compression numbers for 9.8 epul

[spiritofstsimons]

I have a pair of 9.8 tohatsu I plan to sell. I have never done a compression test before today. I bought a compression checker from the auto parts store, removed the spark plugs, screwed the gauge in, and pulled the start cord several times. Here is what I got: engine #1 -120psi and 119psi. engine #2- 155psi and 140 psi. This was the first run at it. Engines were cold. ambient temp about 60 degrees F. Oil had just been changed but engines have not been run since oil change. Each engine has about 900 hours on them, and are six years old. QUESTION are these numbers acceptable? is there anything I should be doing or doing different? Thanks!

 

[spiritofstsimons]

Well I did the test again today. This time I ran them for a few minutes to dry out the carbs. The numbers were all around 120. Highest was 129, lowest was 119. I think I probably am not pulling the cord hard enough sometimes, to get apples to apples. The manual says 128 psi., so I think I am good. I just wonder why the numbers were so much higher on one yesterday when they were cold and maybe hadn't been turned over enough to circulate the new oil?

 

[pvanv]

Hard to say. The 9.8 does not have decompression, so those numbers sound typical. Of course gauges vary. Big thing is pressures within 10% of each other.