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Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

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  • Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

    Hi all! I just finished rebuilding a '57 Johnson 3 hp. Starts up fine and runs at higher speeds great after adjusting the high speed valve. But it just dies as soon as the lever is put left of START. I've played around with the low speed needle (starting at 1 1/2 turns off seated) without much progress. The engine will run at lower rpms if i play with the carb while on the start position, but sliding toward slow at all kills it no matter what.
    Rpms do increase as i turn it in but as soon as i take the throttle down a little the engine cuts off at the same point every time. The carb has a whole new kit and has been disassembled and cleaned twice now. The low speed valve had an even taper but did look a little worn. (have one on order). Would this cause my problem? Or is it the jet? Carb cleaner flowed freely from the needle valve inlet to the little hole coming up from the float bowl.

    Fuel was fresh, new plugs, wires, points (set .020), condensers, all new gaskets and deglazed cylinders with new rings. no fuel leaks around carb or anything like that.

    Thanks to anyone who takes the time to respond.


  • #2
    Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

    When you rebuilt her did you clear the three tiny orifices in the carb throat? You need to remove a Welch plug in the top to get at them. There is a replacement plug in the kit. Those are often overlooked or simply blown with air.
    sigpic

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    • #3
      Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

      Is this right after the rebuild? Has it been broken in yet?
      Chris

      Top Secret Files:

      http://forums.iboats.com/showthread.php?t=299680

      Comment



      • #4
        Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

        Originally posted by JB View Post
        When you rebuilt her did you clear the three tiny orifices in the carb throat? You need to remove a Welch plug in the top to get at them. There is a replacement plug in the kit. Those are often overlooked or simply blown with air.

        That's the only part i didn't replace with the kit. i lost the plug that came with the new kit, but figured the motor ran and idled nice and slow before i stripped it down so i thought i'd be ok. i ordered another kit yesterday just for the plug because it was on my mind. the rebuild came about because the head gasket blew and i figured it was from poor water circulation, which it was, plus the piston rings were way out of tolerance. maybe some of the old needle valve packing got stuck in the jet when i picked that bugger apart trying to remove it.

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        • #5
          Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

          Originally posted by HighTrim View Post
          Is this right after the rebuild? Has it been broken in yet?

          yes, high trim. just finished putting back together and was running it in the barrel for initial adjustments. (lakes are still frozen over in wisconsin). plan on starting a proper break in under load in a week or two. should i run it a bit more in the barrel as low as i can for a while longer? its my first rebuild and first outboard.

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          • #6
            Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

            Yes, you may not be broken in enough to idle down. Just my guess. May have nothing to do with the carb rebuild at all.

            Disclaimer: The discontinued the penny up here in Canada, so my 2 cents doesnt buy much anymore.
            Chris

            Top Secret Files:

            http://forums.iboats.com/showthread.php?t=299680

            Comment



            • #7
              Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

              What are your compression numbers post rebuild?
              Being cheap and not getting a manual will cost you hundreds or maybe thousands of dollars

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              • #8
                Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

                Will do High Trim. I'll keep easing her back to life a bit more. If nothing improves I'll take up JB's advice and clean out under that plug once i get the new one. Thanks to both of you guys. Will report back in a week or so hopefully with good news.

                Comment



                • #9
                  Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

                  Compression is just between 85 and 90 on both cylinders now. before the rebuild i was getting barely 70 on 1 and just over 60 on 2.

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                  • #10
                    Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

                    That is pretty good for a JW. Really good.

                    What type of sealer did you use on the crankcase halves? New spaghetti seal?
                    Chris

                    Top Secret Files:

                    http://forums.iboats.com/showthread.php?t=299680

                    Comment



                    • #11
                      Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

                      Have you synced your armature cam and carb. cam follower properly? Best of luck. Rick.

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                      • #12
                        Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

                        No spaghetti seal on the '57, High Trim. Just glued the halves back with permatex flange sealant. (equivalent to loctite 518)

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                        • #13
                          Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

                          Rick, not quite sure what you mean. there only seemed to be one way to reassemble with the holes all lining up. Are you referring to that notch in the circular piece that the ignition plate screws to (under the wave washer)? that notch lined up with the key on top of the block facing the carb, right?

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                          • #14
                            Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

                            Oh wait, Rick. You mean the black curved piece under the throttle lever that engages the throttle linkage when placed in the START position? If so, then yes i believe it is in sync. At least it seems to be in the same place as before I took everything apart.

                            Comment



                            • #15
                              Re: Rebuilt Johnson JW13 wont idle. Worn low speed needle valve?

                              Originally posted by Shaner81 View Post
                              Oh wait, Rick. You mean the black curved piece under the throttle lever that engages the throttle linkage when placed in the START position? If so, then yes i believe it is in sync. At least it seems to be in the same place as before I took everything apart.
                              Yes that was what I was referring to. Have a look at this thread. High Trim helped me with this a week ago. Not sure if your set up is the same. Rick.
                              http://forums.iboats.com/johnson-evi...ng-596500.html

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