Re: Johnson 18 hp, not used in years, what should I check for before starting
Jeff... An FD18 is a 1964 18hp Johnson. Check the gear lube, uses HiVis (80/90w) lube available at K-Mart, Wal*Mart etc. If a philips screw exists in the lower unit skeg, DO NOT remove that screw as it would be a pivot point shoulder screw for the shift linkage.<br /><br />You may safely use a fuel/oil mixture of 50/1 on that engine as it has all needle and roller bearings on the moving parts. (1pt 50/1 oil to 6gal gas). A fuel rating of 87 octane will be fine.<br /><br />With the s/plugs out, check the spark, should jump a 1/4" gap on both cyls with a strong blue flame. Use Champion s/plugs with the gap set to .030 .<br /><br />Check the compression, should be in the range of 80/100 psi and even on both cyls. If you have no gauge, with the s/plugs installed, pull the engine through a few times to get a general feel of how the compression rates.<br /><br />Remove, clean, and rebuild the carburetor. After sitting that long, there is no question that the carb is fouled. Purchase a carburetor kit at your local dealership or at NAPA, etc. Running an engine with a fouled carb will have the engine running lean on its mixture, and this will cause piston damage etc. (Don't want that).<br /><br />When you're finished with rebuilding the carb, adjust it as follows:<br /><br />(Carburetor Adjustments - Two Adjustable N/Vs) <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.
