1998 125HP loss of power

[diegome]

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On a force 125hp I can't get the boat to go past 2500 rpm and 6 to 8 kts.
we have checked carbs and the mech say they are ok, next he checked fuel pump and ok next checked current and plugs and ok next checked for proper propeller size and ok,then checked compression and got 140psi on 3 cyliders and 136 on 4th, then checked head gasket and ok but when checked head gasket there's a little play in the pistons and the mechanic says that is the problem, I need new piston rings
but someone else told me that new rings wouldn't bring the wot rpm's to 5200
please any advice.
Thank you

 

[bowhuntrrl]

Re: 1998 125HP loss of power

The compression tells you that your rings are fine. It is more likely fuel or carb problems.

 

[roscoe]

Re: 1998 125HP loss of power

Compression looks good.
That leaves fuel delivery and spark.

In my opinion, the "mechanic" either does not know what he is doing, or is taking you for a ride.

Find a new mechanic.

There was absolutely no reason to pull the head and check the gasket or the rings, if the compression readings are as you say.

 

[MikDee]

Re: 1998 125HP loss of power

I agree completely, one item you might want to check is make sure your linkage for the spark advance is working properly to give you full spark advance at full throttle. You can usually visually check this with the motor off, just make sure it is hitting the stop point, at WOT. I had run into this problem once before. Aside from that, I'd check anything related to fuel delivery, and venting of the fuel tank.

 

[diegome]

Re: 1998 125HP loss of power

Thank You Roscoe
The mechanic was looking for the possibility of bad head gasket that will make compression escape from one cylinder to another and that's when he showed me that the pistos have play in the chamber and said that the rings are worn. hw checked the spark advance at wot and it goes all the way to the stop, he also checked for fuel problems (fuel tank vent,fuel lines,filter,water separator,cutoff valve,etc) he even run the boat with aportable fuel tank with fresh new gas, he suspected that the ignition system from the 1988 was a possibility and he went ahead and replaced it with one that I had on my blown 1991 120HP and all of this done in front of me, we still having the same problem.

 

[diegome]

Re: 1998 125HP loss of power

thnk you all

 

[MikDee]

Re: 1998 125HP loss of power

Did you get it fixed? 3 more items that I would check, 1) make sure you have all the spark plug wires, on the right spark plugs. 2) make sure you have the right spark plug number, and replace them with new ones. 3) if this don't work, I'd start checking for bad reed valves, after this, I'm plum outta ideas for the moment???

 

[diegome]

Re: 1998 125HP loss of power

Thank You Mik Dee
we have checked all of that and the machanic is in the process of putting new piston rings, will see what happens in a day or two, I paid for the parts but I will not pay for the labor if it doesn't work.
I'm still open to any other suggestions.
I'm trying to save this season or I will have to put in storage till have for a replacement engine, but sounds like were overlooking something or somewhere,
this engine sounds very good to have to replace.
Thanks.
Diego

 

[MikDee]

Re: 1998 125HP loss of power

If your compression was good, you shouldn't need new rings? I still think you may have a couple spark plug wire crossed, I've seen this happen before, with similar results.