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techtalk:evo:engmech07 [2019/11/14 04:01]
hippysmack [2004-Present Engine Breathing]
techtalk:evo:engmech07 [2019/11/14 04:35]
hippysmack [Crankcase Ventilation]
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 91 and up engines vent through a valve in each rocker box and out the hollow breather bolts in each head. \\ 91 and up engines vent through a valve in each rocker box and out the hollow breather bolts in each head. \\
  
-{{:​techtalk:​evo:​engmech:​86-90_cc_pressure_drawing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) {{:​techtalk:​evo:​engmech:​86-90_engine_crankcase_breathing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack))+{{:​techtalk:​evo:​engmech:​a86-90_cc_pressure_drawing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) {{:​techtalk:​evo:​engmech:​a86-90_engine_crankcase_breathing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack))
  
-{{:​techtalk:​evo:​engmech:​91_and_up_cc_pressure_drawing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) {{:​techtalk:​evo:​engmech:​91-up_engine_crankcase_breathing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack))+{{:​techtalk:​evo:​engmech:​a91_and_up_cc_pressure_drawing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) {{:​techtalk:​evo:​engmech:​a91-up_engine_crankcase_breathing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack))
  
 ====== Late 1984-1990 Engine Breathing ====== ====== Late 1984-1990 Engine Breathing ======
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         * Air pressure escapes the head through the hollow bolts (one in each head) that hold the air cleaner mount.         * Air pressure escapes the head through the hollow bolts (one in each head) that hold the air cleaner mount.
  
-{{:​techtalk:​evo:​engmech:​a91-03_sportster_head_breathing_2_drawing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) {{:​techtalk:​evo:​oil:​crankcase_pressure_separation_chambe_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack))+{{:​techtalk:​evo:​engmech:​91-03_sportster_head_breathing_2_drawing_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) {{:​techtalk:​evo:​oil:​crankcase_pressure_separation_chambe_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack))
  
   * The Parts Catalog and FSM are a bit confusing regarding how many umbrellas are used and where. \\ The information is there but it's just not clear. \\ The parts catalog only shows an exploded diagram of one rocker box assembly on the Rocker Arms, Covers and Pushrods page. \\ Yet, the description shows that 2 umbrellas are required. \\ It's the same for all of the parts on that page as well as each newer parts catalog (1 pushrod, tube ,lifter and related parts). \\ This is the norm mostly throughout the subsequent catalogs with multiple (same) parts. \\ It's assumed this was done to save money on printing the catalogs (replicated information deleted). \\ The FSM displays the same exploded diagram as the parts catalog in the front of the Cylinder Head section. \\ It's only at the end of the Installation article does it say to install new gaskets on the middle rocker box (with the breather valve on the intake side). \\ There is no dedicated section on the rocker box or umbrella valves (which seem to be regarded as mere gaskets).   * The Parts Catalog and FSM are a bit confusing regarding how many umbrellas are used and where. \\ The information is there but it's just not clear. \\ The parts catalog only shows an exploded diagram of one rocker box assembly on the Rocker Arms, Covers and Pushrods page. \\ Yet, the description shows that 2 umbrellas are required. \\ It's the same for all of the parts on that page as well as each newer parts catalog (1 pushrod, tube ,lifter and related parts). \\ This is the norm mostly throughout the subsequent catalogs with multiple (same) parts. \\ It's assumed this was done to save money on printing the catalogs (replicated information deleted). \\ The FSM displays the same exploded diagram as the parts catalog in the front of the Cylinder Head section. \\ It's only at the end of the Installation article does it say to install new gaskets on the middle rocker box (with the breather valve on the intake side). \\ There is no dedicated section on the rocker box or umbrella valves (which seem to be regarded as mere gaskets).
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         * Air pressure escapes the head through the hollow bolts (one in each head) that hold the air cleaner mount.         * Air pressure escapes the head through the hollow bolts (one in each head) that hold the air cleaner mount.
  
-{{:​techtalk:​evo:​engmech:​a04_up_head_breathing_drawing_2_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack))+{{:​techtalk:​evo:​engmech:​04_up_head_breathing_drawing_2_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack))
  
 Just as with the 91-03 umbrella valves, only 1 breather valve per side is used. \\ Just as with the 91-03 umbrella valves, only 1 breather valve per side is used. \\