1973 Johnson

[lemrac]

1973 Johnson 9.5 model 9R-73B <br />Compression 60lb both cylinders,plugs look good, points look good, coils look good, but no spark either cylinder. Any suggestions? Can't afford new motor.

 

[DHPMARINE]

Re: 1973 Johnson

lemrac,<br />Lots of things to do to try to get your spark back.<br />BUT 60PSI is too low.I don't try to fix an outboard with less than 70PSI.And those don't always pan out.<br />Maybe pull the cylinder head off and inspect things.If all looks good,reinstall the head with a new gasket,and if compression comes up,then pursue the spark problem ?<br /><br />DHP

 

[JB]

Re: 1973 Johnson

I am inclined to call the compression okay because they are equal. Differences in guages and technique can easily make a rope start engine with acceptable compression read that low.<br /><br />The spark: I think all of the 9.5s had magneto ignition. With neither plug making spark I would be tracing the kill switch wires because that, the flywheel and the points cam are the only things that the two magnetos have in common and it is almost dead certain that one of them is the culprit.<br /><br />Pull the flywheel and look for anything that keeps both sets of points at ground even when the points are open. Look for a sheared flywheel key or a damaged points cam.<br /><br />Let us know what you find, and good luck.

 

[SportfishermansSVC]

Re: 1973 Johnson

I agree with JB on the compression issue and testing. There is no set number that the compression should be set at. We routinely see motors that have 40 or 50 psi per cylinder that run beautifully. The more important information is the ratio between the cylinders. <br /><br />Good Luck

 

[lemrac]

Re: 1973 Johnson

Thanks for the help,I will try some more and post results. Thanks again, lemrac

 

[P51D]

Re: 1973 Johnson

I know this is an old post, but I also have a 1973 9.5, with compression in the low 60's on both cylinders. And it runs beautifully at all speeds, including up to the rated RPM's.<br /><br />Lemrac - did you find the problem?