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Author Topic:   Piston Carbon
mustang7nh posted 12-20-2002 12:31 PM ET (US)   Profile for mustang7nh   Send Email to mustang7nh  
I have a 1988 Johnson 200. When I pull the plugs and look in the cylinder with a flashlight I can see the tops of the pistons. Some are mostly shiny silver and other are mostly black (I assume carbon). Will engine tuner take care of this or am I looking at impending doom. I put 100 hours on it this summer and used carbon guard half the time (the other half I just didn't have any with me and needed fuel). I have not done engine tuner yet.


OutrageMan posted 12-20-2002 12:35 PM ET (US)     Profile for OutrageMan  Send Email to OutrageMan     
Try running a tank of Ringfree using a shock dose (as per directions on the container). If it is carbon build up, you may see an increase in your idle RPM.


mustang7nh posted 12-20-2002 07:43 PM ET (US)     Profile for mustang7nh  Send Email to mustang7nh     
Its funny that you mention idle speed. The boat idles very well in 40 degree weather in my drive way. But when its summer time it tends to stall when shifted into neutral. Not every time but 1 out of 3. Both when shifting into neutral and when coming out of neutral into forward or reverse. If you don't get in the gas quick and then back it down (goose it)then it tends to stall. It will spark right back up with a twist of the key. Ironically, other than that, the old gal runs like new.
Dick E posted 12-20-2002 09:07 PM ET (US)     Profile for Dick E  Send Email to Dick E     
That black stuff is carbon.
Engine tuner should be run thru at least Once a season or every 50-100 hours which ever comes first. Read the instruction on the can.
I word of caution if has not been done in a couple years and there is heavy build a piece (carbon)can come off a get caught on your rings and cause trouble. It happen to a friend.
OutrageMan posted 12-21-2002 12:45 AM ET (US)     Profile for OutrageMan  Send Email to OutrageMan     
Another thing worth mentioning is that the engine may run rough and spit a lot of black crud duing the first shock treatment. Dont worry about it, as things clean up, it will go away. Running it at high rpm will hap get the junk out.


weekendwarrior posted 12-21-2002 09:58 AM ET (US)     Profile for weekendwarrior  Send Email to weekendwarrior     
When the weather gets warmer then it will run richer if you don't adjust the jetting (fuel/air screw). That's probably why it idles OK in the cold and not so OK in the summer.

I've been out of the 2-stroke outboard scene for some years now, does anyone decarbonize by removing the heads and manually cleaning the carbon any more?

Jiles posted 12-21-2002 11:57 AM ET (US)     Profile for Jiles    
I don't intend to get a war started, but here is MY OPINION. I have worked on and rebuilt all types of engines, from diesel to string trimmers, over the last fourty years. I, personally, do not use "decarbon" products, I would always pull the head, if possible to "decarbon". My point of reasoning is that loose carbon particles can lodge to the top piston ring. This could cause greater damage then the problems of excessive carbon build-up. This problem of "loose carbon particles" is also present when removing the head. I always clean the top of the piston with the piston at top dead center. Before bringing the piston to T.D.C., I oil down the top one inch or so of the cylinder wall to catch all the carbon possible. I have found that after a thorough cleaning, it is best to use fine sandpaper and POLISH the top of the piston. This greatly helps to prevent future carbon deposits. It is also helpful to run the motor at a high r.p.m. after any low r.p.m. operation when possible, to prevent some of the carbon buildup. I am aware that some people are not comfortable with removing the head of a motor, and in that case I would recommend chemical decarbon and follow the directions to the letter.
SSCH posted 12-22-2002 08:03 AM ET (US)     Profile for SSCH  Send Email to SSCH     

I'm with you to an extent. I believe that you should always run decarbonizing chemicals in two cycle engines to avoid build up in the first place. Once you have a lot of carbon, I think mechanical cleaning is best.

TCW 3 oil and something like Ring Free in the gas and you won't ever see that serious carbon build up.

mustang7nh posted 01-06-2003 12:22 PM ET (US)     Profile for mustang7nh  Send Email to mustang7nh     
Any recommendations of where to get carbon guard fuel additives (brand and how to get)?


witsendfl posted 01-06-2003 02:47 PM ET (US)     Profile for witsendfl  Send Email to witsendfl     
Another great product is SEAFOAM. Only available at NAPA. Comes as an aersol and liquid gas additive. Last idea is to run AMOCO white 93 Octane gas

Hope this helps


Bigshot posted 01-06-2003 03:31 PM ET (US)     Profile for Bigshot  Send Email to Bigshot guys missed the part where he said "Some are mostly shiny silver and other are mostly black (I assume carbon)". Now I don't know about you guys but the last time I looked in an outboard sparkplug hole and saw a shiny silver piston....she was ingesting water or brand new. All 2 strokes have slightly black piston tops, silver is too clean. Just my $0.02.

What do the plugs look like for each cylinder? Are some REALLY clean and others normal or dirty?

Bigshot posted 01-06-2003 03:32 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
a VERY fine spray of water will clean the snot out of a cylinder and piston. That may also explain his stalling issues. I would investigate further.
Sal DiMercurio posted 01-07-2003 12:30 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Bigshot is right, shiny piston tops means water in the cylinders.
When using Engine Tuner [ by OMC aka Bombardier ] the hard carbon builtup behind the rings, & tops of pistons & heads, is turned into liquid, thus getting either burned or blown out through the exhaust.
Yamaha makes "Ringfree" & Merc makes "Powertune".
Seafoam is sold in most auto supply stores, not just NAPA.
I find Seafoam to work faster then the others, but be carefull when doing injected engines, as it wants to make the engine over rev when restarting after flooding the cylinders with it.
The best method is.
If you have a carbed engine, spray it into the carbs at idle, every single one of em, then flood the engine out with the liquid, then remove the spark plugs & either pore or spray it into each cylinder, while turning the flywheel by hand, let it sit overnight.
Beg borrow or steeal an air compressor & blow the excess liquid "OUT' of the cylinders, replace the plugs & fire her up.
The smoke could bring a fire engine, but it gos away after about 5 minutes.
Put the boat in the water & take her for a ride until she runs clean, at least 15 minutes.
Then replace the plugs, as they will be filthy.
Use decarbon "EVERY" 50 hours or your gonna be in trouble down the road.
Guaranteed your engine will run & be much happier then if you don't use it.
mustang7nh posted 01-07-2003 08:14 PM ET (US)     Profile for mustang7nh  Send Email to mustang7nh     
I put engine tuner in it while sitting on the trailer. I have power steering and cannot get the air cleaner box off to get at the carbs because of the hydraulic hose mountings. Hence, I pulled each plug, sprayed about 5 seconds or so of engine tuner into each cylinder and turned the flywheel by hand. I let it sit overnight. Then started it with the earmuffs in the driveway and let it run for fifteen or twenty minutes at various rpm. At this point in time it was not only cold but I didn't get home from work until dark and was away weekends so I couldn't splash her to really run it hard. I felt this would be better than nothing as someone told me that carbon hardens and it could be worse if I let it sit over the winter.

She starts fine, idles fine (in cold weather) and no more smoke. Now when I pulled the plugs to put in fogging oil I noticed the some silver some black on top of pistons. I put a solid dose of fog in each cylinder, put new plugs in, took of kill swith, left plug wires off and turned if over for two seconds. Now she sits for the winter.

Does this change the consensus about the water possibly being in the cylinders? The old plugs from this summer were somewhat gummed up with carbon. I don't have a good reference but I would say a medium amount but they still ran it well so they fired in that sense. I didn't pay enough attention to compare each plug but none jumped out at me as terribly different from the others.

I do have one spark plug (the bottom one on the port side that gets rusty on the outside.

Bigshot posted 01-08-2003 09:40 AM ET (US)     Profile for Bigshot  Send Email to Bigshot should be ok. Install new plugs after the initial 1st day. Put another 10 hours on it in the spring and check the plugs again.

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