84 Evinrude 9.9 best spark plug?

merkdawg0084

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Oct 11, 2017
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Hello, I have a 1984 Evinrude 9.9. My issue is that I boat on a lake that is idle speed only! It seems to do fine, but when I get home and lower the motor in the straight position I have some oil dripping out of prop? Is this normal? Too rich, too lean? Hotter plug? I’m using the plug that the manual calls for? Thx
 

Vic.S

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May 4, 2004
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The currently recommended plugs are QL77JC4 or QL82C, gapped at 0.030"

It is usual for some unburnt oil to drip from a 2 stroke This will be more if the engine is only used at low speeds.
The recommended fuel mix is 50:1 but you could safely reduce the amount of oil for your low speed use if this is a problem. Dont go beyond 100:1 and either fog the engine before prolonged non-use ( winter lay up) or run 50:1 for the final outing.

If / when you can give it a good thrash at high speed or you will get excessive carbon deposits in the engine

Make sure the carb low speed needle is correctly adjusted
(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

A electric outboard would probably be more suitable for your use ........ One of the Torqeedo models if they are available in your part of the world.
 

racerone

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Dec 28, 2013
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Running at 100:1 is a mistake.----Run at 50:1 all the time.-----Perhaps check the recirculation system / circuit as the wee screen might be plugged !!
 

JimS123

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Jul 27, 2007
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I just answered this same question - re. optimum tuning kicker.

* replace the plug with a SplitFire - cross reference to oem spec L77...
* use XD-50 oil
* replace the prop with a "sailboat prop" - i.e., lowest pitch available.
 

merkdawg0084

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Oct 11, 2017
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Thx for the replies. And yes Racerone I would never run a 2 stroke at 100:1. I do try to open up the throttle when no one else is around. Lol. It is pumping water. Thx
 

racerone

Supreme Mariner
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Dec 28, 2013
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On the plate with the reed valves.-----Parts list does not show it in the right location.-----Every one of the 20 or more of these motors in my cluttered workshop have this screen !
 

CatTwentyTwo

Chief Petty Officer
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Jan 11, 2005
Messages
425
I'll be darned, I learned something new today. I had no idea these motors had something like that.
Thanks again.

Edit, Can the gaskets be reused or is it best to buy new ones before tearing into this?
 

racerone

Supreme Mariner
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Dec 28, 2013
Messages
38,898
You might be able to re-use the gaskets.-----But check the groove / channel that oil takes to get to the top bearing.----And check the check valve too.-----This stuff is really simple in my opinion.
 
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