| Author | Message | ||
     Whosbeenfartin |
I performed a compression test today, engine nice and hot, and had ~100 PSI compression front Dry, ~135 or so wet, and ~95psi rear dry with ~130 wet. Does this indicate a combination of worn valves and warn rings er what? I will be replacing the cylinder base gaskets as both are leaking, so should I do maybee a 1250 kit and a valve job at the same time? Would there be a significan power gain in doing headwork beyond just a valve job? thanks... (Message edited by whosbeenfartin on October 07, 2007) | ||
| Mmmi_grad |
How many miles on this engine? If you did the test below by the book and your not having a problem then I wouldnt worry about it its close enough. the rest is up to you. Piston wear or problems with rings, oil consumption can show up before a bad valve seal or need of a valve job. When you have the cyl off. Max piston to cyl. clearance is .006" by harley standards. Piston slap becomes a worry any looser than that etc etc. Since our bikes are high performance bla bla bla what YOU want plays a big role here. If it was my bike and I had those leaks I would measure and if it .003 -.004 id cross hatch the cyl and throw in some new rings. Sure a 1250 kit sounds good if ya got the bread. There isnt any concern about it either. the injectors will feed it and it will run good. Headwork isnt done for nothing. But headwork can be a cause of concern for the fuel injection on our bikes. You can only go so far. I forgot what Nallin guy told me, sorry. Yeah id be interested to hear about some succesful setups with a 1250 kit with or without headwork and fuel injection. Compression Test Procedure Combustion chamber leakage can result in unsatisfactory engine performance. A compression test can help determine the source of cylinder leakage. Use CYLINDER COMPRESSION GAUGE (Part No. HD-33223-1). A proper compression test should be performed with the engine at normal operating temperature when possible. Proceed as follows: CAUTION After completing the compression test(s), make sure that the throttle plate is in the closed position before starting engine. Engine will start at an extremely high RPM if throttle plate is left open. 1. Disconnect spark plug wires. Clean around plug base and remove plugs. 2. Connect compression tester to front cylinder. 3. With throttle plates in wide open position, crank engine continuously through 5-7 full compression strokes. 4. Note gauge readings at the end of the first and last compression strokes. Record test results. 5. Connect compression tester to rear cylinder. 6. Repeat Steps 3 and 4 on rear cylinder. 7. Compression is normal if final readings are 120 psi (827 kN/m 2 ) or more and do not indicate more than a 10 psi (69 kN/m 2 ) variance between cylinders. See Table 3- 1. 8. Inject approximately 1/2 oz. (15 ml) of SAE 30 oil into each cylinder and repeat the compression tests on both cylinders. Readings that are considerably higher during the second test indicate worn piston rings. Table 3-1. Compression Test Results DIAGNOSIS TEST RESULTS Ring trouble Compression low on first stroke; tends to build up on the following strokes but does not reach normal; improves considerably when oil is added to cylinder. Valve trouble Compression low on first stroke; does not build up much on following strokes; does not improve considerably with the addition of oil. Head gasket leak Same reaction as valve trouble. | ||
| Whosbeenfartin |
Thats pretty much the compression test procedure I used. The only thing a do differenly is I like to add initially about a t spoon of oil for an initial test before putting in 15cc's which is about a half ounce. So I do the test multiple times with the oil. Reading that procedure really points to worn rings. The bike probably has 15-20K miles. The ODO was not functional when I got it, but there wouldn't be much opertunity for it to be much beyond 20K unless the PO rode over 8K miles in 6 months. I may borrow a cyl leakdown tester and try that to really get a handle on whats wrong. (Message edited by whosbeenfartin on October 08, 2007) (Message edited by whosbeenfartin on October 08, 2007) | ||
| Natexlh1000 |
Bad air filter or something? |
