De-Carb Procedure
Printed From: The Fishing Website
Category: General Forums
Forum Name: The Outboard Clinic
Forum Description: Anything related to outboard maintenance here....
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=91102
Printed Date: 11 Jun 2026 at 7:50am
Topic: De-Carb Procedure
Posted By: HuntGatherRepeat
Subject: De-Carb Procedure
Date Posted: 21 May 2013 at 4:23pm
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I've got an older Evinrude 90hp 2 Stroke pushing the boat around and I think she's due for a birthday. Owned it for about 2 months now and haven't had any trouble but better safe than sorry and with no real maintenance records it couldn't hurt to start fresh. What's everyone using for a de-carbing chemical? Are you allowing it to sit overnight or just mixing up and running a tote tank while out and about? |
Replies:
Posted By: Durban
Date Posted: 21 May 2013 at 4:37pm
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depends how long the fuel has been left in the carb ,if left for long periods the fuel evaporates & leaves a sort of varnish behind in the main jets , idle jets , & high speed jets depending wot carb you have in this case strip it down &soak it over night & get a thin steel wire to clean the varnish out that has gone hard in the jets as it blocks the tiny little fuel holes in the jets then blast with compressed air |
Posted By: HuntGatherRepeat
Date Posted: 21 May 2013 at 5:58pm
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Cheers for that mate, not quite what I was talking about though. I see a lot of people running a mix through the engine to remove carbon build up around piston rings, exhaust ports etc. In the US Sea Foam is pretty popular, you essentially run your engine on a 50/50 mix of it and fuel until it stalls, leave it for the night to soften the carbon buildups and then run it on the water the next day and it blows all of the carbon out and cleans the combustion chambers. I haven't found anything equivalent in NZ yet. Wondered what others were doing to clean the engine internals. |
Posted By: HuntGatherRepeat
Date Posted: 21 May 2013 at 6:02pm
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Here is a link to the procedure some other members use. All I'm after are some opinions on chemicals that are up to the task. http://www.fishing.net.nz/asp_forums/decarbs_topic37202.html |
Posted By: Durban
Date Posted: 21 May 2013 at 6:26pm
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yea sea foam seems to be a very popular product in the US , Its for this reason i run on synthetic oil to reduce carbon build up in the motor & especially in the ring grooves |
Posted By: Ohsoslow
Date Posted: 21 May 2013 at 7:35pm
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Hey mate, I've run seafoam through my engine, seems to do the job, but can't say I've "needed" to do it as such, have just done it as part of the maintenance. All I did was get a container of the stuff, put it in a spray bottle, then while motor at a fast idle, spray into the intakes until motor chokes out (Mine didn't quite conk out completely, maybe because it's a v6) And then wait about 20 minutes before firing it up again and giving it a decent burst of throttle under load. I have heard of people leaving it overnight etc, and running it through a tote tank, but for me personally I didn't see the need. (when I stripped motor down to do gaskets etc, there was minimal carbon build up) I have also used the mercury powertune product, which does the same thing, and pretty much the same procedure.
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Posted By: cosmo
Date Posted: 21 May 2013 at 9:20pm
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spoke to a good marine mech the other day and he reccomend doing it with the carb and choke cleaner as ohsoslow said,said it will smoke like bug r e and then when clears, fill carbs up with it again and leave to soak for a couple hours and then start up and again said will smoke like anything. ------------- i just want to go fishing..........amd ignore all my adult problems |
Posted By: Ohsoslow
Date Posted: 23 May 2013 at 5:12pm
| Oh yeah, sorry, I may have forgotten to mention that part.. smokes like all hell! If the neighbours don't call the fire service I'll be surprised! :P |
Posted By: Grim Reefer
Date Posted: 23 May 2013 at 5:20pm
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I've got same engine pushing around Rodzilla, just clicked 200hrs, I'd recommend staying with the evinrude de carbing juice, just a splash every tank(100lt) and she's running a lot cleaner, no where near as much soot around exhaust after a run now! ------------- Previously Rodzilla, new boat new name. |
Posted By: Durban
Date Posted: 23 May 2013 at 6:48pm
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a decarb is very important on any 2 stroke this done on a regular basis will prevent the rings car-boning up in the ring grooves when this starts to happen & the rings are not moving freely & get stuck in the ring grooves this is when piston shave starts taking place & it wont be long before you end up with major damages |
Posted By: cosmo
Date Posted: 28 May 2013 at 5:46pm
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i also add moreys upper cylinder lube (30 mls to a standard tote tank) ------------- i just want to go fishing..........amd ignore all my adult problems |
Posted By: pjc
Date Posted: 28 May 2013 at 6:41pm
| asked my outboard guru about de carb,why you are running 98 arent you |
Posted By: riga
Date Posted: 21 Jun 2013 at 8:38am
| Anyone know where to buy this stuff? |
Posted By: RC1
Date Posted: 21 Jun 2013 at 8:46am
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riga wrote:Posted By: Captn Phil
Date Posted: 22 Jun 2013 at 9:58am
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Essential part of regular servicing in my opinion. I do it every 200 hrs Ive always used the Yamaha decarb which comes in a spray can. Just spray into intakes then leave it for up to an hour, run the engine up and job done. The engine needs to be at operating temp when its done and then run under increasing load to finish. You can't do that on the hard so I do mine on the water tied to the wharf. 2500 hrs on the engine and I did compressions last week and they are all within 2PSI of each other. That confirms the importance of decarbing regularly to me. ------------- Taking sportfishing charters to the next level. Blue Water Adventures Ltd Whangaroa / Bay of Islands |
Posted By: Jet_ski_fisher
Date Posted: 22 Jun 2013 at 10:12am
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When we did the old 2 stroke. it was put out of gear, revved up a little then added the carb cleaner, it wanted to die so upped the throttle a bit and man did it smoke like hell...ran it for a 5 minutes and stopped and left it for 2 hours, came back and started it up and it smoked again, but settled down took it for a spin and all good :) ------------- http://www.legasea.co.nz" rel="nofollow">  MH... Catch measure release...<*))))< |
Posted By: Durban
Date Posted: 27 Jun 2013 at 9:44pm
| Industrial paint remover works too for de carbing |