1965 3.9hp plug fouls

Teseal

Seaman
Joined
Aug 2, 2018
Messages
63
OK so going to run on the J8C for now. Still running way to rich it seems, lots of smoke and oil in the water. Waiting for a service manual now so I can check carb/ign sync and timing.
 

merc850

Commander
Joined
Jul 7, 2010
Messages
2,046
I don't know what brand of oil you're using but I've found that Amsoil synthetic smokes less and if you live in the US you can get 100:1 blend which lets you go from 50:1 to 100:1. I was mixing it at 70:1 and of course I used less oil and reduced smoking.
 

Teseal

Seaman
Joined
Aug 2, 2018
Messages
63
That ratio info is pretty interesting. I don't remember the brand of oil just that it's the correct spec, marine, and in a blue bottle. But I don't feel my Yamaha 40 smokes a lot nor all the other 2 cycles I use it in. But you know another thing that concerns me is all the oil in the test barrel.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
37,970
Oil in a test barrel is a concern to many folks.-----I have stated it many times.----Oil / lubrication / operation / inner workings of 2 strokes is not well understood.-----Oil floating in your test barrel is normal for that motor !
 

Teseal

Seaman
Joined
Aug 2, 2018
Messages
63
I agree, I expect to find some oil floating in there. The quantity is what is concerning me, especially after such short runs. Its not the first 2 cycle I've run in a barrel.
 

Teseal

Seaman
Joined
Aug 2, 2018
Messages
63
My apologizes for not following up sooner, kinda forgot. Here’s where it ended up. During the original maintenance before attempting to start it had a good spark by spinning the flywheel by hand so I did not look into the ignition. After everything we’ve been thro I felt the only thing creating the unusual amount of residue in the tank could be because it was running way more inefficiently than normal at the low rpm, possibly even missing creating the “sputter” I mentioned at low rpm. Even tho it appeared to have good spark I could not be sure it wasn’t missing which could have created the excess oil. I replaced points and condenser and things changed. The sputter at low rpm was drastically reduced, higher rpm was smooth and didn’t seem to change. No idea how mechanical points or the condenser would seem to have a problem at low rpm and not high ???? I did not clean the tank and retest to see how much oil would be present. It starts good, actually it always did, idles good, accelerates smooth, and blows the water out of my test barrel. As they say in the manufacturing world, “ship it”.

Thx everyone for your inputs and any finial thoughts.
 
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