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techtalk:ih:engmech07l [2020/09/19 00:25] hippysmack |
techtalk:ih:engmech07l [2023/12/27 02:01] (current) hippysmack [Dr Dick on the slinger and oil loss] |
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| ====== IH: Engine Mechanicals - Sub-07L ====== | ====== IH: Engine Mechanicals - Sub-07L ====== | ||
| ====== Dr Dick on the slinger and oil loss ====== | ====== Dr Dick on the slinger and oil loss ====== | ||
| - | Article by Dr Dick of the XLFORUM ((http://xlforum.net/forums/showthread.php?t=1660412&page=2)) \\ | + | Article by Dr Dick of the XLFORUM ((https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/154643-generator-oil-slinger/page2?t=1660412&page=2)) \\ |
| - | 52-62 used the old 'daisy wheel' gear that physically sealed to a spring loaded top hat in the cover. \\ | + | 1952-1962 used the old 'daisy wheel' gear that physically sealed to a spring loaded top hat in the cover. \\ |
| These had great oil control but are pretty restrictive to air flow. Bad air flow can rob hi RPM horsepower. \\ | These had great oil control but are pretty restrictive to air flow. Bad air flow can rob hi RPM horsepower. \\ | ||
| Race bikes used big breather passages, fittings, hoses and pass lots more oil. \\ | Race bikes used big breather passages, fittings, hoses and pass lots more oil. \\ | ||
| - | Bikes 52-76 work different than 77>. \\ | + | Bikes 1952-1976 work different than 1977>. \\ |
| - | 77> don't have as much oil flying around in cam chest and the 77-78 one way foo foo keeps air flow volume to atmosphere low. \\ | + | 1977> don't have as much oil flying around in cam chest and the 1977-1978 one way foo foo keeps air flow volume to atmosphere low. \\ |
| These bikes tend to drip from the tube after a ride. Oil gets trapped in the nook and crannys of the foo foo, then leaks out. \\ | These bikes tend to drip from the tube after a ride. Oil gets trapped in the nook and crannys of the foo foo, then leaks out. \\ | ||
| - | 76< is a totally different dynamic. \\ | + | 1976< is a totally different dynamic. \\ |
| - | The crankcase volume under pistons is much smaller than 77> and air flow to the cam chest is much more restricted. \\ | + | The crankcase volume under pistons is much smaller than 1977> and air flow to the cam chest is much more restricted. \\ |
| - | The 77> cam chest can act as a air reservoir for crankcase volume and the foo keeps the amount air in the cases low. \\ | + | The 1977> cam chest can act as a air reservoir for crankcase volume and the foo keeps the amount air in the cases low. \\ |
| - | Less air equals less pumping losses. Used oil gets picked up in the crankcase itself (not in the camchest). \\ So the slinger has an easier task in 77>. | + | Less air equals less pumping losses. Used oil gets picked up in the crankcase itself (not in the camchest). \\ So the slinger has an easier task in 1977>. |
| - | Not so for 76<. \\ | + | Not so for 1976<. \\ |
| Oil collecting in the crankcase needs to be blown into the camchest to be picked up by the return pump. \\ | Oil collecting in the crankcase needs to be blown into the camchest to be picked up by the return pump. \\ | ||
| High air flow from the crankcase thru the timed breather to the camchest evacuates the crankcase oil good. \\ | High air flow from the crankcase thru the timed breather to the camchest evacuates the crankcase oil good. \\ | ||
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| They get the most power with the least chance of oil loss. \\ | They get the most power with the least chance of oil loss. \\ | ||
| A look at the shape of the transfer passage between the crankcase and the breather valve shows the result of that line of thinking. \\ | A look at the shape of the transfer passage between the crankcase and the breather valve shows the result of that line of thinking. \\ | ||
| - | So in mid 62, they reduced oil pump capacity but increased the return to feed ratio. Less oil in means less oil to move and less drag. \\ | + | So in mid 1962, they reduced oil pump capacity but increased the return to feed ratio. Less oil in means less oil to move and less drag. \\ |
| More return over pump helped more yet. \\ | More return over pump helped more yet. \\ | ||
| The small pump dried the camchest well enough that the slinger could be opened up = more air flow. \\ | The small pump dried the camchest well enough that the slinger could be opened up = more air flow. \\ | ||
| Good-bye power robbing daisy wheel - hello fender washer. \\ | Good-bye power robbing daisy wheel - hello fender washer. \\ | ||
| - | The 62-71 oil pump has a smaller feed side than the 61<. Compared to the 61<, the return is bigger in the -62 pump. Less feed, more return. ((http://xlforum.net/forums/showthread.php?t=1660412&page=3)) \\ | + | The 1962-1971 oil pump has a smaller feed side than the 1961<. Compared to the 1961<, the return is bigger in the -62 pump. Less feed, more return. ((https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/154643-generator-oil-slinger/page3?t=1660412&page=3)) \\ |
| - | The 72 pump feeds and returns more than any of the previous. | + | The 1972 pump feeds and returns more than any of the previous. |
