Decarboning - Which Method?

phipps

Petty Officer 1st Class
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Jul 20, 2008
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385
Reading through the boards here I have come across three different methods for decarbing a motor. I have listed them below; is one method any better than the others?


Method 1: 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.


Method 2: You'll need 3/4 gallon of gasoline and one 16oz can of Seafoam for each engine. Don't forget to add 3oz of oil if you are pre-mixing in a carbed engine. Use a 3 ft piece of fuel hose off the small tank. Connect this tank to your engine by pulling off the main tank fuel hose from the intake side of your water separating fuel filter and plug the hose off the small tank onto that fitting. Or you can separate the fuel line on the tank side primer ball, so you can still use your primer. If your engine has a fuel plug then you will also need a fuel plug on the smaller tank's hose. Start the engine, let it warm up and start pulling the mix into the engine. You may have to increase the idle to keep it running once she gets loaded with the Seafoam. Run the engine 15 minutes at the dock or just cruising around under 2500 rpm's. Then shut it down and let it sit for another 15 minutes. Restart the engine; the smoke you see is the carbon burning off. Do the whole thing again and let her sit again for 15 more minutes. If she smokes after the second time do it again. I've never seen one still smoke after three doses.


Method 3: Run engine at fast idle, with engine running and warm, slowly spray liberal amount into each carb. Its gonna smoke up the place. Spray for a couple minutes, now spray a larger amount into the carb(s) until engine chokes out and stops. Remove spark plugs and spray the decarb product liberally into each cylinder, install the spark plugs, let it soak for an hour or more. Start the engine and run at medium throttle, or if at the lake, run it at full throttle. It won't hurt to spray some more through the carbs. Run it for atleast 10 minutes to flush the crud out of your engine. Now remove and clean, or replace the spark plugs.
 

5150abf

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Aug 12, 2007
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5,808
Re: Decarboning - Which Method?

I have used 2-3,both work about the same except with 2 the mix is going through the carb passages which is good.

The important thing is that you get it done, which way you do it doesn't matter they all work, if you live an hour from the nearest launch then use 3, if you are 10 minutes away and you have the time use 1-2.

Depending on how long it has been it will make ALOT of smoke so probably get to a less populated area to do this, don't want anyone to call the fire department thinking your boat is on fire.
 

Silvertip

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Sep 22, 2003
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28,762
Re: Decarboning - Which Method?

Once you've done this process (any of the three methods), continue to use SeaFoam in each tank of fuel and you will not have to repeat the process as frequentlly although it certainly doesn't hurt.
 

phipps

Petty Officer 1st Class
Joined
Jul 20, 2008
Messages
385
Re: Decarboning - Which Method?

Thanks for the replies. Ive already started running Seafoam in the tank. Just need to do the decarb.

I just replaced the plugs, will I need to replace them again after a decarb?
 

gss036

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Jan 18, 2003
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Re: Decarboning - Which Method?

Why not put your old plugs back in the engine for the decarb?
 

Silvertip

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Re: Decarboning - Which Method?

The answer to the question about whether or not the plugs need to be replaced after decarb is simply -- check them. If they are gunked up after a long run, replace them. If they haven't been replaced in awhile, replace them anyway. This is not a major expense.
 

mthieme

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Oct 6, 2007
Messages
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Re: Decarboning - Which Method?

Any auto mechanic can tell you to run ATF through the carb at high idle. Do NOT let the engine die so you don't to go through pulling the plugs. Much carbon comes out of the tailpipe with this method. It is also referred to as a poor man's valve job.
 

tashasdaddy

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51,019
Re: Decarboning - Which Method?

i would not put ATF in my outboard. i wrote the 1st set of directions, and have used it with great success. even on the weedeater, blower, my 2 cycle scooter. also if you have clean carbs, i agree with Silvertip, and use seafoam as an additive, it will keep clean carbs clean, but will not clean a dirty carb.
 

gss036

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Jan 18, 2003
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Re: Decarboning - Which Method?

The use of transmission fluid to clean the valves in an engine came about in 4 cycle auto/truck engines and it does work very well. Again.
I would not use it in a 2 stroke engine. I am a true believer in the use of SeaFoam in 2 stroke engines and in smaller 2 stroke if you do a lot of trolling as this allows for carbon build up.
I also use SeaFoam in auto engines. Pull the power brake vaccum line and suck a can into it and then let your engine/vehicle sit for an hour or so, just be sure no one is behind you as you start down the road.
 
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