1970 60hp running rich

[thegipper]

My 1970 60hp Johnson appears to be running too rich. My issues are:

It's seems to "load up" when it idles for a long time and struggles to stay running like when you are trying to dock or maneuver at very low speeds. This is basically where 95% of my problem is, low speed maneuvering going between forward/neutral/reverse.I don't think that the idle is too low as I've tried turning it up a bit but have the same problem.

When I pulled the plugs, all three are pretty "wet" with oil/gas. Plugs are only a year old and otherwise appear to be fine.

Compression tests are 120, 117, 120 (top to bottom). Gas is mixed at 50/1 regular 87 octane.

Spark easily jumps 7/16" gap on all three wires.

When I accelerate, it often feels like it bogs down for a second or two and you can feel when it "jumps back" to life, almost like a small jolt.

At half to full throttle, it runs great. It pushes my 16.5' Starcraft about 30mph at WOT. It also starts very well, usually on the first or second crank.

Can the carbs be adjusted to not run so rich at idle? If so, how do I do it? I do have the factory service manual (somewhere, need to find it) but I'd thought I get some opinions before I start messing with stuff.


Thanks guys!

 

[Tourtney]

Do you have any additives in your gas like sea foam? If they were getting badly fouled up you’d have to clean them dry after stopping at idle to start it up again. But to answer your question, there is an idle speed jet at the top of each carb, turning it in will make it run leaner. I have a similar engine and I set mine out 3/4 from gently seated and I believe that is typical as written on the sticker for the engine. Make sure throttle plates are completely closed at idle.

 

[F_R]

As soon as I read "1970 60hp Johnson", I automatically jump to conclusions, which is bad, so sorry 'bout that. But anyhoo,, the automatic conclusion is spark plugs. If it still has the original surface gap plugs, remove them and drop them in the deepest hole in the ocean. Those things wouldn't run in 1970 and they won't run now. Replace them with Champion L77JC4 or QL77JC4

 

[thegipper]

It has the JC4 plugs already. No additives in the fuel, just straight gas and marine 2 cycle oil.

Ill check on the throttle plates and see how the jets are adjusted.