Dirty pistons....fuel opinions?

[elwopo]

I have a 96 Force 120 with 40 hours on it. Had some problems and was advised to "decarb". Not sure exactly what that means...but I tilted motor up fully, removed plugs, divided 1 can of "decarb" spray into 4 cylinders and let sit overnight. Ran in the morning and did same thing again. Each morning there was not much liquid in cylinders as it seems the fluid just leaked past and went somewhere. <br /><br />This "decarb" spray way 10.50 per spray can. Is it any different than cheap carb cleaner?<br /><br />Piston tops are still black and have 'caked' residue on them.<br />Is this normal or something I should address until it is 'fixed'? I'm not sure pistons should be this dirty....but I don't know.<br /><br />What are your opinions on fuel? Should I use reg uleaded or does 'super' make a real difference?

 

[rodbolt]

Re: Dirty pistons....fuel opinions?

most likly the fluid ran out the intake or exhaust ports. rings have endgaps and wont seal liquids long. most decarb sprays are done with the engine running. with 40 hours I doubt you have a carbon problem. you actually want a small amount of carbon on the piston, works better that way. its when it build up so much as to interfere with the piston to head clearence or cakes the ring grooves that the problems start. my advice would be to use the merc equivalent of yamahas ring free at the prescribed ratio, usually an ounce to 10 or 15 gallons of gas, and go enjoy the boat. unless you have a mechanical issue.

 

[WillyBWright]

Re: Dirty pistons....fuel opinions?

If all else fails, read the instructions on the back of the can. You need the heat of combustion to get things going.

 

[TimMattson]

Re: Dirty pistons....fuel opinions?

Willy nailed it,<br /> We use Carbon Guard, Engine Tuner ,or whatever each co. calls it....Spray it into each carb while running AND warm.Let sit 15 minutes and NO MORE.....then run it hard to blow out all of that ring killing muck.Fresh plugs every 50 hrs and after each carbon treatment.Cheap oil and gas will bring on the carbon.Use TCW 3-4.<br /> Tim m