How to adjust carburetor?

jwyler

Cadet
Joined
Aug 2, 2005
Messages
22
Hi,<br /><br />I realize this may be a common question on this board, but I haven't found the help I need from a search...<br /><br />I have a 1956 Evinrude 15HP. Just removed and cleaned the carburetor. Now I'm wondering how to adjust the lower and upper needles once it's set up again. The Clymer manual provides a procedure that requires a tachometer, but I'm looking for a more approximate trial-and-error approach. Without know what I was doing, I messed around with the needles over the past year while the motor was running, and never noticed any effect.<br /><br />(Also, it's difficult to find the fully-in position of the lower needle -- it ends up being in a different place depending on whether or not the tube it fits in is fully seated, which is to say the o-ring seal seems to expand and lock up the needle screw before it's all the way in.)<br /><br />Thanks for any tips, --Jon
 

OBJ

Supreme Mariner
Joined
Dec 27, 2002
Messages
10,161
Re: How to adjust carburetor?

Here is a proceedure by Joe Reeves Jon. It's for a 7.5 but will work for 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 va /lve 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, wating 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.
 

jwyler

Cadet
Joined
Aug 2, 2005
Messages
22
Re: How to adjust carburetor?

Am I likely to have any trouble starting the engine at the initial settings? If so, what to do? Thanks for the info, --Jon
 
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