| Author |
Message |
    
Mack1015 (Mack1015)
| | Posted on Wednesday, January 22, 2003 - 09:14 pm: | 
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I have a 1971,20hp Johnson. I ran a compression test on both cylinders, one was 90 and the other was 91psi. I ran the test with both spark plugs out and no fuel hooked up.The engine had not been started in about 3 mth.I pulled the engine thru 8 times on both cylinders. Is this compression OK for this old of and engine, and if not is there anything that I can do to help? Mack |
sparky
| | Posted on Wednesday, January 22, 2003 - 09:29 pm: |
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The fact that they are even is a good indication.Age of an engine has no bearing on condition , the amount of use and abuse does.The motor that you have was basically the same from 58 to 77 ( same crankshaft ) and is a proven design. |
Rick
| | Posted on Wednesday, January 22, 2003 - 09:48 pm: |
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To answer your question Mack, 90 is good. |
Tonyob (Tonyob)
| | Posted on Thursday, January 23, 2003 - 10:29 am: |
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Mack,
90 psi is probably okay, but it is also important that the compression comes up quickly. I generally crank the engine for 4 cycles. If the compression is not acceptable after four cycles I feel that the rings are worn.
You can count the cycles by watching the needle on the compression gauge.
Tony |
Jon
| | Posted on Thursday, January 23, 2003 - 10:54 am: |
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Mack,
My 2001 25 HP Johnson, with under 10 hours, has an even 90 psi on each. I'd say that engine is tip top.
Jon |
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