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techtalk:ref:engmech05g [2019/05/28 15:52] hippysmack |
techtalk:ref:engmech05g [2023/12/21 21:30] (current) hippysmack |
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| - | ====== REF: Oiling & Lubrication - Sub-05G ====== | + | ====== REF: Engine Mechanicals - Sub-05G ====== |
| ====== 86-90 Engine Breather Mod Using #4 Cam as an Oil Slinger ====== | ====== 86-90 Engine Breather Mod Using #4 Cam as an Oil Slinger ====== | ||
| + | Article by norseXL of the XLFORUM ((https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/179674-breathing-thru-the-cam?t=1930406&highlight=reed+valve)) \\ | ||
| + | |||
| + | This is an idea based from the breathing on the BMW Rotax twins. \\ | ||
| + | They have holes on the outer edge of the gear for the water-pump and the gear sits on the end of the inlet-cam. \\ | ||
| + | CC pressure exits the center of the cam without any oil in the air-box. \\ | ||
| + | |||
| + | The idea is to let the engine breathe thru one of the cams, thereby use the rotation to fling the oil out of the air. \\ | ||
| + | (preventing oil mist coming out when going fast over an extended period) \\ | ||
| + | |||
| + | This set-up is just to separate the oil from the air (thru the cam). \\ | ||
| + | Air comes into the cam thru an opening as far from the center of the cam as possible to let centrifugal force fling the oil out of the air. \\ | ||
| + | Then, the air exits the engine thru the center of the cam via an extension through the cam-cover. \\ | ||
| + | The cam is to have a fixed tube straight through the cam-cover and into the cam. \\ | ||
| + | And then a seal on the end of the cam where the tube goes in the cam cover. \\ | ||
| + | |||
| + | From there the air is fed through a reed or umbrella valve to atmosphere. \\ | ||
| + | |||
| + | In drilling the hole in the cam: \\ | ||
| + | The chances of either carbide or HSS drills working well are not high. ((Ireeman of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/179674-breathing-thru-the-cam/page3?t=1930406&highlight=reed+valve&page=3)) \\ | ||
| + | They tend to walk over the required distance. A gun drill is good or EDM is best for this process. \\ | ||
| + | You do not want to change to properties of the case hardening (which conventional even with coolant, drilling would do). \\ | ||
| + | |||
| + | A Tungsten carbide was used on the cam below and did work well. \\ | ||
| + | High speed-slow feed and thru the hard layer it went. \\ | ||
| + | Once the hardness is penetrated, it's best to swap to a cheap drill bit to drill through the softer inside of the cam. \\ | ||
| + | Feeding too fast through the soft part with the tungsten can snap the bit. \\ | ||
| + | |||
| + | **The plan**: \\ | ||
| + | In the drawing below, the engine pressure will go in between those two dishes (drawing is for example only... NTS). | ||
| + | The dishes should be as big in diameter as possible on the #4 cam (front ex). \\ | ||
| + | They will have, like pictured, a labyrinth to fling the oil from the air. \\ | ||
| + | Air will then exit the center of the cam into a fixed tube in the cam-cover. \\ | ||
| + | Then the oil seal ring on the end of the cam running on the tube. \\ | ||
| + | The back hole in the cam has to be plugged. \\ | ||
| + | It was just drilled from that end because it's easier to fit in the lathe. \\ | ||
| + | Without the plug, the air will not be forced to enter at a big radius/large centrifugal force. \\ | ||
| + | |||
| + | {{techtalk:ref:engmech:cam_breather_drawing_by_norsexl.jpg?direct&400|}} \\ | ||
| + | |||
| + | **Cam after drilling**: \\ | ||
| + | {{techtalk:ref:engmech:cam_breather_1_by_norsexl.jpg?direct&300|}} {{techtalk:ref:engmech:cam_breather_2_by_norsexl.jpg?direct&300|}} {{techtalk:ref:engmech:cam_breather_3_by_norsexl.jpg?direct&300|}} \\ | ||
| + | |||
| + | The hole in the outside end of the cam is for the breathing, it is the sole exit for the engine pressure. \\ | ||
| + | Air from that hole in the cam will go to an external reed valve. \\ | ||
| + | The original breather exit in the cam-case (4-speed) is to be plugged off. \\ | ||
| + | |||
| + | |||
