Mariner 9.9 project

[burnt clutch]

So I got this outboard from my neighbor. From what I can tell it’s a 1978 or 1979 Mariner built by Yamaha.

I tried to do a compression test on it and I got 55PSI out of the top cylinder but the starter rope frayed really badly after the 3[SUP]rd[/SUP] pull when testing the bottom cylinder so I really couldn’t get a reading on it. My question is – what is the usual fix for low compression on these? New rings and or pistons and upper/lower case seals, or is there more to these engines than that? I haven’t tested the coils yet, but if I need one are there new coils out there that retrofit to this type of engine? Lastly are these good engines worth tinkering with? What are their strong and weak points? I’m new to the outboard scene, all I’ve really messed with is my Johnson TN28.
Thanks in advance for your inputs!
-Karl

 

[burnt clutch]

Here are some more pictures.

 

[racerone]

Use electric starter to do compression test ?---Remove recoil and wrap rope on flywheel to complete the compression test.--Crankcase seals have nothing to do with compression in the cylinder.------These are a very well built motor and worth fixing.-----Parts are available at Mercury dealers.--And why has everything been cut on this motor ?????

 

[burnt clutch]

I'm gonna follow-up with hot wiring the starter and trying the compression test again. My neighbor is all thumbs with anything mechanical so its anyones guess as to why this thing is as botched as it is. I'm just thankful that he didn't straight gas it. I'm a little concerned about the missing choke linkage and the cut sparkplug boot. Did these engines change much through the years and would the choke linkage be hard to find?

-Karl

 

[undone]

The fix for low compression is a total rebuild, it doesn't make much sense to tear it down completely and not replace all the parts that wear out.

They run well and should be repaired and will run for a long time. The problem is if much work needs to done it can easily cost more than the value of the motor, you can frequently buy a much newer and good running motor for less than the parts needed to rebuild it.

That's assuming it has low compression, if the compression is still good the repairs shouldn't cost much.