1985 Force 125hp piston removal

[Botard]

Hi all, new here.
I have a 17’ proline center console with a 1985 Force 125hp. I've got 0 psi compression on the bottom cylinder and after taking off the head I can see the piston is pitted and seems to have had better days.
is there any easy way to get to that piston? Or should I just tear it all down? I thought I read somewhere you can change a few of the pistons through the intake.
Looks like a pretty daunting job.
Thanks

 

[Nordin]

You can change piston through the intake side after removing the manifold and carbs.
I have done it at some 70-75Hp Chryslers, same design just one less cylinder then the 125Hp Force.
It can be a patient job but it i possible. The big thing is to collect all needles when removing the rod cap and when you going to put it back again.
There are some posts at this forum about it soo search.

 

[jerryjerry05]

The bottom one is the hardest to do like Nordin said.
What condition is the cylinder walls??
ANY grooves or scratches will just contribute to another failure
If you can catch an awl in the grooves, it needs bored out.

The good part is you can do just 1 piston and have a good runner.
I rebuilt one(actually more than one)for a guy in Va. 7 years ago and it still runs
with the one cyl. rebuild.
You do need to redo the other rings.
For that job, you should remove the block.
You'll need to take it to a machine shop for the bore and hone job.

 

[Redbarron%%]

I replaced one piston on my 90 Sport Jet and I hope that it is going to work out in the long term.
I did take the engine down and split the case since I was not sure that I could get the bottom bearing back together correctly.
My burned piston did not damage the cylinder just melted the top.

 

[Botard]

Thanks guys. I’ll give it a shot. I didn’t feel any scoring with my fingernail but I’ll inspect closer.
another question...when I’m traveling in the boat, water gets into the motor housing somehow. I guess a gasket or seal where the leg meets under the front of the motor? It sprays in when traveling.
I’ll update with the new piston

 

[jerryjerry05]

Oh yea you'll need a 12point 1/4" socket.
The water? how much and deep?
Might come in when setting as you launch?

 

[Botard]

It’s definitely not coming in at launch. When I take the cover off, as I usually do and have to fix something, water is sprayed on the bottom carb and around the bottom of the inside of cover housing. I’m guessing from the front of the motor leg it’s getting shot up. Could be the reason for my faulty piston. The pressure relief on top of the head does have a dribble more recently, but I think I just need to put a clamp on the plug cap there....getting off topic. I’ll just have to see where it comes from when I get it back on the water. Any recommendations on reed valves?

 

[jerryjerry05]

You said: The pressure relief on top of the head does have a dribble more recently, but I think I just need to put a clamp on the plug cap there..
What pressure relief?

 

[Botard]

Hmm..well I guess it was originally a plug. I just looked closer on the schematic. On my engine, on top of the head, there’s what looks like a nipple with a small section of hose to plug it. There may or may not be a zip tie involved . I’ll order the plug.

 

[Botard]

So it was rather easy to get the piston and connecting rod out....well what’s left of the piston. There’s a huge chunk out of the side. Only one ring left on it with minimal cylinder damage. Massive carbon buildup in exhaust ports. By massive I mean maybe 1/8” thick in some spots and as smooth as the cylinder wall. Question: can I hone this cylinder like any other?
I’ve attached a few pics for enjoyment.... Ordering parts now. Any recommendations on piston kit and reed valves?
thanks for the help so far!

 

[The Force power]

Hmm..well I guess it was originally a plug. I just looked closer on the schematic. On my engine, on top of the head, there’s what looks like a nipple with a small section of hose to plug it. There may or may not be a zip tie involved . I’ll order the plug.

From what you are describing I gather that is the elbow fitting for the tell tail that should have a hose attached to it long enough so it can be routed to the outside of the bottom-cowl

This should not be a dribble but a steady stream of water coming out

 

[jerryjerry05]

The fitting on the top was probably added later for
a tell tale 1/4" or 1/8" pipe plug.

The later models 95and later came with the TT and it
was attached to the cover on the thermostat.

The damage on the cylinder walls: IF?? you can catch
a fingernail on any grooves?? then it might need a bore
job. Take it to a machine shop that works on outboards.

If it's just one piston and rings, Wiseco sells something that
installs easily and not too expensive.
Or, get a good used piston/connecting rod and new rings.
I bought a piston for a 98/120 for 35$