mixture fuel air force 125 89.

[shakazulu]

I read the sticky for mixture adjusting. If I turn needles clockwise I increase fuel and decrease air. If I turn needles counterclockwise I increase air and decrease fuel. Am I correct? What are the simpthoms of bad mixture? My motor never starts at first, I need to crank it 2 or 3 times untill it starts, first with choke, later without. And spends lot of fuel, or maybe it is default. I would like to set it correctly. Thank you for help

 

[jerryjerry05]

Re: mixture force 125 89.

Re: mixture force 125 89.

Turn it out 1 and 1/8th turn out and leave it till you can put it in the water.
The idle in gear,motor warm and in the water is 750-800rpm.Then reset the air screw. Running motor:In till till it just starts to miss/cough/buck or stall then out 1/2 turn.
If your using too much gas it could be:fuel pump diaphram,wrong prop,water soaked foam,timing off.
What are the RPM's at WOT?What prop are you running?

 

[shakazulu]

Re: mixture force 125 89.

Re: mixture force 125 89.

Thanks for reply. I don't have tachometer originaly but I bough one for my motor but I can not figure out why it does not work .
It worked for half an hour and then stopped. I am not sure did I somehow burn tachometer. Is there a way to check faria 20 pole tachometer does it work ?
Boat goes 30MPH it is 1902 bayliner capri . I tried to find info on the prop but there is no sign on it, I will have to measure it to find out size.
Fuel diaphragm seems so look good and there is no soaked foam. Timing is correct maybe 95%. I think that motor spends 2 liters on 1 mile going 15-20 MPH.

 

[Jiggz]

Re: mixture force 125 89.

Re: mixture force 125 89.

The prop that came with my 1989 125 HP Force is 13.25" X 17. As for the idle mixture adjustment, actually turning clockwise reduces the fuel or makes the mixture leaner while going counter clockwise makes the mixture richer (or increased fuel to idle). After following the sticky for adjusting idle setting, what I do is ran the boat for a couple of days and then take note of the exhaust (heavy or light) and then pull each plug to check conditions. If the plugs are highly carbonated with heavy wetting the mixture is still too rich. Then I'll adjust the idle screw clockwise 1/8 of a turn (on both carbs assuming all plugs indication is the same. If only the top (2) plugs are showing heavy carbons and wetting, then adjust only the top carb and vice versa. Keep doing this until the plugs show little to no carbonation with very little wetting. Plugs should never look clean and dry, which means the mixture is too lean which can cause cylinder scoring or piston failure. Instead plugs should look a little to dark tan (not black) with little wetting. When proper setting is achieve, mark with a scribe or seal with loctite red sealer.

 

[jerryjerry05]

Re: mixture force 125 89.

Re: mixture force 125 89.

The way to screw up the pistons is messing with the air screws.Set it like I said.You can even leave it at that setting.The factory in 1989 said to open the air screw out 1 turn and leave it.
You can try to adjust the color of the plugs and burn your pistons at the same time.
Remember the gas has oil in it.It's supposed to look black and oily.Tan is too lean and will burn the pistons.
A 4 stroke the color can matter not a 2 stroke.
They sell an item called a Tiny Tach. Hook it to the top piston and it works great.
Once the air screws are set don't screw with them.Or you'll be asking how to rebuild.

 

[Sprky]

Re: mixture force 125 89.

Re: mixture force 125 89.

Low speed air mixture is just that. You cannot burn a piston by changing that adjustment. The best way I found to adjust the mixture is to pull bottom two plugs out start the motor. Start at one turn out like Jerry indicated and make your adjustment on the top carb until you get best idle. Repeat process for the other two cylinders. Put the boat in the water and adjust idle screw so the motor will go in gear without dying.

Chris

 

[Frank Acampora]

Re: mixture force 125 89.

Re: mixture force 125 89.

Uh, Chris---You happen to be wrong. I have gone over this innumerable times. Since the low speed circuit is always at manifold vacuum, it always delivers fuel AND the high speed jet is sized to compensate for this. Argue with me if you want, but that will not make you correct.

Setting low speed needles too lean is a fast way to spend money on a rebuild. Listen to Jerry! He knows his sh**

 

[Sprky]

Re: mixture force 125 89.

Re: mixture force 125 89.

Setting low speed needles too lean is a fast way to spend money on a rebuild.

If that were the case, everytime a customer came in my shop with a force that wouldn't idle well but would run down the lake fine, would need a rebuild.

I have 24yrs. working on this stuff.

Chris

 

[Frank Acampora]

Re: mixture force 125 89.

Re: mixture force 125 89.

And 24 years of doing it wrong. Don't try to pull rank on me because I have been wrenching Forces and Chryslers since 1967.

 

[Sprky]

Re: mixture force 125 89.

Re: mixture force 125 89.

Then why would you advise someone to hone a cylinder with a motor assembled, knowing full well that there is no way to get all the grit out, not to mention a spring loaded hone will make a mess of a cylinder, cause the guy running it hasn't got a clue. And then there is also the possibility of the rod cap being put on upside down or at minimum, misaligned and destroying the crank.

I have seen "factory trained" people that couldn't wrench their way out of a wet paper bag. I have also seen some pretty sharp guys that have figured it out on their own.

Chris

 

[Frank Acampora]

Re: mixture force 125 89.

Re: mixture force 125 89.

I advise people of all their options and let them decide what they want to do. Everything I advise is something I have already done with good results. AND if you look at previous posts of mine you will see that I also explain the hazards of a procedure.

Don't you think this guy would come back for further instructions before starting?

I told you, you can argue if you want, but it still won't make you right. Back to the original: setting low speed needles too lean will result in melted pistons.--Case closed.

 

[Sprky]

Re: mixture force 125 89.

Re: mixture force 125 89.

Don't you think this guy would come back for further instructions before starting?

Probably not!

The Idle/progression holes are down stream from the venturi. When the butterfly is past half throttle there is no pull on them. The pressue drop is at the main nozzel.

Think about how I adjust the low speed mixture. Do you really believe that the motor will run on two cylinders with the screws set on the lean side?

Your familiar with voulmetric efficiency, right?

Give it a whirl.





Chris

 

[Jiggz]

Re: mixture force 125 89.

Re: mixture force 125 89.

Frank and Chris, you're both obviously the expert on this one. However, I based my post on p.133 of Clymer's 4th edition which discusses spark plug analysis. I've personally done the same and followed the manual to the letter. Yes, too lean can cause major problem. And with too rich of a mixture it could keep fouling your plugs. And its also accurate that the idle mixture only affects lubrication when idling. When the engine revs up and start taking on fuel/oil mixture from the main jets, proper lubrication is basically automatic since there is no adjustment for the main jets. So even if the idle mixture is set at the lower end of the fuel/oil mixture, it'll take a long time before catastrophic damages can occur. And only if the setting is too lean. However, if there is any sign of wetting even at the slightest on the plugs after a long idling, it sure guarantees that there is proper lubrication at idling. As mentioned, there should be a little wetting on the plugs.

Oh another thing, why they keep calling the idle mixture screw an "air screw" is beyond me. The only thing that adjust air is the "butterfly" or throttle valve which is located at the throat of the carb. The idle mixture screw adjusts the fuel going to the idle jets, not air.

 

[Sprky]

Re: mixture force 125 89.

Re: mixture force 125 89.

Look at it this way.........................If the mixture screws were that critical to topend operation, the engineers would have capped them or used fixed jets, otherwise these things would be buring up left and right....... By nature, if we see something that can be adjusted the first thing we do is adjust it.

If you can't get the idle you want, you might try cleaning the bleed system. Quite often it will get filled with crap and all the adjusting in the world won't make a difference.

Very few people can read plugs... The easy way is time to speed. A two stroke always performs best on the rich side of the curve. (Volumetric efficiency) A stop watch will always tell you exactly what the motor wants.

Chris

 

[labawg]

Re: mixture force 125 89.

Re: mixture force 125 89.

While I?m still a newbie to outboards I?m not totally to two cycle engines. A few years back I had the opportunity to speak to a Tillotson engineer on this subject and he stated only when the engine approaches WOT and the Butterfly is nearly horizontal (wide open) do the idle circuits no longer come in to play. This discussion was about scoring cylinder walls at cruising speed (two third WOT)

 

[Jiggz]

Re: mixture force 125 89.

Re: mixture force 125 89.

Well, you try proving the engineer's view if it's accurate or not but shutting the idle screw all the way in (on all carbs), which basically shuts it. Do not force the screw tight or it'll get damaged. Then try starting the engine while holding the carb's tie bar 1/3 open or even 1/2 open. If it starts the engineer's view is inaccurate. But if the engine didn't start until WOT or the throttle at horizontal then the engineer's view is accurate. My bet is on the former rather than the latter.

 

[labawg]

Re: mixture fuel air force 125 89.

So you are telling me if I shut off the idle mixture srcews I should be able to run my motor just fine with no ill effects provided I don't idle the motor?

 

[Sprky]

Re: mixture force 125 89.

Re: mixture force 125 89.

While I?m still a newbie to outboards I?m not totally to two cycle engines. A few years back I had the opportunity to speak to a Tillotson engineer on this subject and he stated only when the engine approaches WOT and the Butterfly is nearly horizontal (wide open) do the idle circuits no longer come in to play. This discussion was about scoring cylinder walls at cruising speed (two third WOT)

Things that make you go HMMMMMMM..............

Chris

 

[Jiggz]

Re: mixture fuel air force 125 89.

With the idle screw needle all the way shut there won't be any fuel for idling which means the engine will not even start or run unless you have the throttle valve at least 1/3 to 1/2 open or maybe even more. And yet you're posting what the "engineer" told you like an evangelist spreading the "word"! Are you sure this guy is actually an engineer? And not a "Gin-gineer" whose favorite drink is Gin? Anyways, try what I told you and let us know what happens. Believe or not, with the idle screw shut that engine of yours will never run unless you manually opened those throttle valves using the tie bar! As for what that Tillotson engineer told you, well, I'd rather have you find out first hand instead of me making a call!

 

[labawg]

Jiggz, I?m a little confused with your post, in my post I stated ?do the idle circuits no longer come in to play? meaning fuel being delivered from the idle system is diminished as the motor approaches WOT. At WOT all or mostly all fuel is being delivered by the main jets. There is a period of crossover when fuel is being delivered by both the idle system and main jets. BTW your right EC is not degreed engineer (at least that I know of) but I truly doubt he?s a ?Gin-gineer?.