Force 120 timing / Fuel Mixture

[gydatree]

I just put a 96ish Force 120 on my pontoon, and the guy i got it from insisted i do the timing. I didnt realize that til after running the boat a bit, didnt notice anything wrong as it ran great. So I went back and setup for the timing, and it was at about a little over 10ish I think. After asjusting I got it up to the recommended 28 at WOT and it ran extremely high, and knocked some when you have it any throttle. I adjusted it back down to where it idled just right, which was a bit higher than it had been previously set (it did have low idle b4 and stalled once or twice), and it ran great all day.

Do I need to be worried about anything else? Is there something else I can adjust to make it idle right at 28? Am I risking damage by running it under 28? I never did think to check it at neutral, looking back I should have. But I do want to make sure I dont waste this motor, as it replaced another 2 stroke with oil injection problem that burned up.

Also, as for the mixture. I have been doing 1 quart for every 12.3 gallons and 1 pint for 6.15 gallons, putting the oil in 1st to mix, all non ethanol gas. It does seem 2 smoke a bit at times, but seems 2 run strong, no problems whatsoever.

I grounded all spark plug wires, dont think it had the safety switch as I didnt see one and it cranks with the throttle at WOT. I connected the timing light to number 1 and cranked it. I adjusted the screw under the trigger with the locking nut until i got it to 28, and it made it run way to high.

Is there a different way to get it to WOT or something? Like by maybe disconnecting the throttle cable and moving the throttle levers to WOT manually? Does it make a difference if I did it in the water?

Where it is set now sounds right, solid at low idles and WOT.

 

[Texasmark]

I just put a 96ish Force 120 on my pontoon, and the guy i got it from insisted i do the timing. I didnt realize that til after running the boat a bit, didnt notice anything wrong as it ran great. So I went back and setup for the timing, and it was at about a little over 10ish I think. After asjusting I got it up to the recommended 28 at WOT and it ran extremely high, and knocked some when you have it any throttle. I adjusted it back down to where it idled just right, which was a bit higher than it had been previously set (it did have low idle b4 and stalled once or twice), and it ran great all day.
---------------------------------
Reply:
I don't have a Force but 28 is pretty close to where my Merc runs....22. Spark advance affects idle speed, faster you set it, faster the idle.....that's what timing advance is all about....leading the engine to a higher rpm.

On my 90 timing sets the idle speed, not carb (throttle tweaks) like in days of old. At idle it is actually "after" ATDC 4 degrees for a book speed of 675 +/50 in the water in F gear, boat moving. This translates to roughly 800 in the driveway on muffs, in N.

Knocking is pre-ignition and caused by the fuel mix exploding before it's time.....aka too low on your octane (89 actually was recommended for my Merc but I ran 87 with no problems), or too fast on your timing....the 28 BTDC may be too high.
-----------------------------------
Do I need to be worried about anything else? Is there something else I can adjust to make it idle right at 28? Am I risking damage by running it under 28? I never did think to check it at neutral, looking back I should have. But I do want to make sure I dont waste this motor, as it replaced another 2 stroke with oil injection problem that burned up.
----------------
Reply:
As I said earlier, timing advances lead the combustion process which helps the engine to gain rpms. So, if you lower your timing, you just may be putting it where it needs to be. You also will find the engine runs smoother with reduced timing. However you may notice a bit of sluggishness from what you currently have. If you think you need that advancement, run high octane fuel which helps to control pre-ignition at a given combustion pressure.

"Oil injection failure" is one reason that on my 10 year old Merc I disconnected mine and just ran pre mix [One pint of Pennzoil premium semi-synthetic TC-W3 (2 cycle engine, water usage, 3rd iteration) which you can get in the sporting goods section of WW for a good price, added to 6 gallons of unleaded gas....referred to as the 50:1 ratio). While you are there (at WW) go to the auto section and get a couple of cans of Sea Foam (fuel additive). Read the directions. You won't be wasting your money. BTDT
--------------------------------------

Also, as for the mixture. I have been doing 1 quart for every 12.3 gallons and 1 pint for 6.15 gallons, putting the oil in 1st to mix, all non ethanol gas. It does seem 2 smoke a bit at times, but seems 2 run strong, no problems whatsoever.
-------------------------
Reply:
Obviously answered this above. You are good to go on your mix. The Pennzoil prem. semi oil and the Sea Foam will in time reduce your smoking to practically nothing.....will take a little time for it to clean out the crud in your engine but when it gets cleaned out you will hardly know you are running a 2 stroke. BTDT too.
-----------------------------------
I grounded all spark plug wires, dont think it had the safety switch as I didnt see one and it cranks with the throttle at WOT. I connected the timing light to number 1 and cranked it. I adjusted the screw under the trigger with the locking nut until i got it to 28, and it made it run way to high.
-----------------------
Reply:
Timing in my manual said fresh battery, plugs out, light on #1 as you have done. What I prefer to do is to install the caps on the plugs and wrap a grounded piece of wire around the threads. This allows the high voltage circuit to operate at near normal conditions rather than being allowed to run up to the 40kV open circuit voltage, or have the energy dissipated internally with a short circuit for a load.
-------------------------
Is there a different way to get it to WOT or something? Like by maybe disconnecting the throttle cable and moving the throttle levers to WOT manually? Does it make a difference if I did it in the water?
-----------------------------------------
Reply:
Nope. Use your remote control all the way forward. Look at your butterflies in your carbs. If they are perfectly aligned with the carb venturi they you are setup right. If not, back at the engine, where the cables mount, run your brass barrel up or down the cable till you can manually adjust the engine for what I said and the cable "fits" the engine throttle positioning.
-------------------------------------
Where it is set now sounds right, solid at low idles and WOT.
-------------------------
Reply:
"Don't Fix it if it Ain't Broke" Grin
---------------------------

What else needs "fixin"?

You would do yourself a favor by checking the lower unit gear lube. You can do it on the boat, and the best time is after the boat has been sitting for a day or so.
Get a small (1 pt???) container and a large flat blade screwdriver. Turn the steering wheel fully CCW. This should turn the engine, with it in the full up position, so that the drain screw is up where you can get to it. Carefully loosen the drain screw so that you can get your fingers on it...don't let the oil out yet.

I know it's awkward but it's best to now turn the steering wheel fully CW when you get ready to take the sample....reason is that if there is any water in there it will be on the bottom, at the screw port, so you can drain it out first....oil floats. Remove the screw and let a small amount of oil into the container.

If water comes out first, so be it...stop there. Reinsert the screw, roll the engine back over and have a look at the oil. If no water, no bubbles in the oil, color is blue black, you are good to go. Lock the screw back down. If anything else you need to drain and refill; awkward on the boat but it can be done.

WW has the quart bottle of Mercury/Quicksilver Premium LU oil, fill tube and engine attachment, all in one package, in the sporting goods section. 1 qt. will fill it easily. If you never did that before come back and I'll tell you how.

 

[gydatree]

Are the plugs supposed to be removed from the motor? I had them unplugged with the wires grounded, but the plugs were still in the powerhead.

The gas Ive been running is non ethanol, I think 90 Octane. I did a Seafoam decarb on a 99 tracker 60 bigfoot and it made it run beautifully. Should I just run a little bit at a time whenever i put gas in, or do a separate tank with the 16 oz seafoam mixed with a bit of gas and run at idle in 15 min incriments with 15 breaks until either the mix or the smoke is gone? I think that heavy mix may have stirred some parts of a fuel line and stopped a carb once or twice, but did work its way through. I wasnt sure if the decarb had been done on the force or not, so i was hesitant to do it.

Also, I used the same throttle cables from the merc 90, made small adjustments to connect them properly. I later readjusted one to make the lever for WOT go all the way forward when the throttle is all the way forward. That seemed to make it sit in neutral better as well.

The impression I got in getting this motor is that it had been maintained pretty well, which, it has ran pretty flawlessly for us back and forth across a big lake all weekend. I did the gear lube on my merc 90, and could do it no problem on this one. It does seem to have a slight vibration wheen accelerating at low speed, but once it gets going its smooth, prop isnt dinged or anything. But yes, I will give it a check.

Also, b4 I did anything with this motor, I replaced the stator, trigger and switch box, and used the existing wiring harness from the merc 90. The trim on the throttle worked fine to begin with, but after being out for a while it only worked on the motor. Is there a fuse or something I should check for that? Wires are still connected inside the motor.

Thanks for the advice! I just want to make sure Im not risking blowing a piston or something by not having the timing exact, even though its been running great. I never did check the timing again after we left the dock with it, as I just adjusted it til it sounded and right and off we went.

 

[Texasmark]

Are the plugs supposed to be removed from the motor? I had them unplugged with the wires grounded, but the plugs were still in the powerhead.
-------------------
No. Need engine to spin up fast off the starter and plugs are a hindrance....serv. manual. req..
------------------
The gas Ive been running is non ethanol, I think 90 Octane. I did a Seafoam decarb on a 99 tracker 60 bigfoot and it made it run beautifully. Should I just run a little bit at a time whenever i put gas in, or do a separate tank with the 16 oz seafoam mixed with a bit of gas and run at idle in 15 min incriments with 15 breaks until either the mix or the smoke is gone? I think that heavy mix may have stirred some parts of a fuel line and stopped a carb once or twice, but did work its way through. I wasnt sure if the decarb had been done on the force or not, so i was hesitant to do it.
--------------
Well sir you don't need convincing. Do it. When you finish, if worried, pull the drain plugs on your carbs and with your primer bulb pump some fresh fuel through your carbs....filll drain fill drain a couple of times. I ran it in every tank adding.about 2 oz to a gallon of the regular ratio pre-mix
-------------------
Also, I used the same throttle cables from the merc 90, made small adjustments to connect them properly. I later readjusted one to make the lever for WOT go all the way forward when the throttle is all the way forward. That seemed to make it sit in neutral better as well.
-------------------
That's the way Merc designed it for that very reason.
-----------------------
The impression I got in getting this motor is that it had been maintained pretty well, which, it has ran pretty flawlessly for us back and forth across a big lake all weekend. I did the gear lube on my merc 90, and could do it no problem on this one. It does seem to have a slight vibration wheen accelerating at low speed, but once it gets going its smooth, prop isnt dinged or anything. But yes, I will give it a check.
-----------------
You can get on a concrete pad of some sort with your boat on the trailer. Adjust the pad so that it is some visually measurable distance from the ground to the end of your prop shaft....the detent in the center is a good spot as that's where it is chucked in the lathe to machine. Rotate the prop through 360 and check for any out of round. A few thousandts is ok. Next pic a point on the tip of one blade as you rotate the prop and do the same thing checking the max. deflection of each blade tip. If pretty uniform fine. You can consider that if those two measurements are ok, your problem is fuel/ign. and I'd bet it's fuel flow and will clear up once you do your decarb and all and get the carbon and all flushed out of the engine.
--------------------------------
Also, b4 I did anything with this motor, I replaced the stator, trigger and switch box, and used the existing wiring harness from the merc 90. The trim on the throttle worked fine to begin with, but after being out for a while it only worked on the motor. Is there a fuse or something I should check for that? Wires are still connected inside the motor.
----------------
Somewhere under the cowling (inside the motor) is a Y where the motor and remote wires diverge. You have proven that things work up to that point. First guess is the switch on the RC. An ohm check would do. It's a SPDT -MC (single throw, double throw, momentary contact) switch. You should get a short from the center to the outer terminal of whichever direction you pushed the switch. If not you broke a wire somewhere but don't bet on that....the switch is your smoking gun.
--------------------
Thanks for the advice! I just want to make sure Im not risking blowing a piston or something by not having the timing exact, even though its been running great. I never did check the timing again after we left the dock with it, as I just adjusted it til it sounded and right and off we went.
----------------
Things go faster when you are familiar with that with which you ask question.
Good luck.

 

[gydatree]

Ok, great, thanks again for all of the advice. So, the last question for now is about the timing.

On the throttle tower with the timing screw at the top that i adjusted to get it to 28, I looked for what might look to be the idle screw, and I found what it might be, but couldnt turn it with a screwdriver. Maybe if I hit it with some wd 40 it might, but I didnt want to risk stripping it or it not being the idle screw.

My question is, should I go back and set it back to 28 and then try to turn that screw to get the rpms way down at idle? The reason that doesnt really jump out as the answer to me is that when I got it to 28, the top timing screw was inside the plastic piece, screwed way in from where it was, just seemed like it may not be right.

The only other thing I can think of that may affect it is the battery. It starts strong everytime, and has always shown a strong 12 volts, but I havent put a meter to it in a while to verify.

 

[Texasmark]

First off I need to make a correction to your earlier question about plug removal. When I said no I meant that no they aren't to be installed. You need the plug holes open so that there will be no compression and the engine can spin up faster.
----------------------------------------
Ok, great, thanks again for all of the advice. So, the last question for now is about the timing.

On the throttle tower with the timing screw at the top that i adjusted to get it to 28, I looked for what might look to be the idle screw, and I found what it might be, but couldnt turn it with a screwdriver. Maybe if I hit it with some wd 40 it might, but I didnt want to risk stripping it or it not being the idle screw.
---------------------
Move the throttle linkage back and forth in the idle viscinity while looking in the engine parts moving. One of the arms moving will have a knurled screw with a spring support, may be black alum, or white nylon. That screw keeps you from moving the linkage any farther in the idle direction. If it controls spark timing you will see it connect up under the flywheel while the linkage to the carbs doesn't move. That's the one you want.
----------------------------
My question is, should I go back and set it back to 28 and then try to turn that screw to get the rpms way down at idle? The reason that doesnt really jump out as the answer to me is that when I got it to 28, the top timing screw was inside the plastic piece, screwed way in from where it was, just seemed like it may not be right.
---------------
A couple of pictures taken from 18", well focused, would help.

The only other thing I can think of that may affect it is the battery. It starts strong everytime, and has always shown a strong 12 volts, but I havent put a meter to it in a while to verify.
--------------
You want a strong battery so that a low battery won't impede your timing work. How fast you spin the engine has no effect on the ignition timing but it determines how many times the timing light illuminates your marks (how bright)and that can make a difference, especially on the drive way in the sun.

 

[gydatree]

Does the plugs being in or out affect the timing number or just how many times it spins and how many times you can see the numbers?

 

[Texasmark]

Does the plugs being in or out affect the timing number or just how many times it spins and how many times you can see the numbers?

How many times you see the numbers. Timing is angular displacement, not angular velocity.