Differences

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--- techtalk:evo:engmech07 [2019/08/12 03:31]
hippysmack [Head Breather Bolts]
+++ techtalk:evo:engmech07 [2019/08/18 02:36]
hippysmack [Head Breather Bolts]
@@ Line 105: / Line 105: @@
 |{{: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))  |||
 ====== 2004-Present Engine Breathing ======
@@ Line 140: / Line 141: @@
 |{{: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|}}|
-==== 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))\\
 The rocker box cover gasket is part of the seal for the breather port. \\
@@ Line 163: / Line 164: @@
 {{: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))
+====== Head Breather Bolts ======
+See also [[techtalk:ref:engmech04|Evo Crankcase Pressure and Engine Breathing]] in the REF section of the Sportsterpedia. \\
+Since 86-90 engines breath through the cam chest cover instead of the heads, the air cleaner bolts are solid (not hollowed). \\
+and up engines breath out the heads through hollowed out air cleaner mounting bolts (or breather bolts). \\
+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)) \\
+== 91-03 ==
+-03 breather bolts. \\
+{{: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 ==
+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). \\
+The smaller hole creates higher pressure in the crankcase on piston downstroke which aides in oil scavenging. \\
+They also allow the air to leave the vents at a faster rate. \\
++ 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)) \\
+{{: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))
+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)) \\
+{{: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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