1990 Force 120HP carbs mix adjustment help

gica

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So I set timing at 28BTDC.
I tried adjusting the mix screws by the book but when I go counter clockwise I don't really get the bogging, stalling issue to go the other way until stalling again and adjust in the middle.
So I read somewhere, maybe Jerry mentioned it somewhere don't remember, that you go out 1 1/2 and start going in 1/8 at a time until it stalls and then just turn it 1/2 turn out again.
Also the idle is it 750 in gear or neutral? Thanks guys.
 

jerryjerry05

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750-800 in gear.

Trouble setting idle: start the motor, spray starting fluid around the intake side of the motor. Under the coils/packs and the base of the carbs.
If that makes a difference? then it's sucking air and the gaskets need to be replaced.
 

gica

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750-800 in gear.

Trouble setting idle: start the motor, spray starting fluid around the intake side of the motor. Under the coils/packs and the base of the carbs.
If that makes a difference? then it's sucking air and the gaskets need to be replaced.
Thanks Jerry the motor is fully rebuilt and it now idles fine after changing stator. My question is on the air mix screw adjustment.
 

jerryjerry05

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If it's idling ok?? Then why adjust the air screws?
Doing the test with starting fluid will insure the air screws are set right.

Setting the screws: turn in till they bottom out(GENTLY) then out 1 and 1/8th turn.
If the motor idles good then ??? Leave it there.
Test: Run the motor at wide open for a few minutes, Then turn the key off, don't throttle down, just turn the motor off. Then inspect the plugs for proper burn. They look ok? Then leave it there.
Still do the starting fluid test. One port cover gasket that's leaking can cost you another rebuild( I know)
 

gica

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I definetly will test. The carbs were disassembled and cleaned so I wanted to adjust the screw for mixture. Don't want to run lean 1 and 1/8 sounds great.
Can you elaborate on the spark plugs as far as what to look for in the color or build up. They are new plugs and they are thw flat ones.
 

gica

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Plugs: all 4 burn the same color.
Ok I took the boat out yesterday and of course the rebuilt engine was giving me issues to stay at idle while in gear. So, I readjusted the pivot throttle cam to touch the roller perfect. But then I still didn't get idle in gear so I had to adjust the throttle link bar to extend it so it can push the pivot cam farther into the roller when connected to the tower shaft. I also adjusted that engine closer to 1 &1/2 to get the carbs to not bog down when throttle was turned on. With the idle also adjusted up a lot from halfway it is now holding idle but I don't like it, don't think it is right. Remember this is a twin-engine Force 120 and if you only run one you get up to 10mph maybe. So, with both engines compensating each other I was able to get to 36Mph and 4100RPM???? showing on the good engine tach. The rebuilt one doesn't send a signal to the tachometer, so I have to check the grey wire or change the rectifier if it is not sending the pulse.
The timing is at 28BTDC, and it is what the manuals show to put it at, but the linkages and the throttle link are not adjusted right in my opinion. The linkage for the rebuilt engine remote control is way off. If I put it in reverse, it goes but I get no throttle and it sometimes dies. I have to redo the linkage from the gear shift rod, interlock lever and upper shift rod, and then the cables. I have managed to get the actual manual from my year 1990 but they don't do dual engine adjustments.
Can the timing be off based on the linkages adjustments being off? Can this affect idle in and out of gear and cause it to die. Also, the RPM is below the 4500-5000 WOT that the book mentions. So, both engines need to be adjusted right to reach that.
One time the alarm for the rebuilt engine went off from heating up at really low speed, and I did notice the nipple didn't spit any water. I let it cool down and it was fine after that. But the idle and adjustments are the problem. So, I have a new stator and trigger and a different good-looking flywheel, the modules and coils were tested on the second engine, and the 2 carbs are from the second engine where they worked fine. Compression is at 120-125 on the rebuilt engine and I didn't really get a chance to break it in because of the idle in gear issues.
Let me know if you have anything to point out. Thanks in advance.

Hey Jerry I found an old post about adjustment of the shifter. Is it valid for the 1990 Force 120? Do you still have the manual pics?

In the post the OP mentioned that the issue with the linkages made the motor die. I assume that it could also cause it to die in gear and not get proper idle adjustment and timing?
 
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gica

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So in the 1990 96, 90, 120, 125 book they mention to screw the shaft in all the way and back out 4 turns. I wonder, are those 4 complete 360 turns or would 180 be considered a turn? My problem engine was out half a turn so completely bad. The other good engine is out 2 full and a half.
 

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gica

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Ok I think I got it. I did 3 1/2 out for the lower gear shaft. I Set the interlock shaft and towershaft arm at the same height and in neutral by playing with the 2 nuts. I adjusted the neutral switch cam to the switch button. Adjusted the eccentric roller for idle and the throttle link shaft at WOT. I have to recheck timing to je at 28BTDC again. And see if I get more room for idle adjustment in the water. Plus maybe readjust tye air mix if needed. I hope this does it. That new book I got has all this stuff in it. The 92 and and Clymer did not mention some stuff If you guys have anything to add let me know.
 

gica

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I redid the timing it was at 29 so put it back to 28. RPM on the hose is at 1100. I have a lot of room to raise it now. The other day on the lake I had it up almost all the way to hold idle in gear. I hope this makes a difference in the water. It sounds way better on the hose then before. I really understand how it all works now from the gear rod to the remote control and trigger timing they are all intertwined.
And since a computer doesn't adjust it for you you have to do it manually.
I lowered the mix screws to 1 1/4 I know that below 1 is not good since it is lean and can cause frozen pistons at some point. But I wonder how high up towards 1 1/ 2 is safe to go?
 
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Nordin

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I would say every adjustment more than 1 turn out of seated are acceptable.
But of course not to much as too rich adjustment will foul the plugs.
Leaner adjustment... better idle, BUT too lean the respons when doing a "hole shot" will end up with it hesitate or die.
Some Chrysler/Force engines will have up to 2 turns to work well but that is the limit in my opinion from my experience.
Most important things are.
Right timing (28-30 dgr BTDC at WOT).
Clean carbs.
Proper adjusted carbs (air/fuel mixture setting and throttle pick up point)
Good quality TCW3 oil.
Then do not run the hell out of the engines, run at varios RPMs and not at WOT all the time.
 

gica

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Have a question the 120hp original rectifier is FORCE#F369450-1. That's 120 bucks. On mine the second 120 has a
815279T Regulator Rectifier https://a.co/d/50I0yTb and it works fine.
I used a similar one on the other but only one red wire https://a.co/d/iinhc3w
My question is if there is a difference between the styles. The original is really expensive at 120.
 

gica

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Ok so the 120 from 1990 has a 7A charging system and the original rectifiers would dumping voltage to ground above a certain number of volts.
So my questions is can I use the square rectifier with 4 or 5 wires(2x yellow, 2 or 1x red, grey and with or without black) I think those are for the 16A ones. I don't see the problem. Let me know please and thanks.
 

Nordin

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I have never change a rectifier/regulator but I think you can used both if both can manage the charging amperage from the stator.
If your stator output amperage is 16A use one that manage at least 16A or more, if the output amperage is 7A choose one of them.
I am a senior electrician/electronic technician and that what I am doing for living.
They have a bit different wiring as the 815279T has a separat grounding wire and the 230-22110 is grounding through the housing.
230-22110 has one DC+ wires, the 815279T has two.
 

gica

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I would say every adjustment more than 1 turn out of seated are acceptable.
But of course not to much as too rich adjustment will foul the plugs.
Leaner adjustment... better idle, BUT too lean the respons when doing a "hole shot" will end up with it hesitate or die.
Some Chrysler/Force engines will have up to 2 turns to work well but that is the limit in my opinion from my experience.
Most important things are.
Right timing (28-30 dgr BTDC at WOT).
Clean carbs.
Proper adjusted carbs (air/fuel mixture setting and throttle pick up point)
Good quality TCW3 oil.
Then do not run the hell out of the engines, run at varios RPMs and not at WOT all the time.
Today I took it to the lake again and even after adjusting it all it acted the same dies in gear. I had to put the RPM at 1250 to even get it to stay at idle in gear. At higher RPM it seemed like it was following the 2nd engine but at idle it wasn't pretty.
I filmed.

I don't know if it is a problem, but I did rebuild the drive 90% of it anyways, so all the bearings seals etc. So, the forward gear, housing and bearing I think I bought new and I used the 3 old spacers, did not measure clearance, after I put it all together it was hard to turn by hand from the main axle and I also did not tighten the big round nut too much because I could not spin it anymore if I did. Forward to today or all along since and it dies in the water at idle, but it is great at 2k plus RPM. Can this be caused by the drive? If not wtf can I still do?
For Jerry I did spray starting fluid all around, by the intake carbs etc., no change.
 
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Nordin

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The prop shaft endplay and the backlash for the pinion gear and forward/reverse gear are important.
Too tight or too loose will damage the gears eventually.
Is the engine idling well in neutral (700-800 rpm) and not stay in idle in gear at 700-800 rpm?
 

gica

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The prop shaft endplay and the backlash for the pinion gear and forward/reverse gear are important.
Too tight or too loose will damage the gears eventually.
Is the engine idling well in neutral (700-800 rpm) and not stay in idle in gear at 700-800 rpm?
Yes it idles ok in neutral. In gear it shuts down unless I raise the idle speed to 1200. I am perplexed as to this issue. After going through all the repairs and I cannot get it to run right.
On water it goes ok with the other engine in tandem. But at idle it dies at 800 RPM or anything below 1100. I swapped the electronics and carbs from the other engine. I have 2 on the boat. I changed trigger and Stator and flywheel. Engine rebuilt by the book, taken to machine shop, new pistons etc. No air leaks on the sides. But now that I think about it I opened up the lower drive and changed all the bearings and front gear. This drive was full of water when I bought the boat.
After assembling it and doing torque I had to back out a bit because it was hard to turn by hand from the main shaft. I figured it was because of the all new parts. Don know for sure this is the problem but it might be.
I will take out the plugs from both engines put it in gear and try to spin the flywheel by hand to see if there is any difference between the 2. I mean sometimes it just shuts off and sounds weird. You watched the video. It sounds like crap when in gear and revving it. Before the reason I changed the trigger and stator and flywheel was because of a hesitation while running, like it would miss for a second and the engine would stutter. As it is it shakes more than the other engine.
Let me know what you think please. Thanks man for the help.
 
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