So i decided to pull the powerhead off....

[o4rudeboy]

hello everyone and thank you for reading my post . i have an 86 force 85 hp 3cyl that came with a boat i purchased the motor has tested at 90 psi in all 3 cylinders. i fished in it a few times and it ran ok once started just not much power and not reving past approx 3500 rpm. I decided to have a go at repairing it over winter. i convinced myself the rings / cylinders must be worn out after reading a bunch. i pulled the ph off and took head off , everything looked really nice . then i went and pulled the intake side off and split the case and removed the rods and pistons. they looked mint but there was thick carbon build up on the rings and the rings were all seized. i have cleaned them off so they now move freely but im unsure if i should just reassemble and hope for the best or what ? Also my rod bearings look ok but the rollers wont seat in the cage is that normal or does that mean they are worn out. how do i determin if they are good to reuse. i would love to reassemble and get two seasons out of this motor anything more would be a gift if anyone has any tips or info for me please let me know its waring up and i want to be ready to fish thank you

 

[racerone]

Correct many bearings on outboards have loose rollers.-----I assemble them with needle bearing assembly grease.

 

[jerryjerry05]

Like racerone said use "bearing assembly grease" on the loose bearings and make REAL sure they stay in place.
One falls out and the rebuild is done.
Can do serious damage to a cylinder if it falls into it.
Has the motor been rebuilt before? check the pistons for marks on top of the piston?
Reusing the rings?? it's been done(my own motor) and the results lasted for years 15+.
My motor had less than 50hrs. and the rings carboned(lots of slow trolling).

Just make sure the port cover gaskets get sealer and cures before starting.

 

[Sea Rider]

And re-torque all bolts that have been previously removed on the entire powerhead to their factory specs soon after the motor's first 10 run hours upon full restoration. Personally would install new piston rings on all 3 cylinders. If reusing piston's rings each one must be reinstalled exactly in its respective groove from where it was originally removed...

Happy Boating​

 

[o4rudeboy]

omg this is very good news thank you all i will be starting reassembly today and yes evything looks original the boat sat for a long time i have no clue what the hours are but everything internally was very clean with no indicators of heavy wear or friction only the carbon build up around the ring gaps

 

[Sea Rider]

Proper time to install an induction hour meter inside the motor to check run hours upon full restoration...

Happy Boating​

 

[o4rudeboy]

good idea i will def do that hour meters are awesome . are the cheap ebay ones good on boats ? i put one on a dirt bike i had back in the day . another issue i brought motor to machine shop and my piston is 3.302 and my cylinder is 3.314 i wanted to rehone and reassemble but he suggested that pistons are too worn to reuse im not sure what my options are do i just reassemble and hope it doesnt slap too much or buy stock pistons and rings if i can find them .

 

[racerone]

Standard bore is 3.312"-----You need new pistons !!-----Fix it once and fix it right.

 

[Nordin]

If the cylinder walls are good just put new std piston with new rings in and hone the bore.
As racerone says the std bore from factory is 3,312 in.
You will find pistons and rings from different web sites such as this one, Master tech Marine and a lot of others.
Best source in my opinion is Franz Marine, he will have OEM or aftermarket pistons if available, not cheapest BUT really service minded and you will get the right stuff.

 

[o4rudeboy]

If the cylinder walls are good just put new std piston with new rings in and hone the bore.
As racerone says the std bore from factory is 3,312 in.
You will find pistons and rings from different web sites such as this one, Master tech Marine and a lot of others.
Best source in my opinion is Franz Marine, he will have OEM or aftermarket pistons if available, not cheapest BUT really service minded and you will get the right stuff.

ok i will pull the trigger on new pistons and rings soon as i hear back from the machine shop im learning a lot thank you guys for being so helpful i just hope i dont screw this thing up wish me luck

 

[jerryjerry05]

The older pistons need a special tool to reassemble them.
Post pics of the pistons,

 

[o4rudeboy]

does anyone know what the measurment of the standard piston was when new im tripping out now and worried my cylinders are too big i went and picked up my block and it was honed to 3.315/6 and i ordered stock rings and pistons thinking he was going to be able to keep it at 3.314 am i screwed ?
heres the old piston they all are worn to 3.002 or under

 

[o4rudeboy]

my thinking is that it didnt have any piston slap and ran ok when it was loose with the stuck rings it should be fine with new pistons and rings going in a freshly honed cylinder but i also know very little about how much is too much and we are splitting hairs with these clearances

 

[racerone]

When you post the diameter of the piston you need to be VERY clear on where the measurement was taken.------Even a new piston is tapered !------So a diagram of where you measured may help you.----Piston size is measured !/4" from bottom of skirt.

 

[Nordin]

As racerone says the piston is tapered.
Factory manual spec for a new std. piston has two different measure at two different part of the piston.
Piston top just under the lower ring.
MAJ. Major diameter measured 90 dgr to piston center line ... 3,3003-3,2993.
MIN. Minor diameter measured on piston pin center line ... 3,2963-3,2953.
Piston bottom about 1/4 in up from skirt end.
MAJ. 3,309-3,308.
MIN. 3,305-3,304.

 

[jerryjerry05]

That piston didn't look that bad.
Pics on both side on all 3 pistons?

 

[racerone]

You need to DECLARE where your measurements were taken.-----Even a new piston is tapered.

 

[o4rudeboy]

thank you all for the tips . i went ahead and ordered new pistons i finally am reassembling it now my old pistons looked good and had no major scoring on them but the machinist knows best , i hope it works out i will know in a few days it was annoying trying to measure it accurately with my little caliper this is my first outboard rebuild.

 

[o4rudeboy]

update my motor ran ok the 3 times i took her out but then i started having running issues related to spark and fuel missed all of last season and am trying to get it right now once again .

 

[o4rudeboy]

so i lost spark on cylinder 3 and started reading i even bought a manual and a multimeter .i confirmed my stater was bad with an ohm test and bent over and bought a new one. i put the new one on but i then received less spark on 1, great fat arc on 2 and minimal spark on 3. i almost cried, i spent over 300 on the part and it didnt fix it , i just want to fish man .....i swapped the hot cdi wire from the number two coil to the 1 and 3 cylinders coils both fired great confirming coils are good (i think ?) then i took the cdi boxes off and swapped them hooked everything back up and the same condition is present weak barely visible spark on 1,3 fat orange one on 2 i ohmed the trigger and they are all at 48 ohms what could it be im not very experienced with electrical troubleshooting but im enjoying figuring this out please help