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1989 Johnson 20hp carb adjustment

Look close at the intermediate jet on thefront of the carb you may need to fab up a screwdriver to fit the hole they are in pretty tight. I have the sneaking suspition it has been reamed out. What elevation are you running the engine?
 
kimcrwbr1 said:
Look close at the intermediate jet on thefront of the carb you may need to fab up a screwdriver to fit the hole they are in pretty tight. I have the sneaking suspition it has been reamed out. What elevation are you running the engine?
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No elevation..... I'm in Florida where a 2 feet elevation over a one mile stretch is considered a "slope".... lol
 
racerone said:
Be careful when you decide to " re-engineer " this stuff or make changes !!
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And the carb seems to be doing a good job as is (aside from the coughing and stalling when choke is pulled off) so I wonder if I shouldn't leave those openings the way they are after the cleaning.....???
 
I just found a 25hp carb with the screens there what size is the high speed jet in the float bowl? Possibly someone wanted to gain some ponies. They are probably for the bowl vent?
 
kimcrwbr1 said:
I just found a 25hp carb with the screens there what size is the high speed jet in the float bowl? Possibly someone wanted to gain some ponies. They are probably for the bowl vent?
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Got pulled away yesterday, didn't get a chance to take it apart yet, will let you know later today.
But if you found one with screens it might have been made this way from the factory then?
I would be surprised if this motor had been hacked by anyone. It looks pretty stock and well maintained. Lubed, greased and all...
 
racerone said:
See post # 31
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Yep, saw it and I agree.

If there's one component I'm not about to mess with on a 2 stroke motor, it's definitely the carb..... the slightest mod of these animals can (and will) translate in the motor never working right again!
I've always been dumbfounded by the engineering work behind the making of a carburetor, and not about to interfere!! lol

And as I said earlier, I don't think those screens are the work of an amateur. The way they are inserted in the carb body kinda tells me it's a factory thing, not aftermarket.
I'm just surprised that I can't find documentation on those online..... maybe they will be mentioned on the service manual I ordered, when the damn thing finally shows up in the mail!

kimcrwbr1: The one you found with those screens, do you know the year model of the motor it was on?
 
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Best to relax----read the manual 2 X before turning a wrench.------Outboard motors are wonderful machines and they are often ruined by folks who were guessing at how they work.
 
Also, has any of youse guys seen a metal plate (stamped with numbers) as you can see on the bottom pic of post# 28 held on the carb by one of the bowl screws before?
 
It looks like they used that design in the late 80s early 90s and went to the flat top. That engine had the same displacement in 20-25-28 and 30hp. I am not a big fan on the carbs with both a slow needle and a intermediate air jet. Mid to late 80s had the slow needle on the front of the and easier to dial in IMO.
 
kimcrwbr1 said:
It looks like they used that design in the late 80s early 90s and went to the flat top. That engine had the same displacement in 20-25-28 and 30hp. I am not a big fan on the carbs with both a slow needle and a intermediate air jet. Mid to late 80s had the slow needle on the front of the and easier to dial in IMO.
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Thanks, and yes that's what I figured also. Doing some research on Ebay I found a listing (linked below) with the exact same carb taken off a Suzuki oil injected 25 hp! (Listed as fitting 89 Johnson).

https://www.ebay.com/itm/Suzuki-DT2...ash=item2f0578a941:g:lN8AAOSw-29ZQWQ0&vxp=mtr

Now I hope the carb repair kit I ordered will have the correct parts for my carb.... what a cluster!@#$.
 
You should be fine just replace the parts in the kit you take off of that carb. Float needle and seat, gaskets, soft plug. I always pull the jets and blast everything good with hogh pressure water to scour the circuits. Make sure the float is level and square and never put fonger pressure on the float pull it and then check it with the weight of the float only. The gasket in the center pf the float bowl is the most common item forgot FYI.
 
kimcrwbr1 said:
You should be fine just replace the parts in the kit you take off of that carb. Float needle and seat, gaskets, soft plug. I always pull the jets and blast everything good with hogh pressure water to scour the circuits. Make sure the float is level and square and never put fonger pressure on the float pull it and then check it with the weight of the float only. The gasket in the center pf the float bowl is the most common item forgot FYI.
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Thanks for the info!
When you mention high pressure water, what kind of device do you use for that? (I have an air compressor but nothing to send high pressure water on parts)
 
So I took the carb apart, and found out that those screened ports were conduits connected to the bowl, with one side open one side plugged:




At first I thought someone had messed and forgot the plug, but the (unplugged) opening doesn't have the machined groove that would allow seating a plug in there, so I guess that is how it's supposed to be...
 
Take a good look and see if there is a passage way that had to be drilled.---Then access is plugged.----Your investigation is leading you nowhere !
 
racerone said:
Take a good look and see if there is a passage way that had to be drilled.---Then access is plugged.----Your investigation is leading you nowhere !
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You lost me here.... all I'm saying is the carb body was designed, and molded with TWO air vents leading to the bowl, but one is supposed to be plugged.
My question is why make a carb with two air vents if only one is needed?
A possible explanation would be that in some applications (with a different motor) both openings are unplugged to allow a greater air mass in maybe?...

Nothing I'm gonna lose sleep on, mind you, just sharing my observation.
 
The one that is plugged is actually air for the high speed emultion tube the brass tube center of the float bowl going up to the nozzle. It helps the fuel atomize before entering the venturi. The little holes on the side of the tube basically causes the fuel mix to bubble as it is sucked from the float bowl.
 
kimcrwbr1 said:
The one that is plugged is actually air for the high speed emultion tube the brass tube center of the float bowl going up to the nozzle. It helps the fuel atomize before entering the venturi. The little holes on the side of the tube basically causes the fuel mix to bubble as it is sucked from the float bowl.
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Ahhhhhh now I see. Thanks for the breakdown!...
 
Jupiter Dinghy said:
I'm saying is the carb body was designed, and molded with TWO air vents leading to the bowl, but one is supposed to be plugged.
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Look closely.... The opening on the left (carburetor pic) is a air vent... if air can't get out, fuel can't get in.

The opening on the right (core plug sealing it) is not a vent. Notice the bulging casting leading from that plugged opening to the fuel passageway of the brass high speed nozzle. That core plug is sealing the drilled hole that serves for a fuel passageway.
 
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