1990 force 120hp outboard Carburetor help

[jerryjerry05]

NO,NO------Both carburetors operate EXACTLY the same way.----And air that goes into the top carburetor can not finds its way to the bottom 2 cylinders.

The carbs ARE connected by an "equalizer tube" on the intake.

The only difference is the fuel inlet and the throttle roller.

I believe the tab on the float should be pointing down.(bottom)

The carbs are NOT for low speed and high speed.
The jets and air screw do that job.

The air screw and jet controls the operation at low speed.
Then after the throttle's activated the high speed jets take over.

Running a motor dry???
That can cause scoring of the cylinder walls.
The 120 has screws on the bottom of the carb you can loosen to drain.
Or use Stabil to treat the gas.

 

[puffitu]

Thanks Jerry,

I stumbled upon a little Mercury supply shop in Bradenton FL, and the ole timer there said the bottom carb float was upside down as I showed him the pics. Ill follow your advise then if that doesn't produce positive results; try the other way. The carbs come out easier then I anticipated, so I am not concerned here.
However…

.wait theres more...


Im in the process of reading about adjustments to the throttle and shifter cables as it seems ive got plenty going into reverse but nothing going into forward; if that makes any sense. I probably should start another thread...Thanks guys

 

[puffitu]

Hello all

Put the carbs back on today; link-n-sync, got it going on muffs, but only after having to push throttle all the way into high. after messing with idle adjust on tower I got it to idle(in neutral position) at around 1100rpm. It sneezed a bit, but got it to stabilize somewhat after turning in the mix needle on bottom carb. I did start with 1-1.5 turns out on both carb needles then adjusted till getting it to stabilize on muffs @1100rpm. I cannot for the life in me figure out how to best sync the throttle so there is more into forward. Im doing this because when out last on the water for about three hours after redoing the head gasket and water jacket it felt like I didn't have enough throttle as it was topping out at around 4200rpm. Thanks!

 

[jerryjerry05]

There is a link and sinc post in the first 4 posts.
U-tube video by FrankA (rip)

The 4200 can be affected by load, prop, boat size, a plug not firing??

 

[blackd]

Jerryjerry and I will have to have friendly disagreement on effectiveness of running dry. After several decades of owning or running boats I have never seen scoring because of running dry. Nor have I seen the needle valve wear due to excessive movement of floats due to trailering with dry carbs. Another claim. BUT I HAVE TOO OFTEN HAD TO CLEAN CARBS DUE TO DEPOSITS FROM GAS BEING LEFT IN, and engines where confidence has been lost.

 

[racerone]

I can't believe there are still folks who say that running the carburetors dry will score the cylinders !!------Oil simply does not disappear off the cylinders when carburetor runs out of fuel.-----Just more proof that lubrication in a 2 stroke is not well understood.

 

[Redbarron%%]

If you are not getting full RPM with full throttle verify that each cylinder is firing with an induction timing light clamped around each wire.
My 90 Sport Jet ran seemingly OK except for getting full power and one cylinder was breaking down under load due to a bad coil.

 

[puffitu]

Oh shoot..ok.great info!!.I’ll have to get to that at some point. After all the work I’ve done to this thing, I’m pretty happy with the results thus far. Lowered the rpms (as Jerry said) and that is getting the engine shifting in and out of reverse a bit better.Got my bilge upand running today( without having to buy anything )
replaced the fuel sender, fuel diaphragm, put a filter after the fuel pump in, cleaned the carbs, new valve and found out that the bottom float was messed up and new valve on same carb. Not to mention the head gasket and water jacket and new thermostat, temp gage. I’m probably forgetting few things but my fiancée is calling the boat my other girlfriend so lots of going through everything. Anyways, I thought there may be a fine tune adjustment on the cables somewhere
thanks Red..

 

[puffitu]

Just a thought; does fuel octane make a big difference? I’m running premium gas-should I go to like 87-89 instead? I’ve been seeing some posts for these old Forces and it’s said that better run mid grade..?

 

[jerryjerry05]

Don't need high octane fuel.
Does nothing for the motor.

Google regular vs premium fuel.
Very educational.

 

[puffitu]

Thanks Jerryjerry05
The boat is back on the water. Had an issue with bottom carb; seemed like the float and needle wasn’t operating as it should. After taking the carbs off again, i discovered a tiny little speck of dirt stuck in the Needle valve tube causing it to stay in the closed position making fuel pee out of carb. The engine would start but die quickly. Now it seeems to have cured the problem. I’m planning to do another water test in the morning. I also feel I may have an exhaust leak from somewhere-

 

[jerryjerry05]

Exhaust leak: run with the cover on and if the motor chokes out??
Then there might be a leak?
Usually the seal under the block is where it leaks.
I had a leak on one of my motors, I used silicone over the leak and it stopped.
If it's real bad? the motor has to be pulled