1977 V4 115 Evinrude

brandonsb22

brandonsb22

Seaman
Joined
Apr 4, 2008
Messages
59
I have read thru a good portion of previous advice. I would like alittle more specific advice or ideas.

I have a 1977 Evirude V4 115. It idles alittle rough, when I accelerate it bogs down around 2000 rpm and struggles; if I push thru this it will die if cold, if warm it comes back to full power and runs like a champ. Now lately it takes quite longer to reach full rpm and it seems to me that the carbs are not letting it open up all the way.I am not totally sure if I should decarb and run it real good on the water and/or rebuild the carbs. I have changed the plugs.
 
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ezeke

Supreme Mariner
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Sep 19, 2003
Messages
12,532
Re: 1977 V4 115 Evinrude

If the plugs are fouled with carbon, so are the firing chambers on the cylinders; take the plugs out and move the flywheel so that you can look at tops of pistons through the holes.

Do the de-carbon treatment as many times as necessary until you see clean metal on all pistons, then add carbon treatment to your fuel mix, make sure that the thermostat (vernatherm) is working properly, and be sure that the engine is not over-propped.

The motor will run best on Champion QL77JC4 plus gapped at .030.

Synthetic and synthetic blend TC-W3 oils will help decrease the plug fouling.
 
brandonsb22

brandonsb22

Seaman
Joined
Apr 4, 2008
Messages
59
Re: 1977 V4 115 Evinrude

Thank you for the quick response. I will give that a try. One other question is thru my researching on this site I over read that additives to your fuel besides stabilizers and seafoam do harm to the rings. Is this true with the carbon treatment?
 
brandonsb22

brandonsb22

Seaman
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Messages
59
Re: 1977 V4 115 Evinrude

Thanks again. Sorry but I have one more question. The link youl gave me I read thru it and at the bottom of the page it says that a omc outboard with over 100 hours should use Evinrude/Johnson Engine Tuner before running Carbon Guard?
 
brandonsb22

brandonsb22

Seaman
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Apr 4, 2008
Messages
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Re: 1977 V4 115 Evinrude

Should I go ahead and use the OMC Engine Tuner first? I believe the post I read said specifically that OMC Engine Tuner burns the rings up.
 
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emdsapmgr

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Dec 9, 2005
Messages
11,551
Re: 1977 V4 115 Evinrude

The Engine Tuner product should not damage the rings. It attacks the carbon deposit buildup around the pistons skirts, rings and in the combustion chamber-which is a common problem with the crossflow engines. You can use it anytime. Usually after a decarb on an engine suffering from carbon buildup, it will idle better and provide stronger performance. If you don't like to fiddle with adding the Carbon Guard additive to your fuel tank each time, you can switch to the Bombardier XD50 oil which has the carbon guard premixed in it.
 
brandonsb22

brandonsb22

Seaman
Joined
Apr 4, 2008
Messages
59
Re: 1977 V4 115 Evinrude

I may have to start using that carbon guard to fix the problem for long term reasons. But I believe I will be okay if I use straight Synthetic. Anyway I used your Decarb method tashdaddy but on muffs. It seemed to work very well. Spraying in the cylinders worked great. I have not yet water tested yet. I will let you all know. Thanks.
 
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