1975 9.9 sea horse

jimmbo

Supreme Mariner
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May 24, 2004
Messages
13,096
Turning the Throttle down, retards the timing, which is how the Idle Speed is set. If retarded too much the engine will die. The carb, is fully closed at idle. 1 1/2 turns out from lightly seated is where the Idle Mixture Screw, is initially set, and is adjusted once the engine warms. Final setting is usually leaner. Idle speed is about 600-650rpm, in gear
 

Garner51

Seaman Apprentice
Joined
Jul 12, 2023
Messages
41
Turning the Throttle down, retards the timing, which is how the Idle Speed is set. If retarded too much the engine will die. The carb, is fully closed at idle. 1 1/2 turns out from lightly seated is where the Idle Mixture Screw, is initially set, and is adjusted once the engine warms. Final setting is usually leaner. Idle speed is about 600-650rpm, in gear
I’ve got it running what I would consider decent but y’all give me y’all’s input. What spark plugs do you suggest and my gas ratio is 50:1 why so much smoke when I throttle up all the way then back down is it because the plugs can’t burn it? Or?
 

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racerone

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Dec 28, 2013
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36,670
Oil is put into the gas to lubricate the internals.-----Oil inside the engine is constantly replace with clean oil.----But oil in the gas is a big mystery for many folks.
 

Garner51

Seaman Apprentice
Joined
Jul 12, 2023
Messages
41
Oil is put into the gas to lubricate the internals.-----Oil inside the engine is constantly replace with clean oil.----But oil in the gas is a big mystery for many folks.
? That’s the purpose of it right? My question is everything seems to be done to spec with leeroy and with you guys, it’s just smokes like that when I decelerate would a change in plugs help? if so what type? Or is the lean rich maybe out but once again thank all of you for reviving this motor and getting it back in the water.
 

jimmbo

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May 24, 2004
Messages
13,096
The Sweet Smell of TCW, is one that I Cherish. The more smoke the better, keeps the Skeeters away
 

OptsyEagle

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Sep 13, 2006
Messages
1,356
It is always a little more smoky when it is running in a barrel without a load. You will find it will leak out some of that black unburnt fuel/oil/carbon after a lot of barrel running. Again, very normal and it does not happen as much when run on a boat.

The best spark plugs for that motor are NGK B7HS. The recommended champion plugs will foul much quicker so use the NGKs. Also, don't use that motor for multi hour trolling or plan to change your plugs more frequently, no matter what spark plugs you use. That motor is hard on spark plugs when it is run slow but it loves to run wide open throttle, full out. If you do run it slow, open it up before you come back to the dock/launch to burn off some of that carbon build up.
 
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