1959 Johnson 18hp Carb cleaning and adjustments (manual)

[roger56]

Looking for instructions on cleaning and adjusting carb.

[Joe Reeves]

Make notes, take pictures... your memory won't do it! The cleaning is up to you.

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

[roger56]

this motor looks like it has two rings together one red one white that are the adjustment needles? Which one is low and High?

[Joe Reeves]

You can temporarily disconnect any linkages in order to adjust initially.

Top needle valve is slow speed.

[roger56]

I am not sure what you mean by top needle valve? It looks to me that Both adjustments are in the same location one ring is white, one is red inside of the white one. I hope I am in the right location here? This area is accessible from the outside of the front of the motor with the coweling still on.

[roger56]

I am not sure what you mean by top needle valve? It looks to me that Both adjustments are in the same location one ring is white, one is red inside of the white one. I hope I am in the right location here? This area is accessible from the outside of the front of the motor with the coweling still on.

I will be working on this motor tomm thanks for all the help!!!!!!!

[HighTrim]

Joe told you what to do, you have to disconnect the linkages in order to seat the needles. You cannot do it with the faceplate on.

In regards to your question, the larger white dial is the high speed, and the interior red dial is for the low. They are usually well worn though from neglect from '59, and are hard to adjust the needles with. I remove them, fine tune, then just put them back on for show. Not a big fan of OMCS design that year.

There is also a sticky in the TOp Secret Files which will help with the rebuild by Tashasdaddy.

[Joe Reeves]

I am not sure what you mean by top needle valve? It looks to me that Both adjustments are in the same location one ring is white, one is red inside of the white one. I hope I am in the right location here? This area is accessible from the outside of the front of the motor with the coweling still on.

You must dismantle the linkages to a certain point. As it stands on that model, you cannot move either needle valve more than a 1/8 turn or so. Those exterior knobs are just for final day to day minor adjustments if needed.

[roger56]

Thanks I feel like i have a handle on this now will let you know more tomm. I was reading about DCARBing a engine would this help in this case?

[HighTrim]

Not regarding your carb, a good idea none the less though.

[roger56]

Well went to work on 59 Johnson today took all the advice and info I could find. Heres what Happen Put in all new gas per specs. Cleaned The High speed and Low speed needles Not dirty at all. Reset both needles Per Specs. Started it up low speed Idle seemed to be fine. But could not get engine to Incresed rpm speed at dock. Its like the throtle gets stiff when you try to incrase speed. So I thought may it needs to be in Gear to adjust High speed needle. Out on the lake I went Still no Increase in speed. Then Motor dies. and to compound things the motor has electric start. it quits working. Floating away Then the key finally starts motor only runs for few minutes and very slow speed and dies again. Paddle my way back to the dock Park it. Key will not turn motor at all now. Im confused What did I do Now. Thought it was the Key switch bought a new one still dead? So I parked it and will attempt to figure this out tommorrow any help would make my 4th of july to get this boat on the lake

[roger56]

I also did find the manual for this motor. It has a lot of Pictures and Info But Not much on the starter that was probably put on after this motor was installed on the poontoon.

[HighTrim]

You need to clean the carb. Simply removing the needles is not enough.

You need to start with the basics. What is the compression? Will the spark jump a 3/8" gap on both cylinders on an inline tester with a bright blue ZAP!!?

May have battery issues, may have connection and wire issues. Start by ensuring the battery is fully charged and load tested. Then clean all connections with a file and retighten. If any of the wiring has nicks/cuts/abrasions, OR it will crunch when flexed, it will need to be replaced. Voltage drop testing is a good method of locating faulty sections of wiring.

There is actually a good thread in the FAQ entitled "Outboard Wont Start" by JB, follow those steps and let us know what you find.

[roger56]

Thanks I will be working on that tommorrow I have a place to start. will let you Know what happens next.

[kfa4303]

HI roger this link can help you through a basic carb rebuild. It's for a slightly different model, but the basic steps are the same. You can get new carb kit right here at iboats for about $25. Holler if you get stuck.

http://www.outboard-boat-motor-repai...%20Tune-UP.htm

http://www.leeroysramblings.com/john...D_15_18hp.html

http://forums.iboats.com/engine-frequently-asked-questions-faq/carb-needle-adjustments-asorted-carb-variations-joe-reeves-167352.html

[roger56]

Did compression check today 92-93 PSI on both cylinders. Good spark on both Plugs. I also looked at the electrical issue There must be at least 3 or 4 feet of extra wire coiled up inside of bottom cowling area. Moved some of the wires around and found some areas that were melted through and grounding against the block. It looks like there is way too much wire wraped up in there. Whats normal This group of wires go to the starter switch. 5 wires total all going into the key switch. I will probably just Change the entire cable It looks very new but starting key switch does not work all the time One time yes Next time no. When pulling plugs from previous days Bottom cylinder looked good Top cylinder Looked like a desert almost white and very dry Like no fuel is reaching cylinder? I got a feeling I know where this is going to go Carb!!!! Today again when stating Could not get and High speed Rpm from Motor and When trying to get the RPMs the throttle seems to be Hard to move when trying to increase When at low Idle it works fine. Any Thoughts?

[KillerKilgore]

I also did find the manual for this motor. It has a lot of Pictures and Info But Not much on the starter that was probably put on after this motor was installed on the poontoon.

... must be at least 3 or 4 feet of extra wire coiled up inside of bottom cowling area. ...
... some areas that were melted through and grounding against the block. .... key switch does not work all the time ...
... Could not get and High speed Rpm from Motor and When trying to get the RPMs the throttle seems to be Hard to move when trying to increase When at low Idle it works fine. Any Thoughts?

I'm no expert here but sounds like you have a lot of little troubles. lets work on them one at a time.

1. if the engine is installed on a pontoon how do you control the throttle. By cable? If so it may be that the cable is binding and not allowing you to get full throttle. could be crud built up. I know on my 10 hp it only has a twist grip and that gets built up with crud and cannot get full throttle. my to will not let you get full throttle unless you put it in gear. a pic would help.

2. extra wire is not a good thing. melted wire is not a good thing.

3 key switch not working may be the melted wires or could be a safety switch. not letting it start in gear or full throttle

below is page containing a electrical diagram for a 18 hp johnson. post some pics and we can see where to go from there. maybe start one thread for each problem and work on one problem at a time. or keep this one going and just work on 1 thing at a time. not 5 problems at once.it helps to KIS Keep It Simple.

18hp electrical.pdf

[roger56]

Throttle is controlled by cable Back to steering area. It has diconnect at the motor. When disconnected you can operate with twist grip.
I plan to repair the wire problem with new wire after testing the wires back to the switch.