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techtalk:ref:engmech04 [2019/07/12 21:20]
hippysmack [Oil Tank's Role vs Wetsumping]
techtalk:ref:engmech04 [2019/11/07 21:16] (current)
hippysmack [Sub Documents]
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 {{:​techtalk:​ref:​engmech:​86-90_sportster_positive_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) {{:​techtalk:​ref:​engmech:​86-90_sportster_negative_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) {{:​techtalk:​ref:​engmech:​86-90_sportster_positive_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) {{:​techtalk:​ref:​engmech:​86-90_sportster_negative_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack))
  
-91-03 models with head breather vents: \\ +91-97 models with head breather vents: \\ 
-{{:​techtalk:​ref:​engmech:​91-03_sportster_positive_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} ​((drawing by Hippysmack)) ​{{:​techtalk:​ref:​engmech:​91-03_sportster_negative_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} ​((drawing by Hippysmack))+{{:​techtalk:​ref:​engmech:​91-97_sportster_positive_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} {{:​techtalk:​ref:​engmech:​91-97_sportster_negative_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} \\ 
 + 
 +98-03 models with head breather vents: \\ 
 +{{:​techtalk:​ref:​engmech:​98-03_sportster_positive_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} {{:​techtalk:​ref:​engmech:​98-03_sportster_negative_crankcase_pressure_by_hippysmack.jpg?​direct&​300|}} ​\\
  
 04 and Up models with head breather vents: \\ 04 and Up models with head breather vents: \\
Line 206: Line 209:
 Blowby pertains to the condition of ring seal at the cylinders / pistons. \\ Blowby pertains to the condition of ring seal at the cylinders / pistons. \\
 Combustion above the piston is pushed past the rings and into the crankcase. \\ Combustion above the piston is pushed past the rings and into the crankcase. \\
 +It is fundamentally just exhaust that went past the rings instead of out the exhaust port. ((aswracing oftheXLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4)) \\
 +It's depleted of oxygen, it's hot, and it picks up moisture and oil in it's travels through the crankcase and into your intake tract. \\
 +So it's displacing oxygen in the intake charge (through the air cleaner) that would otherwise contribute to combustion. \\
 +It also heats the intake charge when the breather vent is piped back to the air cleaner which contributes to detonation. \\
 +It's just a bad thing all the way around, robbing power, causing detonation, and contributing to carbon build-up. \\
 +It's well worth it to remove it from the intake tract and vent it to the atmosphere or exhaust instead. \\
 +
 What actually 'blows by' the rings and into the crankcase is a mix of unburnt fuel, water, soot, acids etc. ((bunny32 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=67658&​page=2)) \\ What actually 'blows by' the rings and into the crankcase is a mix of unburnt fuel, water, soot, acids etc. ((bunny32 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=67658&​page=2)) \\
  
Line 293: Line 303:
 Listen for where the air is coming out during the test: intake port, exhaust port, or breathers. \\ Listen for where the air is coming out during the test: intake port, exhaust port, or breathers. \\
 See also [[techtalk:​ref:​svcproc21#​cylinder_leak-down_test|Performing a cylinder leak down test]] in the REF section of the Sportsterpedia. \\ See also [[techtalk:​ref:​svcproc21#​cylinder_leak-down_test|Performing a cylinder leak down test]] in the REF section of the Sportsterpedia. \\
 +
 +====== Crankcase Pressure Testing ======
 +===== Dyno testing using the timing plug location for an additional crankcase vent by aswracing =====
 +
 +The following is to share some dyno testing by aswracing of using the timing plug location for an additional crankcase vent. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4)) \\
 +
 +First, a little background. \\
 +In the stock configuration,​ the crankcase vents through a pair of "​umbrella"​ valves, which are essentially check valves. \\
 +There is a slight air inlet into the motor from a tiny hole near the umbrella. ((Hippysmack)) \\
 +It acts as both an oil drain for anything that gets past the umbrella and an air intake to keep negative pressure from getting too high. 
 +The pistons come down the first time and the crankcase air is expelled with the air being forced out through the umbrella valves. \\
 +
 +But when the pistons go back up, the umbrella valves block the inflow of air, causing a slight vacuum in the crankcase. \\
 +The next time the pistons come down, crankcase pressure will return to atmospheric at BDC before the upstroke. \\
 +If no air is allowed into the motor, the crankcase will cycle between a vacuum (pistons up) and atmospheric (pistons down). \\
 +
 +However, some air is actually allowed to enter, primarily in the form of blow-by that escapes the combustion chamber past the rings. \\
 +Therefore, in the stock design, there is a small net outflow. \\
 +The amount will vary with the condition of the motor.
 +
 +Properly functioning umbrella valves therefore serve the purpose of significantly reducing the breather capacity requirement while also minimizing crankcase pressure. \\
 +Excessive airflow & oil discharge through the breathers can be caused by malfunctioning umbrella valves that are allowing more air into the motor. \\
 +
 +For this test, an additional vent was added at the timing plug hole. \\
 +No check valve was installed on this vent. \\
 +Therefore, the crankcase is being allowed to pull in air as the pistons go up. \\
 +**This fundamentally changes the engine'​s venting design**. \\
 +
 +Some people feel that allowing the engine to both inhale and exhale in this manner reduces crankcase pressure. \\
 +Several people cite a "seat of the pants" improvement in performance. \\
 +The purpose of this test was to determine if there actually is a performance improvement from this change to the venting system. \\
 +
 +The fitting arrangement used is in the pic below. \\
 +The threads on the flare match the timing plug hole threads. \\ 
 +There are two fittings threaded together and app. two feet of 3/8" I.D. hose was attached to the hose barb.
 +
 +|3/8" flare to 1/4" FPT fitting \\ with a 1/4" MPT to 3/8" hose barb. ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|Fitting and hose as installed on the bike.((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|Test bike (near stock 1999 M2). ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|
 +|{{:​techtalk:​ref:​engmech:​timing_plug_adapter_by_aswracing.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​testing_cc_pressure_1_by_aswracing.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​testing_cc_pressure_2_by_aswracing.jpg?​direct&​300|}}|
 +
 +Lots and lots of dyno pulls were performed in each configuration and the configuration was switched back and forth a few times. \\
 +Dyno results are not 100% repeatable, and as such, below is a range of results for each configuration,​ as well as a comparison of best pulls. \\
 +Click on a chart to enlarge: \\
 +
 +|10 best pulls from the stock configuration. ((chart by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|10 best pulls from timing plug vent configuration. ((chart by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|Best stock pull and the best timing plug vent pull. ((chart by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|
 +|{{:​techtalk:​ref:​engmech:​dyno_and_breathing_1_by_aswracing.gif?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​dyno_and_breathing_2_by_aswracing.gif?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​dyno_and_breathing_3_by_aswracing.gif?​direct&​300|}}|
 +
 +As you can see, the difference is within the repeatability of the measurement. \\
 +If a person *had* to declare a winner, the results with the stock setup would seem to have a little edge. \\
 +(both in the "​best"​ results and just looking at the average of the 10 best results) \\
 +But I'd be careful doing that, you could be looking at normal variation. \\
 +
 +**Observations**:​ \\
 +I was surprised at how little air movement there was at the end of the hose. \\
 +When a motor is started with nothing screwed into the timing plug, there'​s a massive inhalation and exhalation evident. \\
 +But apparently, necking it down to a 3/8" hole and connecting 2 feet of hose adds a pretty significant restriction. \\
 +Air flow was nowhere near what I expected. \\
 +Unfortunately,​ getting a 7/16" or 1/2" hose into that area would be problematic,​ space is tight. \\
 +Plus, a fitting with the correct thread and a 7/16" or 1/2" hole may not be available. \\
 +
 +Another surprise was just how easy it was to plug the hose with my finger, and how it felt when I did. \\
 +The pressure was not great. \\
 +
 +===== Breather System Air Volume Test by DK Custom =====
 +The full article is on the DK Custom web site. [[http://​www.dkcustomproducts.com/​breather-system-flow-testing-results-video.htm]] \\
 +This testing was done to find out: \\
 +How much air was passed out the breather vents at idle, under a load, at cruising speeds and on throttle let-off. \\
 +And also the differences between a variety of HD engines, along with engines that had been hopped up with cams and or higher compression pistons/​heads. \\
 +
 +In this test, air was captured and measured as to how much water volume was displaced in a fixed period of time. \\
 +Taking the liquid ounce displacement,​ you can convert that to Cubic Feet Per Minute (CFM)
 +There are 957.50649350649 U.S. fluid oz. in 1 Cubic Foot. \\
 +
 +Results: \\
 +Sportsters move the least amount of air through the breathers.
 +Twin Cams move the most amount of air through the breathers, with little difference between air cooled and Twin Cooled. \\
 +Milwaukee-Eights move more air than Sportsters, but little more than half as much as the Twin Cams through the breathers. \\
 +Even more surprising is the least amount of air is moved on all bikes while at cruising RPM. \\
 +
 +The only way to get a significant amount of air to move through the Sportsters was to get the RPM up around redline. \\
 +(and that crankcase pressure was probably because the valves were beginning to float)
 +The most amount of air is moved through the breathers at idle, during hard acceleration and during deceleration. \\
 +A visual of this can be seen in this video: [[https://​www.youtube.com/​watch?​v=Kio4DEuOpCU|DK Custom Breather System Air Volume Testing of Harley-Davidsons ]] \\
 +
 +The actual numbers are in the chart below. \\
 +(engines warmed up / oil level on midway mark of dipstick before testing) \\
 +
 +|  **DK Customs Products Breather Report** (from different throttle / riding conditions) ​ |||||
 +|**Bike tested**|**CFM \\ (idle)**|**CFM \\ (cruise)**|**CFM \\ (hard acceleration)**|**CFM \\ (deceleration)**|
 +|**Air Cooled Twin Cam (103)**|.2172|.08|.1952|.2504|
 +|**Twin Cooled Twin Cam (103)**|.2548|.0972|.2231|.2874|
 +|**M8 Air Cooled (107)**|.1211|.06|.1059|.1127|
 +|**Sportster (1250 with high compression)**|.0125|.0125|.0125|.0125|
 +|:::|At redline (6200 RPM) with no load (.3326 CFM)||||
 +|**Sportster (1200)**|.0626|.0626|.0626|.0626|
 +
 +**CFM**: Cubic Feet per Minute. \\
 +**Deceleration Test**: Measured by chopping the throttle to 0% with the clutch in. \\
 +**Cruise** (low load test): Typical RPM most riding takes place in (2500-3000 RPM). \\
 +
 +===== Testing with a Slack Tube by bustert =====
 +==== Sub Documents ====
 +  * [[techtalk:​ref:​engmech04e|Building Your Own Slack Tube]]
 +  * [[techtalk:​ref:​engmech04f|Using / Diagnosing with a Manometer Slack Tube]]
 +  * [[techtalk:​ref:​engmech04g|Slack tube testing on a 1998 1250S model]]
 +
 +Testing was done from the timing plug hole and then from the oil tank with a slack tube on a 2001 XL1200S (with no load) by bustert of the XLFORUM. ((http://​xlforum.net/​forums/​showthread.php?​p=5767694#​post5767694)) \\
 +
 +On the left (from timing hole plug), the engine begins at high vacuum (green liquid line on scales in pics below). \\
 +Notice that there is a transition to a positive pressure above the 5k mark. \\
 +On the right (from oil tank), there is an equalization on positive and negative at 5K. \\
 +
 +One could speculate anything from over-running vent capacity to time factors. \\
 +The numbers are subjective to ambient temps and elevation. \\
 +However, we could use it as a tool to determine engine wear like they do on a diesel engine. \\
 +All-in-all, the subject engine operated as HD intended (within the intended most used rpm range). \\
 +
 +The results are in (inches of water) and you can convert to psig but remember, you have to add both sides. \\
 +So a 15 on one side with a 15 on the other would be 30". \\
 +
 +|Slack Tube testing from timing hole plug. ((photos by bustert of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5767694#​post5767694))||Slack Tube testing from oil tank||
 +|1000 \\ RPM|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_timing_hole_plug_1_by_bustert.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_oil_tank_1.1_by_bustert.jpg?​direct&​300|}}|1000 \\ RPM|
 +|2000 \\ RPM|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_timing_hole_plug_2_by_bustert.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_oil_tank_2_by_bustert.jpg?​direct&​300|}}|2000 \\ RPM|
 +|3000 \\ RPM|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_timing_hole_plug_3_by_bustert.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_oil_tank_3_by_bustert.jpg?​direct&​300|}}|3000 \\ RPM|
 +|4000 \\ RPM|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_timing_hole_plug_4_by_bustert.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_oil_tank_4.2_by_bustert.jpg?​direct&​300|}}|4000 \\ RPM|
 +|5000 \\ RPM|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_timing_hole_plug_5_by_bustert.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_oil_tank_5_by_bustert.jpg?​direct&​300|}}|5000 \\ RPM|
 +|6000 \\ RPM|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_timing_hole_plug_6_by_bustert.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​checking_cc_pressure_at_oil_tank_6_by_bustert.jpg?​direct&​300|}}|6000 \\ RPM|
 +
 +
 +The testing showed that the test bike acted as intended with head breathers (venting through lines bypassing the A/C to atmosphere). \\
 +
 +===== Testing Notes =====
 +Each of the tests above do basically support each other given the different variables. \\
 +But the results have to be taken in context as each have different criteria for testing. \\
 +
 +  * **Testing from DK Custom**:
 +    * The criteria for their testing was to see how much air was passed out the breather vents (outside the engine) at idle, under a load, at cruising speeds and on throttle let-off'​ for different model engines. They sell modified breather venting configurations and was doing some R&D presumably in the interest of same.
 +    * Their testing supports bustert'​s slack tube testing as normally at most of the RPM range, there is more vacuum than positive pressure. And it's the positive pressure that leaves the engine. Therefore, their results for the Sportster are equaled out more. Even though there is normal blowby throughout the RPM range, the vacuum created buffers that.
 +    * In example, 15" of vacuum at idle that all of a sudden is hit by 5" of positive pressure rolling the throttle still yields 10" of vacuum at the time. So there would be no air moving into the balloon or container at that point. In theory and during that transition from 15" to 10" vacuum, more oil is pushed toward the scavenge hole in the sump, the pump gets a fatter supply of oil to send to the tank, pressure goes up in the air space in the tank due to the restriction size of the vent.
 +
 +  * **Testing from bustert**:
 +    * This was a test of the differential pressure changes (inside the engine) through the RPM range up to 6000 RPM.
 +    * You may have read and heard from many sources that the Sportster requires a '​slight vacuum'​. But the slack tube testing puts a visual to the process showing that the '​slight vacuum'​ is not really a stagnant number but a constantly moving range.
 +
 +  * **Testing from aswracing**:​
 +    * Dyno testing was with the normal head breather vents in place (with and without the timing hole plug removed) to see if either would show increased HP over the other. \\ The dyno sheets show the affects (HP changes) between the stock setup and with addition of air induced into the engine through the RPM range. \\ However, it does not show internal pressures during the testing.
 +    * The testing revealed a dip in performance starting around 5700 RPM which coincides with bustert'​s slack tube testing showing positive and negative pressure equaling out up in that range. But the Dyno test is a load test as where the slack tube was done with no load on the engine... more variables.
 +
 +**What does all this mean**? \\
 +
 +The testing shows that there is more potential for crankcase pressure problems in the high RPM range. \\
 +It also shows that Sportster engine breathing was designed for peaks in the upper range but not for sustained use there. \\
 +There will be a normal amount of air passing the rings by design. \\
 +As the rings heat up and expand, there will be less air passed by them until you run up into the 5000 RPM range. ​ \\
 +Then, the rings will flutter and pass more combustion air into the crankcase which creates more positive pressure in the crankcase. \\
 +Normal blowby increases with engine speed. \\
 +Couple that with the increasing speed of the pistons which helps to equalize positive and negative pressure during operation. \\
 +As engine speed increases, there is not as much time to build vacuum on upstroke or positive pressure on downstroke due to the faster changing piston positions. \\
 +Just as you can inhale air slowly and fill up your lungs but faster breathing will not allow you to fill them due to the faster time that you exhale. \\
 +This would make for a shorter range of (both vacuum and positive) pressure that would be able to build in the crankcase. \\
 +So the internal pressure is more stable until extra air (blowby from ring flutter or other) is induced into the crankcase. \\
 +
 +**What causes extra air in the crankcase**?​ \\
 +
 +Ring flutter around 5000 RPM and higher is thought of as the main culprit on a healthy engine. \\
 +Gasket / air leaks react the same as ring flutter but at a lower RPM. \\
 +They allow more air into the engine that add to the positive and take away some of the negative (vacuum). \\
 +So the introduction of air leaks into the crankcase lowers the RPM at which pressure changes affect the system. \\  ​
 +Worn / stiff breather valves that do not fully close will allow more air at atmosphere into the crankcase. \\
 +This lowers the vacuum and contributes to higher positive pressure on downstroke changing the ratio at a lower RPM. \\
 +The timing of the breather valve opening and closing can also bring in air to the crankcase during upstroke. \\
 +Guess we could call that umbrella flutter. \\
 +The faster it closes, the more vacuum is kept in the crankcase on upstroke. \\
 +The slower it closes, the more air is allowed to enter and lower residual vacuum. \\
 +
 +**Why is the ratio of positive and negative pressure important**?​ \\
 +
 +It takes a balance of the two to run a Sportster engine. \\
 +
 +Piston upstroke creates negative pressure and suction of oil from the sump. \\
 +It pulls oil up in the form of oil mist to be tossed around on the moving metal parts. \\
 +So it is important for lubrication and it keeps down aeration in the oil. \\
 +But without the reciprocating piston downstroke, there wouldn'​t be a lot of force to help splash it around other than the spinning wheels. \\
 +The upstroke pulls oil into suspension (air/oil mist) so the downstroke can help blow the mist around working in conjunction with flywheel and cam rotation. \\
 +Negative pressure is also important for ring seal as it allows the rings to fully seat on the bottom of the ringlands during upstroke decreasing blowby. \\
 +Too much negative pressure is detrimental to oil scavenging as it allows more oil to be pulled up into suspension instead of moving toward the scavenge port in the sump. \\
 +The bulk of gravity oil on the sump floor is heavier than the moving air. \\
 +But the spinning action of the flywheels can pull that oil up to be slung around the wheels creating more drag as it does. \\
 +So it's important to get the excess oil in the bottom out of the engine as fast as possible to keep down flywheel drag. \\
 +That's where the positive pressure comes in. \\
 +
 +Positive pressure is important for oil scavenging as it works in conjunction with splash lubrication as well as the suction of the oil pump. \\
 +The positive pressure generated by the downstroke pushes oil toward the scavenge pump to be sucked vertically into the oil passage to the pump. \\
 +So there is a balance of positive and negative pressure that has to be maintained for overall engine operation. \\
 +
 +The role of positive and negative pressure can be confusing. \\
 +Even though there is a positive '​push'​ on internal pressure through piston downstroke, the overall internal pressure is still negative. \\
 +It's just less negative than it was before the downstroke. This creates a pulsing effect on oil in the sump which helps shift the oil toward the scavenge port. \\
 +Even though there is normal blowby throughout the RPM range, the vacuum created buffers that. \\
 +
  
 ====== Engine Breathing ====== ====== Engine Breathing ======
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 |{{:​techtalk:​ref:​engmech:​86-90_sportster_engine_breathing_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​91_sportster_engine_breathing_by_hippysmack.jpg?​direct&​300|}}| |{{:​techtalk:​ref:​engmech:​86-90_sportster_engine_breathing_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​91_sportster_engine_breathing_by_hippysmack.jpg?​direct&​300|}}|
  
-|  92-03 engine breathing paths. ((drawing by Hippysmack)) ​ |  04 and Up engine breathing paths. ((drawing by Hippysmack)) ​ | +|  92-97 engine breathing paths. ((drawing by Hippysmack)) ​ |  98-03 engine breathing paths. ((drawing by Hippysmack)) ​ |  04 and up engine breathing paths. ((drawing by Hippysmack)) ​ | 
-|{{:techtalk:​ref:​engmech:​92-03_sportster_engine_breathing_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​04_and_up_sportster_engine_breathing_by_hippysmack.jpg?​direct&​300|}}| +|{{techtalk:​ref:​engmech:​92-97_sportster_engine_breathing_by_hippysmack.jpg?​direct&​300|}}|{{techtalk:ref:​engmech:​98-03_sportster_engine_breathing_by_hippysmack.jpg?​direct&​300|}}|{{techtalk:​ref:​engmech:​04_and_up_sportster_engine_breathing_by_hippysmack.jpg?​direct&​300|}}|
  
 |  Testing CC pressure on the dyno. ((photo by Jörgen http://​xlforum.net/​forums/​showthread.php?​t=75740&​page=9)) ​ | |  Testing CC pressure on the dyno. ((photo by Jörgen http://​xlforum.net/​forums/​showthread.php?​t=75740&​page=9)) ​ |
Line 350: Line 558:
 In the right application they can not be beat but you better have your ducks in a row. \\ In the right application they can not be beat but you better have your ducks in a row. \\
  
 +**Buell crankcase breathing**:​ \\ 
 +|  This is a Buell XBRR with reed valves through the cam chest wall. ((photos by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=829935)) ​ || 
 +|{{:​techtalk:​ref:​engmech:​reed_valves_1_on_buell_xbrr_by_aswracing.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​reed_valves_2_on_buell_xbrr_by_aswracing.jpg?​direct&​300|}}|
  
  
Line 371: Line 581:
     * Bad ring seal helps evacuate the sump from oil. ((Jorgen of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=75740&​highlight=reed+valve&​page=7)) \\ But on the other hand it increases the flow rate through the crank vent system to such levels that a lot of oil droplets join in.     * Bad ring seal helps evacuate the sump from oil. ((Jorgen of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=75740&​highlight=reed+valve&​page=7)) \\ But on the other hand it increases the flow rate through the crank vent system to such levels that a lot of oil droplets join in.
  
-Reasons ​for oil puking out the engine breather:+Helpers ​for oil puking out the engine breather:
   - Wet Sumping:   - Wet Sumping:
     * During engine down time.     * During engine down time.
Line 408: Line 618:
 So to keep oil out of the A/C, means keeping engine breathing And wet sumping in balance. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5757523#​post5757523)) \\ So to keep oil out of the A/C, means keeping engine breathing And wet sumping in balance. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5757523#​post5757523)) \\
  
 +===== Breather Catch Can Test For Oil Leaks Out the Vent  =====
 +A test was done by XLFORUM member cjburr. Test apparatus and results are below. ((cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=13)) \\
 +This testing was done to help diagnose an oil leak that couldn'​t be seen or otherwise detected. \\
 +However, this may be a good exercise if you are concerned about how much oil you may be losing from the crankcase puking. \\
 +It should show what, how much and when oil accumulates in the hose / catch can. \\
 +The length / size of tubing will change crankcase pressure to an extent so the results may not reflect exactly what's going on inside your engine. \\
 +
 +The vent to air cleaner was inspected and then removed for testing. The factory system routes the breathers to the front of the carb. \\
 +There was no evidence of the amount of oil that was being lost in the intake tract. \\
 +With the Forcewinder A/C removed, there was no evidence of oil.
 +A homemade catch can with a vent hole and a clear tube was installed to inspect while riding. \\
 +
 +|  A/C removed. ((photo by cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=13)) ​ ||  Homemade catch can. ((photo by cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=13)) ​ |
 +|{{:​techtalk:​ref:​engmech:​breather_catch_can_test_1_by_cjburr.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​breather_catch_can_test_2_by_cjburr.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​breather_catch_can_test_3_by_cjburr.jpg?​direct&​300|}}|
 +
 +The A/C was re-installed with the venting ran to the catch can. \\
 +The oil tank was filled to just under half way up the stick with SYN3. \\
 +The bike was ridden hard (10 miles of city driving then 50 miles of elevated speeds). \\
 +RPM was ran up to 6000 in 5th (8 times) and up to 100 MPH for 2 miles twice. \\
 +Total miles run were 75 and all but 20 miles of that were at 80 MPH or more. \\
 +The only thing that showed up in the tube running to the catch can was just some moisture but no oil. \\
 +|  The catch can was clean but 1/4 quart of oil had been lost as viewed from the dipstick. ((photo by cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=13)) ​ |||
 +|{{:​techtalk:​ref:​engmech:​breather_catch_can_test_4_by_cjburr.jpg?​direct&​300|}}| {{:​techtalk:​ref:​engmech:​breather_catch_can_test_5_by_cjburr.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​breather_catch_can_test_6_by_cjburr.jpg?​direct&​200|}}|
  
  
Line 445: Line 678:
  
 **Late 1982-Early 1984 models**: \\ **Late 1982-Early 1984 models**: \\
- The internal crankcase breather valve was redesigned to incorporate a rubber umbrella valve attached to the base plate along with a larger diameter (1-3/4” O.D.) oil separator washer on the generator armature. ((HD Service Bulletin #M-848 dated April 9, 1982))+The internal crankcase breather valve was redesigned to incorporate a rubber umbrella valve. \\ 
 +This is attached to the base plate along with a larger diameter (1-3/4” O.D.) oil separator washer on the generator armature. ((HD Service Bulletin #M-848 dated April 9, 1982)) ​\\
  
 **Late 1984-1990 models**: \\ **Late 1984-1990 models**: \\
Line 492: Line 726:
 ** 2004-Present**:​ \\ ** 2004-Present**:​ \\
 In 2004 the MoCo made some changes to the umbrella valve configuration. \\  In 2004 the MoCo made some changes to the umbrella valve configuration. \\ 
-The umbrella was retained but now inside a plastic housing with a pre-umbrella oil separating screen. \\+The umbrella was retained but now inside a plastic housing with a pre-umbrella oil separating screen ​(fiber mesh). \\ 
 +On 03< models, the oil is actually separated by the umbrella. The umbrella doubles as a one way air valve. \\ 
 +On 04> models, the oil is separated first by the mesh below the umbrella which frees the umbrella to be more of a one way air valve. \\ 
 +There is an extra oil chamber between the in and out of the breather assembly. \\ 
 +So it could be said that the 04-up breather valve has 2 stage separation with a small hole in the middle chamber to drain what gets past the mesh. \\ 
 Each '​breather valve' is assembled into a plastic fitting that is sealed over the outlet hole in the lower rocker box to the head breather bolt. \\ Each '​breather valve' is assembled into a plastic fitting that is sealed over the outlet hole in the lower rocker box to the head breather bolt. \\
 The new breather valves were also accompanied with new style hollow air cleaner mounting bolts for the pressure to escape. \\ The new breather valves were also accompanied with new style hollow air cleaner mounting bolts for the pressure to escape. \\
 The new bolts are the same thread size as previous. \\  The new bolts are the same thread size as previous. \\ 
 But instead of a simple hex, it also has a shoulder past the hex for an O-ring to be fitted between the hex head and the air cleaner. \\ But instead of a simple hex, it also has a shoulder past the hex for an O-ring to be fitted between the hex head and the air cleaner. \\
-The breathing system is functionally the same as 91-03 with the one-way umbrella valves in the rocker boxes. \\ These exit crankcase vapors through vents in the top of the cylinder head and into the carb mouth to be burnt. ((FoxsterUK of the XLFORUM ​ http://​xlforum.net/​forums/​showthread.php?​t=518948&​highlight=wet+sumping))+The breathing system is functionally the same as 91-03 with the one-way umbrella valves in the rocker boxes. \\ These exit crankcase vapors through vents in the top of the cylinder head and into the carb mouth to be burnt. ((FoxsterUK of the XLFORUM ​ http://​xlforum.net/​forums/​showthread.php?​t=518948&​highlight=wet+sumping)) ​\\
 On each piston downstroke, crankcase pressure (air and oil mist) is routed up the pushrod tubes into the rocker box. \\ On each piston downstroke, crankcase pressure (air and oil mist) is routed up the pushrod tubes into the rocker box. \\
 Collected air pressure and oil mist in each rocker box is routed up into the breather valve unit in the lower portion of the box. \\ Collected air pressure and oil mist in each rocker box is routed up into the breather valve unit in the lower portion of the box. \\
 This mixture passes up from underneath the breather unit. \\ This mixture passes up from underneath the breather unit. \\
 The oil is designed to separate from the air by hitting the underside of the screen / umbrella valve and dropping back down into the rocker box. \\ The oil is designed to separate from the air by hitting the underside of the screen / umbrella valve and dropping back down into the rocker box. \\
 +
 From there it is routed back to the lower end. \\ From there it is routed back to the lower end. \\
 Air pressure is designed to continue up past the breather unit and exit a hole in each head on the intake valve side. \\ Air pressure is designed to continue up past the breather unit and exit a hole in each head on the intake valve side. \\
Line 520: Line 760:
 |  Breather Valves ((photo by DK Custom of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1582019&​page=11)) ​ |  View of one cut open. ((photos by Bored now of the XLFORUM, annotated by Hippysmack http://​xlforum.net/​forums/​showthread.php?​p=5761087#​post5761087)) ​ || |  Breather Valves ((photo by DK Custom of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1582019&​page=11)) ​ |  View of one cut open. ((photos by Bored now of the XLFORUM, annotated by Hippysmack http://​xlforum.net/​forums/​showthread.php?​p=5761087#​post5761087)) ​ ||
 |{{:​techtalk:​evo:​oil:​breather_valves_by_dk_custom.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​04_up_breather_1a_by_bored_now_annotated_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​04_up_breather_2a_by_bored_now_annotated_by_hippysmack.jpg?​direct&​300|}}| |{{:​techtalk:​evo:​oil:​breather_valves_by_dk_custom.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​04_up_breather_1a_by_bored_now_annotated_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​04_up_breather_2a_by_bored_now_annotated_by_hippysmack.jpg?​direct&​300|}}|
 +
 +|The mesh can become saturated with oil. ((photo by dieselvette of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2073932&​page=28))|Oil drain hole. ((photo by dieselvette of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2073932&​page=30))|Installed upright as shown. ((photo by dieselvette of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2073932&​page=30))|
 +|{{:​techtalk:​ref:​engmech:​04_up_breather_valve_1_by_dieselvette.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​04_up_breather_valve_2_by_dieselvette.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​04_up_breather_valve_3_by_dieselvette.jpg?​direct&​300|}}|
  
  
 ===== Aftermarket Breathers / PCV Valves ===== ===== Aftermarket Breathers / PCV Valves =====
 +==== Sub Documents ====
 +  * [[techtalk:​ref:​engmech04a|Dissecting the Hayden KVP38 Crankcase Breather Valve]] ​
 +
 There is a product called a Krankvent that can be plumbed into the lower, 6 o’clock position as an alternative to a stock foo-foo valve. ((Hopper of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=518948&​highlight=cam+chest+breather)) \\ There is a product called a Krankvent that can be plumbed into the lower, 6 o’clock position as an alternative to a stock foo-foo valve. ((Hopper of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=518948&​highlight=cam+chest+breather)) \\
 But they are not cheap. Automotive PCV valves are not really made to handle the revs or air volumes of a Harley. \\ But they are not cheap. Automotive PCV valves are not really made to handle the revs or air volumes of a Harley. \\
Line 558: Line 804:
     * Makes a clicking noise during operation.     * Makes a clicking noise during operation.
  
-|  Mercedes Benz P/N# 271-018-00-29 ((photo by electronbee of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=72099&​highlight=reed+valve&​page=10)) ​ |  Reed Valve ((photo by Bluto of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5761290#​post5761290)) ​ | +|  Mercedes Benz P/N# 271-018-00-29 ((photo by electronbee of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=72099&​highlight=reed+valve&​page=10)) ​ |  Reed Valve ((photo by Bluto of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5761290#​post5761290))  |  Doherty Power Vent ((Photo by goblin_dust of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=72099&​highlight=wet+sumping&​page=23))  | 
-|{{:​techtalk:​ref:​engmech:​mercedes_benz_pcv_valve_by_electronbee.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​reed_valve_by_bluto.jpg?​direct&​300|}}|+|{{:​techtalk:​ref:​engmech:​mercedes_benz_pcv_valve_by_electronbee.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​reed_valve_by_bluto.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​deimus_mod_2_by_goblin_dust.jpg?​direct&​300|}}|
  
 ==== Regarding horsepower gains from different breathers ==== ==== Regarding horsepower gains from different breathers ====
Line 584: Line 830:
 </​blockquote>​ </​blockquote>​
  
 +===== Head Vents vs Cam Chest Vent =====
 +CC pressure (while venting thru the heads) was [[techtalk:​ref:​engmech04#​head_vents_vs_cam_chest_vent|tested with a slack tube]] as in above. \\
 +Results of the testing showed that the test bike did perform as designed using breathers in the rocker boxes. \\
 +Sustained RPM on a street bike can be up in the 4000-5000 RPM range at highway speeds. \\
 +The test bike showed a positive charge forming in the crankcase around 5000 RPM. \\
 +This positive charge is responsible,​ in part, for oil puking out the vent(s) if the pressure gets too high. \\
 +So the farther past 5000 RPM, the more positive pressure is created. \\
  
-====Breather ​System Air Volume ​Testing ===== +{{:​techtalk:​ref:​engmech:​engine_breathing_thru_heads_vs_cam_chest_by_hippysmack.jpg?​direct&​300|}} ((drawing by Hippysmack)) 
- + 
 +==== 91-up Breather ​Bolts ==== 
 + 
 +The MoCo manipulated crankcase pressure with the different size holes in the breather bolts. \\ 
 +The crankcase splash holes were restricted in 2000 to keep more pressure in the crankcase. \\ 
 +Then the holes in the wall was closed up in 2004 to accommodate the addition of piston jets to cool the pistons. \\ 
 +The piston squirters (feed pressure from the pump) added the same amount of oil into the crankcase at a faster rate. \\ 
 +But the scavenger gerotors were not redesigned larger until 2007 to remove the oil faster from the crankcase. \\ 
 +So on 04-06 models, they got the same scavenge return rate (as previous models without the added oil). \\ 
 +The holes in the 04 Up bolts are stepped. They are smaller on the head side as above but bigger on the A/C side. \\ 
 +First, that creates more of a restriction than 91-03 models. The restriction can do a couple things: \\ 
 +It will create more backpressure inside the engine until a stronger force is applied from inside. \\ 
 +That stronger force would be the air created on downstroke. In a perfect world, the downstroke won't be impeded so the force won't slow down. \\ 
 +The higher positive pressure assists in oil scavenging (the pressure inside builds a little more from that restriction). ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2073932&​page=9)) \\ 
 +But it only bottles up pressure on downstroke and only to a point. That little more positive pressure is an extra push on the lower end toward the sump scavenge port. \\ 
 +Another result would be air moving out at a faster rate thru the smaller hole. The smaller hole creates higher pressure. Higher pressure equates to faster flow. \\ 
 + 
 +{{:​techtalk:​evo:​carb:​91-03_breather_bolts_1_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack)) {{:​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)) \\ 
 + 
 + 
 +==== Head Drainage ==== 
 +The debated question on head breathing systems is; \\ 
 +When the engine is running at high speed, is there any kind of pressure being created that might slow down the drainage from the top? ((NRHS Sales of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=31)) \\ 
 +The oil feed to the top end is pressurized and the return is gravity fed. ((jrclark19 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=31)) \\ 
 +The drain for the top end is at least 2-3 times larger than the hole in the pushrods. \\ 
 + 
 +It's been said that CC pressure moving up the pushrod tubes interferes with drain oil traveling down the tubes. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2073932&​page=2)) \\ 
 +However, drain oil mainly goes into the head / cylinder drain holes from the rocker arms spraying the valves. \\ 
 +And liquid oil is much heavier than air moving up the passage. \\ 
 +Separated oil from mist falls back into the tubes. But that oil is also pulled down on piston upstroke and air/mist once again goes up on piston downstroke. \\ 
 +The higher venting from the heads also gives any oil that may be being carried along with the gas time to "drop out". \\ 
 +(which returns the oil back to the cam chest vis the pushrod / lifter block drain holes via gravity) \\ 
 +Obviously, there is less time for oil to drop out of suspension while breathing out the cam chest instead. \\ 
 + 
 +The slack tube testing shows there is a predominate vacuum in a running engine until after 5000-6000 RPM. \\ 
 +Any output pressure in the head venting system has to travel up through separate pushrod tube passages to get out of the engine. \\ 
 +Any separated oil gravity falling from the rocker arms would overpower the positive upward push of crankcase pressure until the oil hit bottom. \\ 
 +An exception would be in high sustained, high RPM where there is excess ring flutter adding to equalized pressure in the crankcase. \\ 
 +(as in racing conditions). \\ 
 + 
 + 
 + 
 +==== Testing ​the Head Drains ==== 
 +Test performed by cjburr of the XLFORUM ((http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=31)) \\ 
 + 
 +//​Disclaimer:​ \\ 
 +For this to be more accurate, the oil flow rate of the engine when at high RPM would need to be evaluated. \\ 
 +This test was done with engine shut off. \\ 
 +However, the engine was able to get a quart of oil poured into it straight from the bottle with no problem with drainage. \\ 
 +The test can be made scientific with a little ingenuity. \\// 
 + 
 +This was a test to get an idea of the level the oil would need to get to in the heads to submerge the valve seals. \\ 
 +(before it went to the drain on the exhaust side and if it would pool up enough to submerge the exhaust side) \\ 
 +The head was installed on the bike with a jack under it so everything would be level. \\ 
 +Oil was poured into the head to watch it drain and see if the seal became submerged. \\ 
 + 
 +**Conclusion**:​ \\ 
 +The seals shouldn'​t become submerged from watching how fast the head drained. \\ 
 +However, there will be oil around the spring seats at all times. \\ 
 +To be 100% certain on this, the bike needs to be running but was beyond capabilities at the time of testing. \\ 
 +The springs and valves normally only receive splash oiling. \\ 
 +Oil was poured into the head from the bottle and monitored with very fast drainage in the ports. \\ 
 +CJ was 95% sure of his conclusion upon testing. \\ 
 +A whole quart of oil at room temperature flows slower that oil at operating temp. \\ 
 +That's pretty conclusive (at this level anyway). \\ 
 + 
 +Testing continued to see if perceived normal oil flow would flood the valve seals. \\ 
 +Oil was introduced into the head with a with a turkey baster. \\ 
 +(which is probably a higher volume of oil than it normally sees from the splash oiling) \\ 
 +However, if the drains were plugged, oil would overfill to the point of spewing oil at the seams and submerge the seals. ((cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=33)) \\  
 + 
 +|  Head ready for testing. ((photo by cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=31)) ​ |  Oil poured in and draining. ((photo by cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=31)) ​ |Oil level at the intake valve when it starts to drain to \\ the exhaust side. ((photo by cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=31)) ​ | 
 +|{{:​techtalk:​ref:​engmech:​head_drainage_test_1_by_cjburr.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​head_drainage_test_2_by_cjburr.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​head_drainage_test_3_by_cjburr.jpg?​direct&​300|}}| 
 + 
 +The oil you see in the first pic below is held there by the spring seat. \\ 
 +At no time did the level become so great as to submerge the exhaust valve seal. \\ 
 +You might be able to dress up the entrance to the exhaust drain with a burr to enhance flow to the drain. \\ 
 +But it may not be necessary as it does drain really well and the spring seat above it might negate any advantage you got from doing so. \\ 
 + 
 +|Oil level at the exhaust valve when draining stops. ((photo by cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=31)) ​ |   This is as high as the level got at the intake valve. ((photo by cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=31))  |  This is the drain in the exhaust pocket. ((photo by cjburr of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=53769&​highlight=valve+guide&​page=31))  |  
 +|{{:​techtalk:​ref:​engmech:​head_drainage_test_4_by_cjburr.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​head_drainage_test_5_by_cjburr.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​head_drainage_test_6_by_cjburr.jpg?​direct&​300|}}|
 ===== Engine Venting Mods ===== ===== Engine Venting Mods =====
-See also [[techtalk:​ref:​oil05|Engine and Primary Oil System Modifications]] for a listing of mods from the XLFORUM. \\+See also [[techtalk:​ref:​engmech05|Breather Venting / Relocation]] for a listing of breather ​mods from the XLFORUM. \\ 
 + 
 +In addition to the above, I also did a bunch of testing of the aftermarket breather check valves from Spyke and Hayden. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4)) \\ 
 +(and even did some experiments with vacuum pumps and the like) \\ 
 +Did some magazine articles here and there at the time. The motor was remarkably insensitive to anything I did with the breathers. \\ 
 +Like I said, the only thing I could get to show up on the Dyno sheet at all was the removing of the blow-by from the intake tract. \\
  
 Engine breathers control when CC pressure exits the engine. \\ Engine breathers control when CC pressure exits the engine. \\
Line 607: Line 945:
 The scavenge inlet sees pressure but is isolated from the vacuum when the pistons go back up. \\ The scavenge inlet sees pressure but is isolated from the vacuum when the pistons go back up. \\
 </​blockquote>​ </​blockquote>​
 +
 +
 ====== Wetsumping ====== ====== Wetsumping ======
 Click to read the full article on [[techtalk:​ref:​oil10#​wet_sumping|wetsumping]] in the REF section of the Sportsterpedia. \\ Click to read the full article on [[techtalk:​ref:​oil10#​wet_sumping|wetsumping]] in the REF section of the Sportsterpedia. \\
 +See also the Sportsterpedia page on [[http://​www.sportsterpedia.com/​doku.php/​techtalk:​ref:​oil05|Engine and Primary Oil System Modifications]] \\
  
 Wetsumping during shutdown periods is a condition of bad oil pump sealing, bad check valve or regulator (if equipped) sealing. \\ Wetsumping during shutdown periods is a condition of bad oil pump sealing, bad check valve or regulator (if equipped) sealing. \\
Line 720: Line 1061:
  
 77> engines deleted the timed open and closed breather valve as is in 76< motors. \\ 77> engines deleted the timed open and closed breather valve as is in 76< motors. \\
-The the camchest is always open to the flywheel cavity with a one way valve between the motor and the outside environment. \\+The camchest is always open to the flywheel cavity with a one way valve between the motor and the outside environment. \\
 The slang term "​FooFoo"​ comes from the annoying sound that it makes when it gets clogged up with oil residue. ((IronMick of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1332902&​page=3)) The slang term "​FooFoo"​ comes from the annoying sound that it makes when it gets clogged up with oil residue. ((IronMick of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1332902&​page=3))
  
Line 796: Line 1137:
 This practice is not just restricted to rubbermounts although due to the CC pressure change in 04, it is a more accepted practice. \\ This practice is not just restricted to rubbermounts although due to the CC pressure change in 04, it is a more accepted practice. \\
 The tank acts as an oil / air separator like the breather valve but the air only expels the engine from the engine breather vent. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1971026&​page=28)) \\ The tank acts as an oil / air separator like the breather valve but the air only expels the engine from the engine breather vent. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1971026&​page=28)) \\
 +
 +==== Lowering the oil level in the tank ====
  
 ** *When you lower the oil level in the tank, you are just masking the real problem* ** . \\ ** *When you lower the oil level in the tank, you are just masking the real problem* ** . \\
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     * The oil level only matters if the tank has been overfilled past the top mark on the dipstick. ((Toejam503 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5750657&​highlight=lower+oil+level#​post5750657))     * The oil level only matters if the tank has been overfilled past the top mark on the dipstick. ((Toejam503 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5750657&​highlight=lower+oil+level#​post5750657))
     * This is easy to do if you check the oil level and fill the tank BEFORE heating up the engine to operating temperature. \\ See more about [[techtalk:​ref:​oil01#​overfilling_the_oil_tank|Over filling the oil tank]] in the REF section of the Sportsterpedia.     * This is easy to do if you check the oil level and fill the tank BEFORE heating up the engine to operating temperature. \\ See more about [[techtalk:​ref:​oil01#​overfilling_the_oil_tank|Over filling the oil tank]] in the REF section of the Sportsterpedia.
 +    * Overfilling the oil tank can bring the level up over the vent to the crankcase. \\ This would stop up the vent to the cam chest, over-pressurize the tank and hinder scavenging from the sump. \\ Increased sump oil (not able to be scavenged fast enough) aides in oil suspension or air /oil density increasing crankcase pressure. \\ Increased crankcase pressure aides in oil puking out the vents.
   - **Running the oil level on the bottom dipstick line helps curb blowby. \\ Running the oil level at the middle to high side of the dipstick causes more blowby.** \\   - **Running the oil level on the bottom dipstick line helps curb blowby. \\ Running the oil level at the middle to high side of the dipstick causes more blowby.** \\
     * Running the oil level on the low mark of the stick effectually lowers the amount of oil that would collect in the sump.     * Running the oil level on the low mark of the stick effectually lowers the amount of oil that would collect in the sump.
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     * Lowering the amount of oil in the sump also leaves less oil there to get pulled up into suspension which thins out air / oil mist.     * Lowering the amount of oil in the sump also leaves less oil there to get pulled up into suspension which thins out air / oil mist.
     * It's the more dense air / oil mist that is the problem, not the oil level in the tank. \\     * It's the more dense air / oil mist that is the problem, not the oil level in the tank. \\
 +    * Many people say that it is important to leave plenty of empty space in your oil tank. ((Deimus of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=72099&​highlight=wet+sumping&​page=21)) \\
 +      * If you don't have excess crankcase pressure, you don't have to do that. You can fill the oil tank to the full mark on the dipstick without any issue.
 +      * The oil tank is a sealed space with a seal / O-ring on the dipstick. \\ The oil tank space is connected to the crankcase space via the vent hose that runs from the oil tank to the cam cover. \\ By filling the oil tank only half full, you create a larger air volume in the crankcase space itself. \\ This increased air volume can help buffer the pressure in an engine with only a slight problem with blow-by gasses combined with the restricted head vents.
 +      * However, if you either;
 +        * Restore your engine to like new low levels of blow-by.
 +        * Or if you improve the engine'​s ability to vent the pressure. \\ Then you don't need the extra buffer space provided by half filling your oil tank. \\ You can go ahead and fill your tank with the proper amount of oil. \\ Which means you have more oil to circulate through the engine which is a good thing.
  
-**So the answer is to address the oil density, not the oil level.**+**So the answer is to address the air/oil density, not the oil level.**
  
 +==== Removing the oil cap - engine running ====
  
 +With the oil cap off the tank on a hot idling engine (so far rigid S models only), the engine speed can drop app. 1,000 RPM at 1050 idle. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5763694#​post5763694)) \\
  
 +Another example with oil temp 210, raised idle to 1200 and lost 700 RPM. \\
 +So the exact power loss is variable but true. \\
 +Barely opening the cap or fully removing it had no affect on RPM. \\
  
 +This is the same as having a bad breather valve opening but not closing. \\
 +Oil doesn'​t puke out the tank since higher density suspension oil comes up the return line from the sump. \\
 +The suspension fluid and return oil together in the line helps to separate the oil back out of suspension by the time it reaches the tank. \\
 +The bulk of air / oil mist is generated in the crankcase, not the cam chest where the vent line to the tank is. \\
 +(leaving most of what comes out the top of the oil tank to be air). \\
 +The higher air/oil density drags the flywheels and more oil is picked up in suspension with the engine breathing both in and out. \\
 +The engine responds at idle from the higher load on the wheels. \\
 +Read more on [[techtalk:​ref:​engmech04#​fluid_drag|Fluid Drag]] above. \\
  
 +==== Venting the oil tank ====
 +Neither the oil cap nor the oil tank should be vented without a one way check valve / pcv. \\
 +The tank is vented to the cam chest on purpose to remove condensate (that gets pumped in) from the oil tank. \\
 +Venting the oil tank \ cap also will negatively influence crankcase venting by letting in extra air. \\
 +1/2 of the return flow is air because the return pump is twice as big as the feed pump. ((ryder rick of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1904589&​page=4)) \\
 +That air is full of condensate. \\
 +A slightly negative (to atmospheric) pressure in the tank facilitates vaporization of the condensate. \\
 +
 +====== Air Leaks ======
 +The breathing system is designed for a one-way valve venting system. \\
 +Air goes out but doesn'​t come back in. \\
 +Air leaks (into the engine) will increase positive pressure and air / oil density = oil puking out the breathers. \\
 +Some potential air leak areas are in the pic below. \\
 +If these areas allow air to be pulled in the engine on upstroke, the added air will compound any other existing breathing problems. \\
 +{{:​techtalk:​ref:​engmech:​potential_cc_pressure_leaks_at_the_rocker_box_by_daggar_rider_labeled_by_hippysmack.jpg?​direct&​300|}} ((photo by dagger rider of the XLFORUM )) {{:​techtalk:​ref:​engmech:​bad_rocker_box_fiber_washer_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack)) \\
  
 ====== Vacuum Pump for Reducing Crankcase Pressure ====== ====== Vacuum Pump for Reducing Crankcase Pressure ======
 +Most of the information on the web involves the use of a vacuum pump on autos. \\ There'​s not much published on using them with motorcycle engines. \\
 +That doesn'​t mean anything other than speed shops may not want to divulge their secrets. Also big pumps are for big displacement autos. \\
 +You can use a vacuum pump that's too big for a Sportster engine and cause more harm than good. \\
 +They are used for compensation as well as for better ring seal, but mostly advertised for better ring seal. \\
 +There are pumps spec'd for vacuum measurements and also ones spec'd by RPM range. \\
 +But, along with the addition of a vacuum pump, there is also the addition of a performance multi-stage oil pump. \\
 +If you vented from the crankcase area: \\
 +
 +Splash is an important element in the sump area. Too much vacuum and you lose scavenge ability of the oil pump. \\
 +You may be able to tap into the side-top with a vent line and a reed valve. \\
 +The more the vacuum, even lower the positive will begin. \\
 +The rings act as a buffer between these two conditions as excess pressure could run both directions. \\
 +But positive pressure aides in oil scavenging. \\
 +So lowering positive pressure by default also hinders scavenging. \\
 +That's why racers with vacuum pumps use multistage scavenge pumps to account for the imbalance to scavenge and improve it. \\
 +
 +Regardless, it's evident that some racers use vacuum pumps to increase vacuum pressure in the crankcase of a Sportster engine. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2073932)) \\
 +It's been said that positive crankcase pressure upon piston upstroke gets between the rings and basically causes bad sealing at the ringlands. \\
 +This is also in the high RPM range when ring flutter is present. So there are several things happening then. \\
 +But racers record higher power when using a vacuum pump. \\
 +However, it has also been said that inducing higher vacuum in a street engine may do more harm than good. Lower RPM may suffer from the imbalance. \\
 +
 A vacuum pump, in general, is an added benefit to any engine that is high performance enough to create a significant amount of blow-by. ((https://​www.gzmotorsports.com/​why-use-vacuum-pump.html)) \\ A vacuum pump, in general, is an added benefit to any engine that is high performance enough to create a significant amount of blow-by. ((https://​www.gzmotorsports.com/​why-use-vacuum-pump.html)) \\
 (that'​s high performance enough.... not worn enough) \\ (that'​s high performance enough.... not worn enough) \\
 It will, in general, add some horse power, increase engine life and keep oil cleaner for longer (in a high performance engine). \\ It will, in general, add some horse power, increase engine life and keep oil cleaner for longer (in a high performance engine). \\
 +
 +The first thing that happens on downstroke is that positive pressure (greater than atmosphere) is generated due to the restrictions of:
 +  * Case volume
 +  * Path to the vents
 +  * Vent hole size
 +  * Vent line (if applicable) length
 +  * Any induced air from the breather valve(s) not closing properly
 +
 +These things will bring the pressure inside to higher than atmosphere, else there would be nothing to expel. \\
 +As the air is pushed out of the vent, at BDC, the air returns to atmospheric. \\
 +That is the problematic condition, the higher pressure before returning to atmosphere. \\
 +Blowby adds to positive pressure which throws out the balance.
 +  * Using X (+1) as positive and Y (-1) as negative pressure.
 +  * In a perfect world, X goes down and Y comes up ------ X+Y=0.
 +  * Add ring blowby and you get ------ X+1>​Y------ or the real result. \\ Balance is off by nature of the moving parts. \\ The pistons move up and down almost together. \\ That makes the push/pull environment more violent.
 +  * Now add a vacuum pump with Z (-1) amount of pull. \\ Now you get X+1=Y-Z... seems the balance (to zero) is restored even though positive pressure is compiled of blowby. \\ But the lower the negative pressure is at the beginning of the downstroke, the lower the next positive pressure will be.
 +  * If you are generating 2 psi of positive pressure on downstroke but reduce it's beginning surge to -1 psi (Z), \\ the result will be only 1 psi of positive pressure during downstroke. \\ -1 (+) + 2 equals +1.
 +
  
 **Considerations for running a vacuum pump**: \\ **Considerations for running a vacuum pump**: \\