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techtalk:ref:oil05a [2019/06/04 23:20] hippysmack [High Pressure Oil Bypass] |
techtalk:ref:oil05a [2021/04/07 20:06] hippysmack [High Pressure Oil Bypass] |
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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. \\ | ||
+ | \\ | ||
+ | |||
**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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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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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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