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techtalk:ref:engmech07s [2020/10/05 17:32] hippysmack [XR-750 Breather Valve] |
techtalk:ref:engmech07s [2020/10/07 00:12] hippysmack [XR-750 8-Ball Breather Valve] |
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| ====== REF: Engine Mechanicals - Sub-07S ====== | ====== REF: Engine Mechanicals - Sub-07S ====== | ||
| - | ====== XR-750 Breather Valve ====== | + | ====== XR-750 8-Ball Breather Valve ====== |
| + | The earliest alloy XR's put a vent to the back of the crankcase with a big one-way valve on it. ((barefoot of the XLFORUM http://xlforum.net/forums/showthread.php?t=1982389&page=6)) \\ | ||
| + | The idea was, when the pistons go down it pushes the oil into the camcase and scavenge pump. \\ | ||
| + | But when the pistons go up, it creates a vacuum in the crankcase that sucks some of that oil back in. \\ | ||
| + | By putting a one-way (valve) into the crank area, they were trying to suck air in from the outside on the upstroke, then push it into the cam case on the downstroke. \\ | ||
| + | (more of a continuous flow of air/oil mix to the scavenge system than a backy-forthy one. Get the oil out of the crank area was the idea. \\ | ||
| + | They quit doing that when they went to the mini-sump, since that's a different system entirely. \\ | ||
| - | Here is the breather hole in the rear of the crankcase where the 8-ball breather assembly is fitted. \\ | + | The 8-ball breather was designed to handle 45 cu. in. of volume. ((mrmom9r of the XLFORUM http://xlforum.net/forums/showthread.php?t=2041173&page=3)) \\ |
| - | {{:techtalk:ref:engmech:1972_xr-750_8-ball_breather_hole_in_case_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?p=4148222#post4148222)) \\ | + | The first pic below shows the 3/4" tapped hole in the case behind the rear cylinder where the 8-ball breather assembly is fitted. \\ |
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| + | {{:techtalk:ref:engmech:1972_xr-750_8-ball_breather_hole_in_case_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?p=4148222#post4148222)) {{:techtalk:ref:engmech:1972_xr-750_crankcase_breather_by_brucstoudt.jpg?direct&300|}} ((photo by brucstoudt of the XLFORUM, cropped by Hippysmack http://xlforum.net/forums/showthread.php?t=2077883)) {{:gallery:iron:1972_xr-750_by_brucstoudt.jpg?direct&300|}} ((photo by brucstoudt of the XLFORUM http://xlforum.net/forums/showthread.php?t=2077883)) \\ | ||
| ====== Notes from XLForum Members on the 8-Ball Breather ====== | ====== Notes from XLForum Members on the 8-Ball Breather ====== | ||
