Help with running a motor that's sat for 4 years

[Hookmaster]

I have a 1985 25hp Johnson motor that hasn't been run in 4 years. It was winterized before this long hiatus. I plan to use it this fall. What are the steps to best ensure that I can get it running? I have never decarbonized this motor, is this something I should include in the process?

[Surface Tension]

At the time that outboard was made the recommend oil/gas ratio was 100:1. Thats been revised to 50:1.

Heres what I'd do if it were mine. Change the impeller, new spark plugs and drain and replace the gear oil.

After running it you may find out she runs like a top and all you need to do is the normal maintenance. Or you might find out the carb is dirty and it'll need to be cleaned and the lower unit is leaking oil or water into the oil.

[IFallsRon]

I'd spray some oil into the cylinders to ensure you have lubrication and compression.

[eurolarva]

Wait to do the decarb and new plugs until motor is running good. It will be one less concern if motor gives you any grief on start up. I would run the first couple gallons of gas 24 to 1 like a new motor break in then go to 50 to 1. When you do the decarb Seafoam Deep Creep in a spray can is awsome stuff. After you decarb then put on new plugs.

[Hookmaster]

I got it running on the muffs yesterday. I flooded it which usually doesn't happen. I almost gave up but after about 25 pulls (I got my workout in), she fired up and ran great. I'll get it on the lake some night this week. Anybody have a recipe for decarbonizing or shouldn't I even do it if it is running well?

[countryboy9799]

If it run's well I would leave it alone. Sometimes messing around will get yourself in more trouble. Unless you know there is a problem.

[eurolarva]

Run it a couple of outings to verify it is running good. Buy a can of seafoam deep creep and warm the motor up. With cowling off slowly keep spraying the deep creep in till motor starts to stall and quit spraying till rpms come up. Keep doin g this till about 1/4 can is sprayed in. Then take the plugs out and nuke them with deep creep and put the plugs back in. Wait over night or a couple of hours then run the motor hard till it quits smoking. Plan on replacing plugs afterwards.

[Hookmaster]

I ran it last night. It was like it was never in storage. I'll change the lower unit lube and put in new plugs and away I go.

[iffwalleyes]

The older Johnsons were a pretty dependable motor. Seems like you could abuse them much more than the newer motors. My dad had a 9.5 HP Johnson that hadn't been started for about 6 years till this spring. Dad told me I bet it will start in 2 pulls. I said no way I will have to do a carb job and all kinds of stuff to it but I decided to try starting it first. It fired off on 3 pulls. Idled a little rough so I added some OMC engine tune and new plugs and it runs a good as it ever did. I had to call dad and say you know you were way off it took 3 pulls not 2 .

[lawdog]

congrats you are lucky.

I'd still run a can of sea-foam through the first tank of gas to help clean it up a bit and you better just watch it so no gunk gets loose and bogs it down for a while...

[Hookmaster]

Seafoam's already in it!