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techtalk:evo:engmech07 [2020/02/10 17:03] hippysmack [Sub Documents] |
techtalk:evo:engmech07 [2020/08/08 23:20] hippysmack [1991-2003 Engine Breathing] |
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| ====== 1991-2003 Engine Breathing ====== | ====== 1991-2003 Engine Breathing ====== | ||
| + | **An important note**: \\ | ||
| + | Factory engine breather valves on all Evo Sportsters are inside the engine. \\ | ||
| + | The lines / hoses that leave the engine and any apparatus to route the air to different places are part of the venting system. \\ | ||
| + | Many aftermarket manufacturers advertise that they are selling "Engine Breathers when they are actually only selling the vent line / tube assemblies. \\ | ||
| + | |||
| * 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 one-way umbrella valves (AKA Foo Foo 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)) | * The new breather system uses one-way umbrella valves (AKA Foo Foo 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)) | ||
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| == 91-03 == | == 91-03 == | ||
| - | 91-03 breather bolts. \\ | + | 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)) | ||
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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 (small hole is nominally 1/16" or 1.5875 mm). ((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 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)) \\ |
| {{: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 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)) | ||
