odd issue with Merc Force 120

[Beno]

Still not getting full power out of the this 93-95ish Force 120..  It starts instantly, it Idles well.. But has a little kick every little bit.. Extremely constant  but hardly detectable kick
Runs well.. but them when get open it up.. starts falling apart.. rpm wavering at higher rpm.. can’t get to proper highest rpm.. Feels weak.

I’ve replaced the carbs (with used carbs from a 1989 125.. for testing .. seems they both use fuel jet# FO16133 and bolt directly up)
The trigger has 280k ohms to ground on all 4 colors (Blue, Brown,white,purple)
The stator WGreen and GWhite ohm test perfect
All 4 (825207a2) coils test out according to online Capacitor discharge module testing specs
Compression test solid 125+ on all cylinders
Visual spark confirmed on top cyl (so far)..
To me this pretty much rules out Spark issue or compression Issue and carbs as a issue.. (not much left?!)

The most important clues I have so far..
Testing in the driveway at idle under no-load.. I can disable the coil on cyl 1 or 2 and it does *not* change the idle rpm at all… disabling cyl 3 almost kills the engine at idle and disabling coil 4 just drops the rpm a bit.
Spark on #1 looks solid at idle rpm (I have visual spark tester thingie)
After a 30sec of running the bottom 2 cyls are warm at the spark plug.. the top cyls feel considerably cooler.

Any ideas? I’m still researching this.  I’m closing in on it tho!
I’m targeting ReedValves as my #1 suspect..  they’re a bugger to get the gaskets off on this model tho.
I also plan to try the propane torch trick (add propane to each carb when running (enriching) to see if it changes the backfiring or engine performance)

 

 

[crosbyman]

deletd

 

Joining AOMCI has priviledges 🙂

[Beno]

I’m going to re-test compression, just to rule out any problems I might have missed.

I believe I have trigger #827509 can someone familiar with trigger testing look over https://www.go2marine.com/Product-Guides/MFR/CDI/Mercury-DVA.pdf
scroll down to where it gets to 80-125 CDM 4 CYL 1995-2006  then over to the right for the trigger testing:
it says “Engine Gnd toBrown, White, Purple and White/Black” for values it says “OPEN”. (other online sources say “not applicable”?)
(why have directions as to how to test it, then say testing it not applicable?)

I’m getting 266-288kohms on ground to each color…   could they all 4 be bad.. and bad in the same way?

 

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