1997 Force 120hp questions

captainjac15

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Hi Guys! I have a 1997 Glastron GS 160 that I picked up last year (my fifth outboard boat). It has a 1997 Force 120hp (mercury marine version). A few minor issues. The motor seems to run well at WOT and starts right up cold or hot. The last time it was taken out however, it was run for about 4 hours at idle (trolling) and it quit. Plugs were fouled. Got a tow. I cleaned the plugs back at home and she fired right up. I was in the process of winterizing the engine today, ran it for 15 minutes in the barrel to get the stabil into the bowls on the carbs. I brought the RPMs up to 2500 a couple times during this process. I don't like spraying the fogger into the carbs while the boat is running. I usually pull the plugs, spray the fogger in the cylinders and turn the engine over by hand a bunch to spread the oil around. So, when I pulled the plugs after running the engine I noticed that all four plugs had a noticeable amount of oil on them, all four were wet with oil (and no I had not used the fogger yet) I have never had this on my other outboards, the plugs are usually colored up a bit and dry. My fuel mixture was 60:1, the engine did smoke quite a bit (it was cold outside). Compression is stellar 155, 154, 155, 155. Am I missing something? Does marine stabil 360 cause this? It seems to me that oil on the plugs would definitely lead to fouled plugs again if I was to run it all day. Any suggestions? Should I decarbon in the spring and lean out my fuel:eek:il mixture for a while? suggestions on synthetic oils to use for less blue smoke? Thanks in advance guys.

Jack
 
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jerryjerry05

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Welcome.
I always thought it was 50-1​
If you run it too lean your gonna cause scoring and damage.
If you had a metering system then running at 60-1 would be automatic.
No oil tank or pump??? Then 50-1

A 2cyl will have oil residue left on the plugs.

Smoke: any 2stroker will smoke, the more you idle the more your gonna smoke.

The faster you go the less you have.
If you wanna spend the $ on synthetic you'll have less.

The Stabil stabilizes the fuel and shouldn't have anything to do with leaving residue on the plugs???

The best way to insure good fuel for next year is fill the tank and leave it full.

You have a fuel/water separator? Install one and check it a couple of times a year.
Dri-gas when the tank is low. Then fill the tank.
 

captainjac15

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Thanks for the reply! I do understand that all 2 strokes smoke because they are burning oil. I had a 40hp force for a while on a tracker and It did smoke a bit on start up and then it was fine. My concern is really with the fouled plugs on my 120hp that I have now. On that 40hp I could run down riggers and troll for a solid 8 hours and never foul a plug with a 50:1 mix. Now with this 120hp the plugs fouled up in 4 hours. After that I leaned the fuel mixture to 60:1 for one tank to see if there was a difference. Like I said I think a decarb is in order, that should help with the smoke issue. Just wondering if someone had more experience with the fouled plug situation and how to prevent it.
 

Nordin

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A two stroker burn oil and will smoke. Less smoke at higher RPM.
If you do not have an autolube system and I do not think any Force engine had it, it will have 50:1 all the time and the mix is for high RPM.s
Then it will be to rich at idle.
You troll (idle) for about 4 hours and it foule the plugs.........just normal, actualy really good.
Hit the throttle and clean it up now and then or clean the plugs....... thats life with a two stroker.

Maybe your 120Hp carbs are set a little bit rich, should be 1-1 1/4 out from seated.
BUT it is better to have it set a bit rich then to lean. To lean can melt the pistons.
 
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captainjac15

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I'll check the mixture screw on the top of each carb. There was an issue when I got the engine, it had a high idle. That was an easy fix. The "mechanic" who had worked on the motor prior to me purchasing the boat had forgot to put the intake gasket back on between the lower carb and the intake manifold, haha she was sucking air and idling high. Also I had to adjust the linkage between the top and bottom carbs so they were idling even. I never touched the mixture screw, I wonder if the guy who forgot to put the gasket back on messed with the mixture screws making it too rich so that the idle would drop down (not knowing the actual problem). Thats a good place to start.
 

Frank Acampora

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Watch the video "Tutorial." at the top of the forum (stickys) It explains synchronizing carbs and timing. Just be aware that if you change idle speed using the idle stop screw, that with Mercury controls you MUST re- adjust the control cable. You must screw in or out the black plastic slug until it just slips into the seat at idle.

As far as fouling, I always carry an extra set of plugs with me. If I see a Force owner having trouble starting I swap his and usually solve his problem.

Plugs are PROBABLY Champion L76V. If you are having that much trouble fouling, try a different brand: NGK BUHX or BUHW or Autolite (I forget the number) Do not be tempted to use bent electrode plugs--yeah, you might get away with it but then again you might melt holes in the piston crowns.

I always carry a green scrubby (Skotchbrite pad) cut into small squares. These surface gap plugs are very prone to fouling. I simply work the scrubby into the gap and clean it out. Takes all of ten minutes on the water and plugs are good forever. Seriously, I have plugs well over 10 years old and still not showing signs of wear.

Incidentally: Because of the high voltage these plugs run at, even though fouled, if you can get the engine to start and run at higher RPM, the plugs will fire through the fouling. That is why many people try to start in high idle and quickly slam the engine into gear before it stalls.
 
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jerryjerry05

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I lived on the Chesapeake Bay for a long time and trolling was most of the fishing I did.
I have twin motors and would have to switch motors after a couple of hours.

I'd think about a small 4stroke kicker for trolling?????​
 

captainjac15

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I lived on the Chesapeake Bay for a long time and trolling was most of the fishing I did.
I have twin motors and would have to switch motors after a couple of hours.

I'd think about a small 4stroke kicker for trolling?????​

I hear ya, this Glastron is more of a fish/ski boat. It is nice but the transom is shaped in a way that it would be hard to add an aux motor back there. Maybe it could be done with a lift and lower kicker mount. The boat originally came with a 90hp and the previous owner maxed it out to 120hp (max h.p. rating on the USCG plate) I do have a new 50lb thrust minn kota for it and will be adding a bow mount for that as well as an extra battery (nice and quiet). Possibly an aux charger for said motor/battery as well.
 

captainjac15

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May 5, 2015
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Watch the video "Tutorial." at the top of the forum (stickys) It explains synchronizing carbs and timing. Just be aware that if you change idle speed using the idle stop screw, that with Mercury controls you MUST re- adjust the control cable. You must screw in or out the black plastic slug until it just slips into the seat at idle.

As far as fouling, I always carry an extra set of plugs with me. If I see a Force owner having trouble starting I swap his and usually solve his problem.

Plugs are PROBABLY Champion L76V. If you are having that much trouble fouling, try a different brand: NGK BUHX or BUHW or Autolite (I forget the number) Do not be tempted to use bent electrode plugs--yeah, you might get away with it but then again you might melt holes in the piston crowns.

I always carry a green scrubby (Skotchbrite pad) cut into small squares. These surface gap plugs are very prone to fouling. I simply work the scrubby into the gap and clean it out. Takes all of ten minutes on the water and plugs are good forever. Seriously, I have plugs well over 10 years old and still not showing signs of wear.

Incidentally: Because of the high voltage these plugs run at, even though fouled, if you can get the engine to start and run at higher RPM, the plugs will fire through the fouling. That is why many people try to start in high idle and quickly slam the engine into gear before it stalls.

I did take your advice and watched the video, and also the following video that in fact was nearly the exact same motor as mine, just a 1992. I don't think timing is the issue, she runs smooth. I set the linkage on the carbs already, she idles LOW if I want it to. Carrying the extra plugs and scrubby is a good idea. Truth be told I wasn't in the boat when the plug fouling happened, it was loaned out to a close trustworthy friend. Had I been there I probably would have just used the old knuckle buster to pull the plugs and clean them (but it is risky on the open water when the plugs are on the very back of the engine, hahaha) I did buy new plugs for it as soon as I bought the boat, they are NGK (gapless) not sure of the numbers at the moment.

So what I am gathering so far is that the plug fouling issue is normal with a higher H.P. motor at idle for so long. I am thinking that the true solution is to use the 120hp for getting where I want to be, tubing/skiing/wake boarding.... and using an Aux source of power for long term slow trolling, thats just the way the world of 2 stroke works. :/
 
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