56' evinrude 15 hp

raymondmoyer

Seaman
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Aug 20, 2003
Messages
73
I am the proud owner of a low hour 1956 evinrude 15hp. I have rebuilt the carb, replaced coils, plugs, and the impellar.the motor runs well at high speed,and pumps plenty of water. The lower unit oil wasn't murky when I drained it, and there are no signs of leaks anywhere from the lower unit. I have a problem when idling, the motor tends to jump when you slow to an idle. By jump I mean it feels like it is slipping in and out of gear. Could this be the happening ? If so how can I go about fixing this problem ? Thanks for all the help this sight is great. :)
 

Chinewalker

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Aug 19, 2001
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8,902
Re: 56' evinrude 15 hp

Hi Raymond,<br /> Is it a thunking, mechanical "jump", or a sneezing kind of "jump"? If it's a mechanical sound, then it may have an issue with the clutch dog, but that generally manifests itself at higher speeds - you said your high speed running is fine. If it's sneezing, then you've got some adjusting to do with the low-speed idle mixture. Motors will sneeze when they're running lean, so you'd want to richen up the low-speed needle valve a hair. Might even be a smidge of junk/gunk in the carb that got missed the first time through. Compressed air might help blow it out...<br /> Great old motor...<br />- Scott<br />
ScottEv151982.jpg
 

rwise

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Jul 5, 2001
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3,205
Re: 56' evinrude 15 hp

Dude, put remote in that and you got my boat!
 

raymondmoyer

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Aug 20, 2003
Messages
73
Re: 56' evinrude 15 hp

Thanks for the quick response chine walker. That is the motor. Except I got the kid by about two hundred pounds or so :D The previous owner painted it completely black for some odd reason. I'll deal with that after I get everything squared away mechanically. It's a mechanical thunking, the whole entire motor jumps. You can see the motor move. It only happens at a low idle. The motor shifts fine in both forward, and reverse. I completely stripped the carb apart, soaked it in carb cleaner for two days ( still had fuel in the bowl from who knows how long ago ) Blew everything out with the air compressor before re-assembling. I also changed all fule lines at the same time just to be on the safe side.Then after reassembly I decarbed with seafoam boy my neighbors loved me for that one :D but on the bright side I killed every flying insect for a two to three block radius :D I'm going to pull the lower unit and have a look around and see what I find. Thank you again sir :)
 

SCO

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Aug 19, 2001
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Re: 56' evinrude 15 hp

Chinewalker is right on I think. I have a johnson 18, 1958, looks just like yours. It sneezes at low speed too when it first starts, and stops when warm. That is by design because I adjusted the low speed idle to just above that sneeze point with the engine warm(am I too lean Scott? ) . When it sneezes it jumps and almost dies. MAybe the sneeze is a backfire, but it looks/sounds just like a gear clunk, but the lower unit is not involved, and richening the low speed idle jet will stop the sneeze. The next time I take it out I will probably richen the low speed to avoid those initial start up sneezes.
 

Chinewalker

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Re: 56' evinrude 15 hp

Hi Raymond,<br /> Here's a test - does the ka-chunking stop when the motor idles down in neutral or does it keep doing it? Does it ka-chunk in reverse, too? If it does it in either reverse or neutral, then it's gotta be fuel related. Maybe richen the high speed a hair, then richen the low speed. Neither needle should be more than 2-full turns from closed.<br /> By the way, that pic was taken about 200-lbs. ago and 25 years ago. Dad was playing around with Black-N-White film at the time and snapped that one...<br /> SCO - it sounds like you've got your 18 adjusted right. If the motor absolutely will not get rid of the sneeze, it may be an indication that either the upper or lower main seal is going bad. The motor then sucks air in through that rou;te and creates an artificial lean condition....<br />- Scott
 

raymondmoyer

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Aug 20, 2003
Messages
73
Re: 56' evinrude 15 hp

It will do it in neutral, forward and reverse.I'm getting ready to head to the river right now. I'm going to take the motor along and adjust the mixture screws and see if that has any effect on it. I'll let you know what happens. Once again thank you all. I don't know where I would be without this board. :)
 

SCO

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Aug 19, 2001
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1,463
Re: 56' evinrude 15 hp

Dont overtighten. Only need to look at low speed jet, ccw. I think it is the bottom one isn't it?
 

raymondmoyer

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Aug 20, 2003
Messages
73
Re: 56' evinrude 15 hp

Nah the low speed is the top screw or the smaller one. Thanks for the help guys, turns out I'm just a moron :D . I got a hold of a new tiller handle Friday. According to the labels on the handle, it idles fine. The throttle is below the idling mark when it starts to cut out on me. I'm taking that too mean, that when the knlunking noise occurs the motor is idling too low to stay running. Once the throttle is set to the idle position everything is a okay. This sound right ?? Thanks for all your guys help. :)
 

Joe Reeves

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Joined
Feb 24, 2002
Messages
13,262
Re: 56' evinrude 15 hp

Raymond.... If that ka-chunking takes place in neutral, It really could not be a jumping out of gear ka-chunking. I suspect that it is rather a mild backfire type effect that is caused by either a fouled carburetor which needs cleaning and rebuilding.... or a carburetor that is out of adjustment.<br /><br />The proper adjustment procedure follows, and hopefully is of some help to you.<br /><br />(Carburetor Adjustments - Two Adjustable N/Vs) <br />(J. Reeves)<br /><br />Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns. <br /><br />Setting the high and low needle valves properly: <br /><br />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.<br /><br />(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. <br /><br />(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. <br /><br />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.
 

raymondmoyer

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Aug 20, 2003
Messages
73
Re: 56' evinrude 15 hp

Thank you very much sir. I had read somewhere on here where you posted that previously. I adjusted the carb this weekend exactly per your instructions. That and the proper markings on the tiller handle have taken care of my problems. My baby is running like a top now. Thank you guys so much for all the great help. Now it's time to strip the black paint off and restore it too it's original colors. :)
 
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