Re: 9 1/2 hp Johnson will not run
Re: 9 1/2 hp Johnson will not run
Ethomas.... Depending on how fast you crank that engine over, the compression should be approximately between 75 and 100 psi. The important thing is that the compresion reading should be even on both cylinders.<br /><br />With the s/plugs removed, check the spark. The spark should jump a 1/4" gap with a strong blue flame.<br /><br />If the above checks out okay, I suspect that the carburetor is somewhat clogged. In which case the cure would be to remove, clean, and rebuild it.<br /><br />The proper carb adjustment is as follows:<br /><br />(Carburetor Adjustment - Single S/S Adjustable Needle Valve)<br /><br />Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.<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 />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
What should the compresion be?