1973 johnson carb?

Motor is a 73 20 horse but carb isn't, I searched the #'s on the carb but no luck. Anybody have a clue what it is? What year and what motor it came off? Wanting to rebuild it and the primer but cant find nothing on it.

That looks like a mid 80s 20hp carb. You can tell by the severe restriction on the throat of the carb in the 1st pic. Also it has a primer, not a choke, as the front panel label states. Does it run well? You may not be able to get it to run right, as the carb is meant for a larger CC engine, but I am not sure if they changed the carb much when they switched powerheads. What do the spark plugs look like? You may be running rich or lean, even with a clean carb and working primer system.

The carb kit on this page should work:
https://www.boats.net/parts/search/BRP/JOHNSON/1988/J20CRCCA%201988/CARBURETOR/parts.html

and this is your primer
https://www.boats.net/parts/search/BRP/JOHNSON/1988/J20CRCCA%201988/MANUAL%20PRIMER%20SYSTEM/parts.html

Good luck

Thanks for the help blimp, The engines plugs look good. The engine runs good but when coming out of the hole if you open it all the way up it will choke it a little bit but otherwise runs good. I did notice after looking at the carb ipl you posted this carb is missing the low idle needle valve which could cure the idle to wot issue. Now another thing I have a question about is my carb has a screw adjustment behind mesh screen on linkage side. You cant see it in the pictures I should have gotten it but poor photography on my part. What does this screw do?

That carburetor looks incomplete. It's missing the slow idle needle, choke linkage, choke valve, etc.....etc. Is their more components that you removed and/or just showing the carburetor??

Look at this link, this is the proper carburetor that should be on your motor. (You can see there is a lot more stuff involved)

https://www.boats.net/parts/search/BRP/JOHNSON/1973/20R73A%201973/CARBURETOR/parts.html


If this is indeed a incomplete or wrong carburetor, then it may be cheaper to get a complete used carburetor. The previous owner may have tried some stuff unsuccessfully!

I know a guy on the AOMCI (Antique Outboard Motor Club, Inc) forum that may have a good used carburetor for your motor, if you decide to go that route.

I hope I'm wrong!
cajuncook1

I believe your right Cajuncook, I decided it would just to be easier to try and find a used carb thats complete then trying to redo this one. By the time I find all the missing parts and get it like it should be I think I may have more in it then a rebuilt used carb for this model. So yep I guess I am hunting know.

That is a late 80's carb. It looks complete but it doesn't exactly bolt up properly to your outboard.
Google says its a 25hp carb so the person who put it on was trying to get another 5 hp out of the motor.
You might have to bore out the port in the manifold a little larger to get that carb to work properly.
There's a lot of info on iboats about larger carb swaps. Most of the veterans on iboats claim that a carb swap doesn't work but they are full of #!%@. I don't recall a carb swap between that new of a carb and that old of a motor but it seems to work so I would just leave it but I would pop off the manifold and see if the port is the same size as the throat on the carb. You can buy a 20 hp carb of ebay pretty cheap since they are not desirable for upgrades. A 5hp larger carb won't give you much top end speed but it will give you more low end torque.

Thanks for the info WhoopBass. Also anyone know any thing about the adjustment screw on the side near the intake manifold? And what is the max rpm this outboard should spin?

Hey Buddy,

Look at this link for a 25hp Johnson late 80's carb. For starters, you have a missing slow idle needle and knob.

https://www.boats.net/parts/search/BRP/JOHNSON/1988/J25ECCM%201988/CARBURETOR/parts.html

I am going to lend a piece of advice. Now, I am not saying what whoopbass is saying is wrong! Unless your very skilled mechanically, very familiar with 2 cycle outboards, or have someone experienced enough to guide you through the process of modifying your outboard to accommodate the 25hp carb, then you don't know what the outcome will be.

My suggestion, is to find an appropriate year and make of carb with correct linkages for your choke and cam for your motor, that way you know what you got.

Whoopbass is right, you can find a carb on ebay or a savage yard.

You will need every thing in this link to make it right! (a breakdown of parts for the carburetor)

https://www.boats.net/parts/search/BRP/JOHNSON/1973/20R73A%201973/CARBURETOR/parts.html

Another reliable place to get parts is advertise on aomci.org (antique outboard motor club, inc). They have a section called webervise. It free to advertise and there are a bunch of members that have collected parts motor for different reasons and may have a complete carb for you. I have a bought a bunch of parts by webervise(advertising) on there site and have always come across honest people and reasonable priced parts.

https://www.aomci.org/cgi-bin/yabb2/YaBB.pl?board=Webvertize


I hope things work out for you either way.

cajuncook1

Thanks Cajuncook but after searching through years of johnson 20+25 horse ipl's I have decided it is a complete carb. It does have it's slow speed needle but its not in the same place as on older motors. Here is a ipl of what my carb looks like.
https://www.boats.net/parts/search/BRP/JOHNSON/1992/J25RWENB%201992/CARBURETOR/parts.html As for the port on the intake its a hair larger then the carb hole. I have decided that I will go on and repair/replace all my fuel lines and pump as needed and remove the flywheel and clean and check the points. As for the carb I think I will just try and rebuild it, The local marine store has it in stock for 17 bucks so I wont be to angry if it doesn't work. I'll keep ya posted on how it turns out

Pruitt1222 said:

Thanks Cajuncook but after searching through years of johnson 20+25 horse ipl's I have decided it is a complete carb. It does have it's slow speed needle but its not in the same place as on older motors. Here is a ipl of what my carb looks like.
https://www.boats.net/parts/search/BRP/JOHNSON/1992/J25RWENB%201992/CARBURETOR/parts.html As for the port on the intake its a hair larger then the carb hole. I have decided that I will go on and repair/replace all my fuel lines and pump as needed and remove the flywheel and clean and check the points. As for the carb I think I will just try and rebuild it, The local marine store has it in stock for 17 bucks so I wont be to angry if it doesn't work. I'll keep ya posted on how it turns out

Click to expand...

Well, it a 1990's 25hp carb on a 1973 20hp Johnson! Interesting! Yes, please let me know how things turn out. I've only dealt with engines from the 1960's and 1970's and the early 80's. I hope it works out, but did the previous owner get the motor going? Or did he sell it because it wasn't running well?

It ran very good when I got it, It still runs faily decent but I would prefer great. And for once I have the time to get it up to par so gonna take advantage of it. It has started to die after running at wot for 5 minutes or longer, Maybe fuel pump? And if it idles for long periods of time it starts missing, I replace both coils that were cracked. That helped a bunch but it still get the miss after a while. I just cant justify getting stranded on the river when I have the time and energy to get it going like it should be. I went to the marine store after my last post and picked up the rebuild kit and o-rings for the primer, While there I asked if they had any old outboard carbs and he told me he probably has 30-60 used in that style starting at 10 bucks so if it doesn't work I just have to make another trip. As for the fuel pump when I tested the motor in a barrelI had the tank on a chair about two feet or so below the motor and engine wouldn't run. I squeezed the primer bulb and could hear fuel being squirted into the bowl, I would get the bulb hard then start the engine and it would die shortly there after. Can A pump pick fuel up from that low?

Get a chair and lift the tank higher. Make sure the vent is open and not closed on the tank....done that before....lol (nobody heard that #-o )

Make sure to follow both wires going from the spark plugs are in good shape. If they have cracks in them they can short against the motor intermittently. I tried looking for a video one of the members posted and it showed spark plug wire arching in the middle against the motor and causing the motor to kill and run rough.

Good luck
cajuncook1

Sure a fuel pump can suck up fuel that low. Replace the primer bulb and make sure all of the fuel line connections are tight. Fuel pumps are pretty durable but they can go out. New points will probably help you out big time.
Good luck.

Got my fuel pump installed today, It made all the world of differance. I went out and ran it after I got it on, Had some issues first off with trying to get it to idle well. I don't know if I did something wrong when rebuilding the carb cause it was way lean at idle. I ended up turning the low idle screw out almost three full turns from all the way in. After that I ran it for about a hour and a half all over the rpm range, Solid performance out of it. So solid I am thinking about a higher pitch prop. I stoped to change fuel tanks and went to restart and broke the starter rope, Lucky for me I carry a extra rope in my little tool box. After a bit of sweating and cursin I got her fixed. Started it back up heading to the ramp and after a few miles it started to develop another miss at idle. It is a lot more extreme then the miss it had befor. Hard to explain but when it does it it will twist the motorcounter clockwise hard enugh if I dont have my hand on the tiller it will turn itself aleast 10 degrees per miss. So far I have replaced both plugs, One cracked coil, rebuilt the carb, new fuel pump and lines, clean and checked the points. When I regaped the points one was set to manual specs, the other didn't have enough adjustment but is only off .003 I have checked the wiring over for any bare spots but I may have missed something. Checked to see how hot itwas and it was cooler then my drink. Any one got any opinions on it?