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techtalk:ref:svcproc20 [2020/03/02 05:38] hippysmack |
techtalk:ref:svcproc20 [2024/01/21 21:21] hippysmack |
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| ====== REF: Service Procedures 20 ====== | ====== REF: Service Procedures 20 ====== | ||
| ====== Cylinder Compression Test ====== | ====== Cylinder Compression Test ====== | ||
| - | A compression test should be done as part of each tune-up. Record the results and follow any changes over time. ((IronMick of the XLFORUM http://xlforum.net/forums/showthread.php?t=48311)) \\ | + | A compression test should be done as part of each tune-up. Record the results and follow any changes over time. ((IronMick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/29105-cylinder-compression-and-leakage-tests-for-your-ironhead?t=48311)) \\ |
| * The compression tester has a one-way valve in it's hose, allowing it to see the pressure of the compression stroke\\ but not relieve it on the other strokes. Additional strokes that produce higher pressures will increase the\\ reading of the gauge. | * The compression tester has a one-way valve in it's hose, allowing it to see the pressure of the compression stroke\\ but not relieve it on the other strokes. Additional strokes that produce higher pressures will increase the\\ reading of the gauge. | ||
| * Always look for a compression tester that has it's check valve as near to the chamber as possible. Otherwise, you're\\ adding the volume of the hose (up to the check valve) to the chamber volume which causes the compression reading\\ to be lower, because the piston is trying to fill that hose space as well as the chamber. ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=26208&page=2)) | * Always look for a compression tester that has it's check valve as near to the chamber as possible. Otherwise, you're\\ adding the volume of the hose (up to the check valve) to the chamber volume which causes the compression reading\\ to be lower, because the piston is trying to fill that hose space as well as the chamber. ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=26208&page=2)) | ||
| * A proper compression test should be done with the engine close to normal operating temperature, when possible. ((79-85 HD XL/XR FSM pg 3-10)) | * A proper compression test should be done with the engine close to normal operating temperature, when possible. ((79-85 HD XL/XR FSM pg 3-10)) | ||
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| ===== Compression Test vs Leak-Down Test ===== | ===== Compression Test vs Leak-Down Test ===== | ||
| - | + | * These are both fancy names for a deceptively simple process (installing an air gauge in the spark plug hole and noting the results). ((GOTWA of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-motor-top-end/15672-four-strokes-and-leak-down-compression-tests-how-they-work?t=26208)) | |
| - | * These are both fancy names for a deceptively simple process (installing an air gauge in the spark plug hole and noting the results). ((GOTWA of the XLFORUM http://xlforum.net/forums/showthread.php?t=26208)) | + | |
| * A compression test checks the cylinder's maximum pressure ability. A low reading reflects poor sealing of the chamber. | * A compression test checks the cylinder's maximum pressure ability. A low reading reflects poor sealing of the chamber. | ||
| - | * 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 https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-motor-top-end/15672-four-strokes-and-leak-down-compression-tests-how-they-work/page2?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. | ||
| * See also [[techtalk:ref:svcproc21|Performing a Leak-Down Test]] in the REF section of the Sportsterpedia. | * See also [[techtalk:ref:svcproc21|Performing a Leak-Down Test]] in the REF section of the Sportsterpedia. | ||
| - | |||
| ====== Test Each Cylinder for Compression ====== | ====== Test Each Cylinder for Compression ====== | ||
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| ====== Compression Calculator ====== | ====== Compression Calculator ====== | ||
| + | Article by aswracing of the XLFORUM ((http://xlforum.net/forums/showthread.php?t=1441757)) and Hammer Performance site. (( http://hammerperf.com/ttcompression.shtml)) \\ | ||
| + | |||
| + | [[http://hammerperf.com/ttcompression.shtml|Click here to download a free copy of the HAMMER PERFORMANCE Compression Calculator]]. \\ | ||
| So how much compression can you run with what cams, and still be able to run pump gas? \\ | So how much compression can you run with what cams, and still be able to run pump gas? \\ | ||
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| To solve the problem, you need to dust off your trigonometry textbook and make right triangles out of it. \\ | To solve the problem, you need to dust off your trigonometry textbook and make right triangles out of it. \\ | ||
| - | Or, you could take the easy way and [[http://hammerperf.com/ttcompression.shtml|click here to download a free copy of the HAMMER PERFORMANCE Compression Calculator]]. \\ | + | Or, you could take the easy way and just download the calculator. \\ |
| Store the file somewhere on your hard drive where it's easy to find, and then double click on it to execute. \\ | Store the file somewhere on your hard drive where it's easy to find, and then double click on it to execute. \\ | ||
| - | |||
| The program is very easy to use, and it will give progressively more info as you enter more data: \\ | The program is very easy to use, and it will give progressively more info as you enter more data: \\ | ||
| * For just displacement, enter the bore and stroke. | * For just displacement, enter the bore and stroke. | ||
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| With good chamber turbulence and dual plugs, you can even run it higher, up to 9.5:1 is not unusual. \\ | With good chamber turbulence and dual plugs, you can even run it higher, up to 9.5:1 is not unusual. \\ | ||
| - | This is a free tool, independently developed in-house by aswracing of the XLForum (Hammer Performance). \\ | + | This is a free tool, independently developed in-house by Hammer Performance ((aswracing of the XLForum)). \\ |
| Feel free to use it and distribute it as you please. \\ | Feel free to use it and distribute it as you please. \\ | ||
| It's virus-free. \\ | It's virus-free. \\ | ||
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| All it does is perform the calculations and give you the answer. \\ | All it does is perform the calculations and give you the answer. \\ | ||
| + | Note that results given by this program are intended as a guideline only. \\ | ||
| + | HAMMER PERFORMANCE assumes no responsibility for what you do with the information presented. \\ | ||
| {{:techtalk:ref:svcproc:compression_calculator_screeenshot_1_by_aswracing.jpg?direct&400|}} ((screenshot by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1441757)) {{:techtalk:ref:svcproc:compression_calculator_screeenshot_2_by_aswracing.jpg?direct&400|}} ((screenshot by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1441757)) \\ | {{:techtalk:ref:svcproc:compression_calculator_screeenshot_1_by_aswracing.jpg?direct&400|}} ((screenshot by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1441757)) {{:techtalk:ref:svcproc:compression_calculator_screeenshot_2_by_aswracing.jpg?direct&400|}} ((screenshot by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1441757)) \\ | ||
