120hp force

[HighTrim]

Hey Gents,

First time over here from the Johnny/Rude forum.

Recently aquired a 120 HP Force, US Marine version.

Im thinking '93, but would have to verify, cannot remember off hand. Motor is up north.

Do these like the NGK plugs or the Champs? I run Champs in all my OMC motors, but new to the Force motors. Im assuming my options are the NGKBUHX or the Champ UL18V?

Is the testing procedure similar to OMC for testing the Rectifier? My tach only gets up to 400 RPMS, have not actually determined that the tach is not faulty yet, but want to cover everything.

Should I be about 5400 RPMS or so at WOT?

 

[Frank Acampora]

Re: 120hp force

BUHW or BUHX, UL18V or L20V, or even the Merc L76V (Merc used them in the late 90s Force engines).

5400 is a good top RPM although the engine may be rated for 5250. I don't know the exact rating for various years but most of those 4 cylinder engines were rated to run somewhere between 4500-5500.

The rectifier is tested with an ohmmeter. There should be continuity one direction only on each of the power and ground terminals and I think also on each alternator terminal to ground

 

[HighTrim]

Re: 120hp force

What is the difference between the NGK plugs?

 

[Frank Acampora]

Re: 120hp force

Both are surface gap--the only style for these engines. Very slight temperature difference. The engine should tolerate either. The only plug problems with these engines is use of a bent electrode plug. Surface gap plugs are dead cold while bent electrode are hotter and may cause melted pistons.

 

[emoney]

Re: 120hp force

My '95 runs right around 5200rpm WOT for what that's worth. Welcome to the Force side of things, btw.

 

[HighTrim]

Re: 120hp force

I ended up getting the BUHW, as my local supplier did not have the BUHX.

I dont have much experience with the surface gap plugs, do they easily foul? Foolishly decarbed the motor after I cleaned the carbs, now having idling issues, especially going into and out of gear while docking. Thought through the decarb that I foulded a plug, but thinking now I simply loosened up some crud which is restricting my low speed circuit. Will try new plugs, hopefully I dont have to pull the carbs again. Pretty simple on these motors though.