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techtalk:ref:oil05a [2019/06/04 23:06] hippysmack [Homemade Oil System Bypass (OSB)] |
techtalk:ref:oil05a [2021/04/07 20:06] hippysmack |
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| ====== REF: Oiling & Lubrication - Sub-05A ====== | ====== REF: Oiling & Lubrication - Sub-05A ====== | ||
| ====== High Pressure Oil Bypass ====== | ====== High Pressure Oil Bypass ====== | ||
| + | **This is a Race Only Mod - Install this mod at your own risk!**. \\ | ||
| + | This mod can also be installed on motors with EXTREME wetsumping issues. \\ | ||
| + | Generally speaking, if a street motor wet sumps bad enough to NEED this mod, there are many more items to check off that might need attention instead. \\ | ||
| + | \\ | ||
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| **Theory behind installing a high pressure bypass**: \\ | **Theory behind installing a high pressure bypass**: \\ | ||
| The supply side of the oil pump is over supplying oil to the crank case during sustained high RPM running. \\ | The supply side of the oil pump is over supplying oil to the crank case during sustained high RPM running. \\ | ||
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| When the sump gets wet, the crank sees a lot of resistance due to the oil pooling there. \\ | When the sump gets wet, the crank sees a lot of resistance due to the oil pooling there. \\ | ||
| This generates a lot more heat meeting the power demands while overcoming the added drag of the oil on the flywheels. \\ | This generates a lot more heat meeting the power demands while overcoming the added drag of the oil on the flywheels. \\ | ||
| - | |||
| - | The combination of the added heat and increased pumping to the top end of the motor results in oil pooling on top of the heads that is thinned by the heat. \\ | ||
| - | The combination of pooling and thinner oil with the increased vacume provided by the motor at high RPMs sucks the oil past the valve guides. \\ | ||
| Just adding a cooler may not solve this problem. \\ | Just adding a cooler may not solve this problem. \\ | ||
| You need to get the oil out of the crankcase so it does not interfere with motion of the crank and cause the heating problem in the first place. \\ | You need to get the oil out of the crankcase so it does not interfere with motion of the crank and cause the heating problem in the first place. \\ | ||
| - | The proposed approach is to bleed off excess high pressure oil from the feed side of the oil pump. \\ | + | To regulate the oil pressure you have to bleed some of it off. ((aswracing of the XLFORUM http://xlforum.net/forums/showpost.php?p=4341107&postcount=6)) \\ |
| + | 4-speeds have a spring loaded pressure regulator built into the oil filter pad that does exactly that. \\ | ||
| + | There's a passage from the filter pad into the cam box. \\ | ||
| + | If the pressure gets high enough, the regulator opens and bleeds off some of the pressurized oil, dropping it into the cam box. \\ | ||
| + | Then it eventually drains down to the crankcase and gets pumped back to the tank. \\ | ||
| + | They did away with the pressure regulator on 92 and up 5-speed XL's though. \\ | ||
| + | Evo Big Twins have a spring loaded bleed-off regulator, as do Twinkies, XR1200's, and 08-up Buells. \\ | ||
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| + | Some have found it useful to build bypass circuits to bleed off excess oil pressure and send it back to the tank. \\ | ||
| Such that the scavaging side of the pump will be able to evacuate the oil from the crankcase before it starts to wet sump and generate the added heat. \\ | Such that the scavaging side of the pump will be able to evacuate the oil from the crankcase before it starts to wet sump and generate the added heat. \\ | ||
| + | But this does reduce oil pressure across the board, as opposed to opening a bypass when the pressure exceeds a certain point. \\ | ||
| + | |||
| + | {{:techtalk:ref:oil:oil_pressure_bypass_mod_14_by_aswracing.jpg?direct&300|}} ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showpost.php?p=4341107&postcount=6)) | ||
| ====== Homemade Oil System Bypass (OSB) ====== | ====== Homemade Oil System Bypass (OSB) ====== | ||
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| ====== Conclusions ====== | ====== Conclusions ====== | ||
| **Understand why you would need to install this mod**: \\ | **Understand why you would need to install this mod**: \\ | ||
| - | This mod is not meant as a cure for high oil temps at or above highway speeds. \\ | + | This mod is __not__ meant as a cure for high oil temps at or above highway speeds. \\ |
| It was designed as a fix for wet sumping during high revs in the interest of gaining (or rather not losing) horsepower due to wet sumping. \\ | It was designed as a fix for wet sumping during high revs in the interest of gaining (or rather not losing) horsepower due to wet sumping. \\ | ||
| - | Some ride reports are below from XLFORUM members trying this mod to solve oil temp problems. \\ | + | Some ride reports are above from XLFORUM members trying this mod to solve oil temp problems. \\ |
| Reported were cooler temps at higher RPMs but lifter noise (presumed from oil starvation) during low or idle conditions. \\ | Reported were cooler temps at higher RPMs but lifter noise (presumed from oil starvation) during low or idle conditions. \\ | ||
| So this mod reportedly does work to control wet sumping and temps at higher RPMs due to wet sumping. \\ | So this mod reportedly does work to control wet sumping and temps at higher RPMs due to wet sumping. \\ | ||
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| Later, a cam chest breather mod was discovered by Deimus of the XLFORUM that was deemed a fix for better crankcase venting. \\ | Later, a cam chest breather mod was discovered by Deimus of the XLFORUM that was deemed a fix for better crankcase venting. \\ | ||
| That mod did reduce crankcase pressure allowing for lower engine temps. | That mod did reduce crankcase pressure allowing for lower engine temps. | ||
| - | You can read about it here in the Sportsterpedia: [[techtalk:ref:oil05d|Installing the Ultimate Crankcase Vent]]. \\ | + | You can read about it here in the Sportsterpedia: [[techtalk:ref:engmech05d|Installing the Ultimate Crankcase Vent]]. \\ |
| **Coincidence**? \\ | **Coincidence**? \\ | ||
| This mod is not so different than what the MoCo has already done to 92 and up engines. \\ | This mod is not so different than what the MoCo has already done to 92 and up engines. \\ | ||
| - | When the factory got rid of the 86-90 oil pressure regulator, they introduced a oil bleed passage in the oil feed galley of the right case. \\ | + | When the factory got rid of the 86-91 oil pressure regulator, they introduced an oil bleed passage (tiny hole) in the oil feed galley of the right case. \\ |
| This relieves some of the pressure while giving some extra oil to the cam gears by way of splashing #2 cam from the feed galley. \\ | This relieves some of the pressure while giving some extra oil to the cam gears by way of splashing #2 cam from the feed galley. \\ | ||
| + | |||
| + | So, on 92 and up engines, one could also say this mod will add a second pressure relief to the feed oil system. \\ | ||
| + | The jet size for this mod may need to be adjusted for these engines. \\ | ||
| + | (to make sure there is still enough pressure to keep proper oil to the lifters during hot idle or low speeds) \\ | ||
| + | |||
| + | | 98 cam chest. ((photo by isiahstites of the XLFORUM and labeled by Hippysmack http://xlforum.net/forums/showthread.php?t=51598&page=5)) | | ||
| + | |{{:techtalk:evo:oil:98_cam_chest_by_isiahstites.jpg?direct&300|}}| | ||
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| \\ | \\ | ||
