1998 Force 120 compression and spark plugs?

[billglynnn]

Hi, I am going to look at a 1998 Force 120 that is on a Trophy 1903 of the same year. I need to know what the compression readings should be, and what the correct spark plugs are for this engine. I saw that some 4 cyl inline engines use a staggered compression scheme - maybe to cut vibration?
Thanks for any info!
Bill

 

[roscoe]

Re: 1998 Force 120 compression and spark plugs?

Welcome to iboats, Bill.

I believe they did use an unequal compression in the later years of that motor.
No numbers were published from the factory. Instead, they gave a range.

THe range from the factory was 143-155, or there about.
With 2 cylinders being near the top, and 2 near the bottom of that range.
Anything over 125 is decent.

Of course, warm/cold engine, throttle position, accuracy of the compression gauge, and how recently the engine was run, will all effect your particular numbers.

Good Luck.

 

[billglynnn]

Re: 1998 Force 120 compression and spark plugs?

Hey Roscoe,
Thanks for the info.....Guess that I will have to "wing it" when checking out that Force 120 this weekend - it's gonna be below freezing, so I will guess that the compression might be lower than if the engine was allowed to warm up before testing. I won't be near any running water. Might have to take the word of the dealer mechanic who tested it and winterized it in the fall. He only indicated that the compression was "good". The dealer is not the one selling the boat, so no reason for the mechanic to exagerate, I guess. The motor is claimed to have only 75 hours on it, all freshwater. It has not been run in the past 5 years, except when checked in the fall. The boat was last registered in 2002, it's a 1998, so I can believe the hours claim.
I will pull the plugs and do a check just to see what it actually reads. Are there any other items that you know of that should be checked out on this motor before purchasing the boat?
Thanks for your help
Bill

 

[roscoe]

Re: 1998 Force 120 compression and spark plugs?

Plan on spending a few hundred to get her running well, carb rebuild, fuel pump rebuild, etc.

The tilt and trim should be checked for function, they are expensive to repair.


Spark plug should be Champion L76V, or NGK BUHW, or Autolite 2852.

If you can get a few drops of gearcase oil to drip out, it should be clean, no metal shavings, no water.

But if they really just winterized it, it will look that way anyway.

Let us know how it goes.