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techtalk:ref:svcproc21 [2019/01/09 04:09] ixl2relax ↷ Links adapted because of a move operation |
techtalk:ref:svcproc21 [2021/07/31 22:47] hippysmack [Engine Prep] |
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| * See [[techtalk:ref:svcproc20|Performing a Compression Test]] in the REF section of the Sportsterpedia. | * See [[techtalk:ref:svcproc20|Performing a Compression Test]] in the REF section of the Sportsterpedia. | ||
| * Generally if a compression test shows anything suspect, the next step is a leak down test. ((milmat1 of the XLFORUM http://xlforum.net/forums/showthread.php?t=26208&page=2)) | * Generally if a compression test shows anything suspect, the next step is a leak down test. ((milmat1 of the XLFORUM http://xlforum.net/forums/showthread.php?t=26208&page=2)) | ||
| - | * A leak-down test checks the cylinder's ability to hold pressure (seal) and will reflect where the leak is occuring. | + | * A leak-down test checks the cylinder's ability to hold pressure (seal) and will reflect where the leak is occuring. \\ A leak down test is the best way to check the mechanical integrity of the motor without tearing it down. ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=15705)) |
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| **Piston position**: | **Piston position**: | ||
| * You can leak test a cylinder at any position so long as the valves are closed. However, TDC on Compression stroke is the accepted practice for this test. | * You can leak test a cylinder at any position so long as the valves are closed. However, TDC on Compression stroke is the accepted practice for this test. | ||
| - | * On a worn cylinder, the most wear is usually in the top inch or so, that is why there is a noticeable ridge there on a worn jug. The least wear is at the bottom inch or so. \\ So I if you want the acid test of how the rings are sealing, it should be done at or close to TDC. Put the bike in high gear to stop piston moving. ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=48311&page=2)) | + | * On a worn cylinder, the most wear is usually in the top inch or so, that is why there is a noticeable ridge there on a worn jug. The least wear is at the bottom inch or so. \\ So if you want the acid test of how the rings are sealing, it should be done at or close to TDC. Put the bike in high gear to stop piston moving. ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=48311&page=2)) |
| * The test takes only a few seconds to repeat so you can also test several locations as long as both valves are closed. | * The test takes only a few seconds to repeat so you can also test several locations as long as both valves are closed. | ||
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| **Put the transmission in high gear and hold / lock the rear brakes**: | **Put the transmission in high gear and hold / lock the rear brakes**: | ||
| - | * During the leak-down test, when you apply the air pressure to the cylinder, the piston will try to be driven downward. If allowed to move, it can quickly turn the engine over, while turning the rear wheel. (How much the bike will jump depends on the gauge/pressure you're using.) | + | * During the leak-down test, when you apply the air pressure to the cylinder, the piston will try to be driven downward. \\ If allowed to move, it can quickly turn the engine over, while turning the rear wheel. (How much the bike will jump depends on the gauge/pressure you're using.) |
| * Therefore, secure the wheel by applying the rear brakes or it will just turn over the engine and open the exhaust valve. ((skyboltdan of the XLFORUM http://xlforum.net/forums/showthread.php?t=48311)) | * Therefore, secure the wheel by applying the rear brakes or it will just turn over the engine and open the exhaust valve. ((skyboltdan of the XLFORUM http://xlforum.net/forums/showthread.php?t=48311)) | ||
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| - | * The actual numbers are not as important as the relationship of each cylinder. As long as both juggs are close to each other, don't sweat the actual readings. There are lots of variables that can affect those readings. ((scottfisher of the XLFORUM http://xlforum.net/forums/showthread.php?t=48311&page=3)) | + | * The actual numbers are not as important as the relationship of each cylinder. As long as both jugs are close to each other, don't sweat the actual readings. There are lots of variables that can affect those readings. ((scottfisher of the XLFORUM http://xlforum.net/forums/showthread.php?t=48311&page=3)) |
| * Make a note of the reading and the date you took it, check it again after a few rides and see if it reads the same using the same equipment. ((scottfisher of the XLFORUM http://xlforum.net/forums/showthread.php?t=48311&page=3)) | * Make a note of the reading and the date you took it, check it again after a few rides and see if it reads the same using the same equipment. ((scottfisher of the XLFORUM http://xlforum.net/forums/showthread.php?t=48311&page=3)) | ||
