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Carburetor Adjustment Johnson V4 115

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  • Carburetor Adjustment Johnson V4 115

    I recently purchased an old (1969) Boston Whaler from a friend and it has a 82 Johnson on it. The boat had been sitting for 3 years, The engine was not running but I found where a coil wire had broken and after I replaced it the boat fired up. When I tried to run it it was like it wanted to start planing but it couldnt get enough gas. I then ran all new gas lines, filter, and cleaned the carburetors out with spray and stuffed rags in the 4 carburetor holes. The boat now runs very fast and idles high when it is hooked up to a hose. I need to know how to adjust it so that it will idle a little slower. There are little screw looking things at the top of all four holes after you remove the cover plate but i am unsure if these are what i should mess with.
    How can I get it running at a better speed? Where do I adjust teh carburetor to idle at a lower speed? Also, I've changed the lower unit gear lube, is there anything else I should look at b4 putting the boat in the water?

    Thank you in advance,


  • #2
    Re: Carburetor Adjustment Johnson V4 115

    On a flushette, that engine should idle at 1000 rpm.

    (Dual Carb V/4 With 4 (2 each carb) Slow Speed Adjustable N/Valves)
    (J. Reeves)

    The adjustment procedure of the carburetor slow speed needle valves follows. NOTE... if the needle valves turn too freely, replace the nylon bearing retainer (the nylon item at the front of the carb that the needle valve goes through first) with the newer type RED retainer #315232. If your engine has that weird linkage that connects all four of those needle valves, the newer RED retainers will enable you to discard that linkage. The RED retainers make it impossible for the needle valves to vibrate out of adjustment.

    (Carburetor Adjustment - 2 Slow Speed Adjustable Needle Valves, each carburetor)

    Initial setting is: All (4) Slow speed valves = seat gently, then open 1-1/2 turns.

    Facing the carburetors, start with the top left needle valve, then the top right valve, then the bottom let valve, then the bottom right valve. It may be necessary to redo these steps to get the adjustments ideally set

    Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S 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 (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

    Do not attempt to gradually adjust all four of the valves at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve.

    When you have finished the above adjustment, 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.
    Our Questions Require Answers... If You Refuse To Answer Our Questions... How Can We Answer Yours?


    • #3
      Re: Carburetor Adjustment Johnson V4 115

      Mr. Reeve's,
      Thank you for your help, it is greatly appreciated.



      • #4
        Re: Carburetor Adjustment Johnson V4 115

        Mr. Reeves,
        They do not turn too freely but I dont really have anything to go off of to tell if they are. Where would I get those parts to replace these bearings? Also,
        I think the throttle needs to be tightened where would I look to make that happen?

        Thanks again


        • #5
          Re: Carburetor Adjustment Johnson V4 115

          The needle valve bearings (bushings)...... If they are RED in color, you have the new type (tight ones). If in doubt, purchase the new RED 315232 ones at any dealership.

          Throttle tension..... depends on the type of control box. If the OMC white box, there should be a tension adjustment on it somwhere.
          Our Questions Require Answers... If You Refuse To Answer Our Questions... How Can We Answer Yours?


          • #6
            Re: Carburetor Adjustment Johnson V4 115

            This boat has sat for 3 years so I'm sure I will keep running into problems here and there but it seems like none of this is too hard to fix as long as you are willing to learn and soak in the knowledge of others.

            When I went to change the lwoer unit gear lube it came out a grayish color. I assume this is because water had gotten in but is it for certain that it has a leak or could it be from sitting for so long through this South Mississippi weather year in and year out?? How can I tell if I need to repair the lower unit? The magnet on the lower screw had very tiny shavings of metal but nothing that didn't seem like it should be there.

            Also, do I need to service the water pump on this thing? It shoots/sprays water out fine when running in water and on the hose is there a way to tell if it needs servicing?

            Can you think of any other preventive things I should do to try to curb the problems that could arise out of this motor?

            Thanks again Joe!


            • #7
              Re: Carburetor Adjustment Johnson V4 115

              Small fuzzy like metal particals on the drain plug magnet are normal. Not normal would be metal chips, splinter like slivers, obvious chunks of metal that has broken off of some inner component.

              A grayish white appearance of the gear lube would indicate that water has somehow entered the gearcase. Drain it and fill the gearcase from the bottom drain hole until it flows out of the top oil level hole. The unit uses what is called HiVis 80/90w gearlube, available at Wal*Mart, K-Mart, various marine type stores, probably NAPA, and of course at your dealership. I'd suggest you buy a couple quarts which will allow you to have some on hand after filling the unit. If the lube again turns grayish white, check for leaks as follows.

              (Checking Gearcase For Leaks)

              Remove the large slotted drain/fill screw from the bottom of the gearcase and also the identical looking screw that will be located up near the cavitation plate in order to drain the gearlube.

              After all of the lubricant has drained, install one of the slotted screws, whichever your preference might be.

              Apply 7 to 12 pounds of air pressure to the open screw hole. Use a piece of rubber fuel line or something to create a tight air hose fit if you do not have a proper fitting.

              If a leak exists, that pressure should allow you to locate the leak by sound and/or sight.

              If the plugs have a "worn at an angle" electrode, replace them with Champion QL77JC4 plugs, gapped at .040 (original recommended gap) or .030 (revised gap in 1990s). Try both to see if a improvement exists with one or the other.

              Carburetors.... sitting that long, they probably need cleaning and rebuilding, using new carb kits, available this site no doubt and others locations, NAPA etc. However, give the engine a try out in the water. If the water test reveals a lack of power or some other questionable trait, we can take it up from there.

              Use a 50/1 mixture..... 1pt of TCW-III 50/1 oil to 6 gallons of gas. A octane rating of 87 will be fine.

              With plugs removed, spark should jump a 7/16" gap with a strong blue lightning like flame.... a real SNAP!

              Good luck.
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              • #8
                Re: Carburetor Adjustment Johnson V4 115

                I think you are correct about the carburetors needing cleaning. When I got her in the water she seemed to be idling fine but when I would try to get her going she would act like she wanted to go and then start dying down and sputtering when I tried to get her more gas. She would go fine at about 5 miles an hour but once I tried to plane her out she would act like she wasnt getting enough gas. where can I get directions on how to rebuild these carb? I have ordered the repair manual and 2 carb kits.




                • #9
                  Re: Carburetor Adjustment Johnson V4 115

                  Directions would be via a service manual. However, the carburetors aren't complicated. Make notes, take pics before and while dismantling and you'll be fine.
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                  • #10
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                    Re: Carburetor Adjustment Johnson V4 115

                    Joe I appreciate you taking the time to help me out. I have attached a few pictures. I need to get a steering arm for this thing (if that is possible). I have it pictured in the second picture but it may be hard to see.
                    Attached Files