87 Merc Force 125HP - Can't get to WOT

[Leftside34]

Bought this boat/engine last year and have gone through a lot of troubleshooting and replaced some items. Seems like I keep getting caught in the rabbit hole.

Replaced CD Module, Plugs, Fuel Filter, adjusted the CAM and throttle linkage along with the Choke. After I've go through all of this it sounds great in the driveway with the muffs on. My tach isn't working and I replaced the rectifier but that did not solve the tach issue. Still thinking about that one, so any advice would be great.
Did compression test and all looked good.

In water I can only hit 10 mph at WOT, when investigating my CAM it's not fully rotated on the eccentric cam but I can move the CAM manually forward and the inner Carb. throttle valves will go fully horizontal or wide open with throttle link disconnected. I've gone through the book and adjusted the CAM roller to the eccentric CAM and trigger linkage as it's shown. The problem is the throttle link arm is fully extended, although it does get closer to WOT but still not all the way. It also sounds like when I do this and return to nuetral the RPM's sound very high. Unfortunately my Tach isn't working so I'm not 100% where I'm at in that regard.

I can't seem to understand what is not quite set correctly so a few questions:
IF the timing is out would that affect getting to WOT on the water.
Would the Throttle cable to the helm affect WOT? Can these be adjust and/or should they be?
A wore out or bad Remote at the helm affect WOT? The mechanic's, arm, plastic cam inside, can they affect my WOT.

The main thing is I'm not getting to WOT with the muffs on in my driveway once all is set per the book, other then the Timing as that's the next on my hit list.
Thanks for any advice anyone has on this, getting stumped and might need to take it to a mechanic if the timing tower adjustment doesn't do it.

It's on a 87 Bayliner Bass Striker 18'.

 

[tednv]

I had a similar problem with 90 force, check timing, check magnets under flywheel to make sure none moved or are cracked. Also try unplugging one spark plug at a time at low rpm to make sure each cylinder is firing. If it's not firing and everything else is good, it's probably the coil pack. I had a hard time with the carbs too on that one, it used a separate carb for each cylinder and had to make sure each one was clean and working right (rebuilt)

 

[Leftside34]

Thanks Tednv, I'm going to check timing tomorrow evening but will inspect the magnets tonight. I replaced two coils last year but will check all again. I believe I will need to rebuild them, never did that before but time to learn!

 

[tednv]

with those magnets, you have to be really careful they break off real easy sometimes when you're taking off the flywheel. what you can do is without taking it off, go underneath the wheel with your finger and go around the entire thing and feel if any are moving. don't push on them hard, just try to feel it out and see if any feel out of place or crooked. They will still stick to the flywheel since it's steel, but if they're crooked because the glue came off, it won't fire right. Removing flywheel is kind of a pain too because you have to align (and try not to break) the little key, but if you have any that have moved or are broken might be able to feel them underneath. if its just loose and not broken you can glue it back in place using epoxy if it's broken will probably need a new flywheel, they're expensive though. or sometimes there are posts with people selling their old magnets too, but hoping none of yours are broken. if you're serious about rebuilding it you should get a clymer manual for the engine, it has a lot of really good troubleshooting info tells you resistances of ignition components so you can check them all with ohmmeter

 

[tednv]

also don't rev it up too high on earmuffs in the driveway and you definitely shouldn't be trying to WOT it out of the water. you should be able to tell if it's not running right without having to rev it up real high by just giving it a few brief pumps

 

[jerryjerry05]

He doesn't have that type of flywheel.
That type was used on Forces made after 92-3
​His has a magnetic strip that circles the inside of the flywheel.
His also has 2 tiny magnets in the center of the flywheel next to the hole.
​The strip sometimes comes unglued and sticks to the stator.
​It wouldn't start if the magnet was loose.

Without a tack your just guessing.
They sell a thing called a Tiny Tach.
I bought one for 16$ Amazon.

When in the water and going 10mph does the motor sound like it's revving up?
That shows the hub in the prop is spun.

​What are the compression readings??
You do a spark test?

Check for water in the fuel?

​The flappers in the carb don't have to be level to get wide open throttle.

One of the top posts is a post covering a procedure called a link and sinc.
​Do this.

​Post the results to my questions.

 

[NEKFORCE]

Check the carb / timing advance linkage. I saw this happen to a 1989 125 when the nut vibrated loose and came off.