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Low Compression on 50 HP Johnson 2-Stroke

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  • Low Compression on 50 HP Johnson 2-Stroke

    Hello folks. I have a 2000 Johnson 50 HP 2-stroke outboard that is suffering from low compression on one of the cylinders. I did a cold compression test and got a reading of 120 PSI on the top cylinder and just 30 PSI on the lower one. I read some instructions about trying a "wet" compression test so I sprayed the lower cylinder with some fogging oil and re-tried the test. PSI rose up to around 45-50 PSI. Is that a good sign?

    Seems like compression this low would mean major trouble but since the PSI raised after the "wet" test, maybe I should give decarbing a shot? The spark plug that came off the bad cylinder seems to have a sooty gray covering over it. I am a rookie when it comes to outboard motors so I'm looking for some much appreciated guidance. Thank you.