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techtalk:evo:engmech07 [2022/05/12 18:26] hippysmack [Late 1984-1990 Sportster Breather Valve] |
techtalk:evo:engmech07 [2022/05/12 18:35] hippysmack [Blowing through the vent] |
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| The oil on the soaked mesh can vapor off if it doesn't cool on shutdown and gunk up there. If it gunks up, the mesh should be pulled and cleaned or replaced. \\ | The oil on the soaked mesh can vapor off if it doesn't cool on shutdown and gunk up there. If it gunks up, the mesh should be pulled and cleaned or replaced. \\ | ||
| + | ===== Test for air flow at the vent ===== | ||
| You can verify a stopped up breather valve by "feeling" for air moving from the breather vent(s) with the air cleaner off, finger near each vent. \\ | You can verify a stopped up breather valve by "feeling" for air moving from the breather vent(s) with the air cleaner off, finger near each vent. \\ | ||
| As long as you have know air is moving, then the breather valve isn't stopped up. \\ | As long as you have know air is moving, then the breather valve isn't stopped up. \\ | ||
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| {{:techtalk:evo:engmech:2004-up_breather_vent_-_how_air_vacuum_closes_it_by_hippysmack.png?direct&500|}} ((drawing by Hippysmack)) \\ | {{:techtalk:evo:engmech:2004-up_breather_vent_-_how_air_vacuum_closes_it_by_hippysmack.png?direct&500|}} ((drawing by Hippysmack)) \\ | ||
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| + | ===== Blow testing through the vent ===== | ||
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| + | Since it's a one-way valve, air should go out but not come back in (past the umbrella itself). \\ | ||
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| + | Before you position the hose, you can use a bit of clean pipe and blow gently through the breather. ((Four Speed of the XLFORUM http://xlforum.net/forums/showthread.php?p=5745528#post5745528)) \\ | ||
| + | It should close the valve and stop air flow (if you use a quick hard breath). \\ | ||
| + | However, blowing slow and gently will allow a small amount of breath to go into the engine through the tiny oil drainback hole. \\ | ||
| + | You may have to find an aftermarket replacement if the valve is shot and OEM replacements are hard to come by. \\ | ||
| + | The 5 speed (rocker box) umbrellas are smaller than the 4 speed (cam cover) umbrellas and these won't interchange. \\ | ||
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