suction in the oil tank and lack of an oil head at the scavenge port in the sump as being sensitive to crankcase pressure. \\ They also cite excessive suction in the oil tank and lack of an oil head at the scavenge port in the sump as being sensitive to crankcase pressure. \\
 Some points of interest:** \\ Some points of interest:** \\
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   * **Vacuum in the air above is pulled from above, not below and the oil in the tank is much heavier than the air above.** \\   * **Vacuum in the air above is pulled from above, not below and the oil in the tank is much heavier than the air above.** \\
   * **Crankcase pressure cannot suck oil from the tank unless it's already been compromised by other means. \\ (worn or defective OEM breather valve)**   * **Crankcase pressure cannot suck oil from the tank unless it's already been compromised by other means. \\ (worn or defective OEM breather valve)**
-  * **The patent is suggesting that too much vacuum (negative pressure) can cavitate the oil pump.** +  * **The patent is suggesting that too much vacuum (negative pressure) can cavitate the oil pump.** \\ This is true. 
-  * **It also says the OEM umbrella is normally closed. But it isn't sealed and we do know they do let air back into the crankcase.**+  * **It also says the OEM umbrella is normally closed**. \\ But it isn't sealed all the time (transients) and we do know they do let a slight amount of air back into the crankcase. \\ This helps to equalize mean pressure somewhat.
   * **According to the patent information, the drain hole in the breather valve system has a dual purpose.**   * **According to the patent information, the drain hole in the breather valve system has a dual purpose.**
     - **It drains oil that gets past the umbrella.**     - **It drains oil that gets past the umbrella.**

Trace: • REF: Service Procedures 9H • REF: Electrical System • REF: Tools & Fasteners • REF: Engine Mechanicals - Sub-03F • REF: Engine Mechanicals - Sub-04A