Mercury 9.9hp 2 cycle questions

[Michigander]

Looking forward to connecting with someone who has experience with old Mercury 9.9 2 cycle outboards.

I have a 1988 Mercury 9.9 two cycle motor, s/n OB337317. The motor was given to me by a neighbor who said it was setting for years in his garage but ran good when he last used it 10 years earlier. It was seized when I got it ... but after several weeks of applying penetrating and Marvel Mystery Oil , I finally got it to turn freely and a compression test reads 85 psi.

FIRST QUESTION: Does anyone know if that's enough compression to start the motor?

There was no spark so I installed a new $40 ignition box and now have good spark.

When I tried to adjust the carburetor, the brass adjustment screw which was seized, snapped off. A new carburetor (#1392-8846A24) is no longer available, and a used carb with the correct part number is extremely scarce and very expensive. However, I see reasonably priced knockoff carbs on eBay for Mercury 9.9 two cycles that are for different serial numbered motors than mine. A friend says they won't work.

SECOND QUESTION: Does anyone know if any of the cheap replacement (knockoff - $30 to $40) carburetors for different serial number motors that are advertised on eBay would work on this motor?

Also, the reeds are also shot but are available at a reasonable price.

THIRD QUESTION: In your opinion, with the information shown above, is it worth spending the money in an attempt to get this motor running or should it be added to the scrap metal pile?

Any advice would be welcomed. Thanks

 

[KnotYet]

The compression should be good enough to start it; 2-strokes are low-compression.
Since you already bought the coil you might as well keep at it.

Have you tried to use the carb you have? If it isn't useable, here's one for $126.
https://www.ebay.com/itm/3949996382...MI8LqTvOuMgwMV-jStBh0pXQsqEAQYBCABEgJZ2vD_BwE

The older, 2 stroke outboards get praise for being simple and lightweight for the power.
Michigan should also have a wealth of used outboards for sale and repair shops, too.

 

[Michigander]

Thanks, I may try some of the different local shops in our area. I especially appreciate your comment about the compression. I was not sure if 85 psi was even enough to get the engine started.

 

[Mischief Managed]

I think the 1986 through 2004 9.9s are pretty much the same, so a newer part number carburetor may work. I have a .pdf of the factory service manual, feel free to IM me and I'll email it to you.


For those years, the 6, 8, 9.9 and 15 HP engines are all identical except for the carburetor throat diameter. I installed a 15HP carburetor on a 2004 9.9 and it made a substantial difference in power. I used part 1392-9726T18. Sadly, I gave away the old carburetor...

 

[SteveK]

I would remove the carb and take it to the parts store and compare mounting holes, linkage points. Back in the good old days, the parts guys would look at a part not available by part # and walk to the back to pick up one with a different part number.