Johnson Seahorse 4hp Black Spark Plugs

[gsk2005uk]

Hello,

I noticed that after few minutes of starting the engine the new spark plugs became black as if they are burned or something.

I read some thread that mentioned that this might be from "running rich". What does that mean and do I need to do anything about it? Note: Carb is clean and has just been fitted with new kit.

 

[Rick.]

Re: Johnson Seahorse 4hp Black Spark Plugs

It could be you need to decarb your engine if it has been running rich for a long time. Yes a black plug is an indication of a rich mix. I will assume that your using the correct fuel mix of 50/1. Turn your slow speed idle knob in (clockwise), in 1/8th increments, until your engine starts to sneeze (like a miss). From that point turn the knob richer until the sneeze disappears and it should be good to go. Best of luck. Rick.

 

[tashasdaddy]

Re: Johnson Seahorse 4hp Black Spark Plugs

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.