Re: Evinrude Mystery Model no 115093D
Storskar.... Assuming that the compression and ignition (spark) are okay, the answers to your questions:<br /><br />(You)"Everything is fine at low revs and idle but as i throttle up the engine "studders" and refuse to rev up. Spark plugs wet and black." <br /><br />(Me) Sticking timer base under the flywheel or fouled carbs. Carbs may simply be out of adjustment. Try adjustments first (listed below).<br /><br />(You)"Absolutely guzzles petrol!!! 55 litres gone in a whiff!"<br /><br />(Me) Same answer as above.<br /><br />(You)"What oil mixture (1:50?) and octane (98 unleaded)"<br /><br />(Me) Use the 50/1 mixture with 87 octane unleaded.<br /><br />Now, to adjust those carbs.....<br /><br />(Dual Carb V/4 With 4 (2 each carb) Slow Speed Adjustable N/Valves)<br /><br />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 viberate out of adjustment. <br /><br />(Carburetor Adjustment - 2 Slow Speed Adjustable Needle Valves, each carburetor) <br /><br />Initial setting is: All (4) Slow speed valves = seat gently, then open 1-1/2 turns. <br /><br />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 <br /><br />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. <br /><br />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. <br /><br />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. <br /><br />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.
