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techtalk:ih:engmech07 [2019/12/04 00:33] hippysmack [76< Timed Breather Valve] |
techtalk:ih:engmech07 [2020/09/17 04:06] hippysmack [Breather Valve Alternatives] |
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Documents from HD Racing from the period show no HP gain between the 2 systems when the breather is properly timed ( which didn't happen a lot). \\ | Documents from HD Racing from the period show no HP gain between the 2 systems when the breather is properly timed ( which didn't happen a lot). \\ | ||
===== 76< Timed Breather Valve ===== | ===== 76< Timed Breather Valve ===== | ||
- | The rotary breather valve is timed to open on the downstroke of the pistons. ((1960 HD FSM pg 3a-15)) \\ | + | ==== Sub Documents ==== |
+ | * [[techtalk:ih:engmech07a|Timing the 76< Breather Valve]] | ||
+ | |||
+ | 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 open 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. \\ | This allows crankcase exhaust air pressure to expel the scavenge oil from the crankcase breather oil trap into the gearcase. \\ | ||
- | The breather valve closes on piston upstroke, creating vacuum in the crankcase. \\ | + | 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. \\ | ||
+ | |||
+ | A street oil pump has 2 slots and is driven at 1/2 engine speed. ((thefrenchowl of the XLFORUM http://xlforum.net/forums/showthread.php?t=448751)) \\ | ||
+ | A racing oil pump has 4 slots and is driven at 1/4 engine speed. \\ | ||
+ | All 4 stroke engines takes two revolutions before you come back to the timing marks being all aligned. | ||
How the volume compares when the breather opens as to when it closes: ((Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1204854&page=3)) \\ | How the volume compares when the breather opens as to when it closes: ((Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1204854&page=3)) \\ | ||
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This diagram shows the volume swept by piston action in a 1000cc motor. \\ | This diagram shows the volume swept by piston action in a 1000cc motor. \\ | ||
It shows how much displacement is changed from min volume (0 cubic inches) to max volume(56.2 ci more than min). \\ | It shows how much displacement is changed from min volume (0 cubic inches) to max volume(56.2 ci more than min). \\ | ||
- | {{:techtalk:ih:engmech:breather_valve_drawing_1_by_dr_dick.jpg?direct&400|}} ((drawing by Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1204854&page=3)) \\ | + | {{:techtalk:ih:engmech:breather_valve_drawing_1_by_dr_dick.jpg?direct&800|}} ((drawing by Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1204854&page=3)) \\ |
There's only 1.2 cubic inches of net outward flow per revolution. \\ | There's only 1.2 cubic inches of net outward flow per revolution. \\ | ||
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There are other threads but this pretty much covers it all anyhow. Pretty simple but seems to cause repeated headaches for such a pesky little thing. ((Hopper from the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=wet+sumping)) | There are other threads but this pretty much covers it all anyhow. Pretty simple but seems to cause repeated headaches for such a pesky little thing. ((Hopper from the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=wet+sumping)) | ||
+ | |||
+ | ====== Oil Slinger ====== | ||
+ | |||
+ | Crankcase exhaust air escapes from the gearcase through the external breather tube. ((HD Sportster FSM pg 3A-15)) \\ | ||
+ | Any oil carried still carried by exhaust air is separated from the air by an oil slinger on the generator drive gear. \\ | ||
+ | |||
+ | |||
\\ | \\ |