1989 Johnson GT 150 Carb Clean/Rebuild Question

Westley Wood

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Joined
Dec 4, 2017
Messages
6
I have a 1989 Johnson GT 150 that has been sitting about 8-9 years without being cranked. I am going to change all the fuel lines and clean carbs along with change all the gaskets, etc. I have cleaned and rebuilt several single carbs on smaller outboards, but have never rebuilt carbs on a multi-carb engine. My question is...if I unhook the linkage and reconnect exactly as it was, along with setting all carb settings exactly as they were before cleaning, what type of issues will I still run into with the carb settings, idle, mixture, etc. Thanks in advance for your input.
 

spybot

Chief Petty Officer
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Jul 4, 2016
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504
It may work but i think you will be better of doing a Link & Sync once you have them back on the motor.
 

Joe Reeves

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Feb 24, 2002
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13,262
Link & Synchronization.... Rocket Science mentality not required.

Assuming you have not changed the linkage distance between the vertical throttle arm and the cam. (Idle Timing)

1 - Back cam away from the throttle roller.
2 - Check linkage between the carburetors if needed to make sure that all throttle butterflies open and close at the same time. You DO NOT want one butterfly ever so slightly open and the other(s) closed.
3 - Adjust the throttle roller so that the butterflies just start to open when the scribe mark of the cam is dead center with the center of the throttle roller.
4 - That's it!

Note that the roller should be approximately 3/8" in diameter.... Should it be a two piece roller and the outer portion has broken off, it will be roughly 1'8" in diameter, in which case, replace it.
 

Westley Wood

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Dec 4, 2017
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6
Hi Joe, I have two scribe marks on the cam. One is long and one is shorter. I assume I line it up with the longer one, as the shorter mark seems to be on the edge of the cam??
 

Westley Wood

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Dec 4, 2017
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6
Also, I do not see any type of fuel mixture adjustments on any of the carbs. It is my understanding that these carbs have no adjustments other than the float. Is that correct? Thanks
 

tommarvin

Ensign
Joined
Nov 22, 2015
Messages
999
Disconnect and reconnect exactly,the same
The carb settings will be for example one and a half turns out after gently touching not sure about your carbs.
You should watch all the you tube vids on carb cleaning,don't just watch one and go for it,I learn something watching every video.
For some reason carb cleaning is alot harder than it looks.Lots of posts screw it up, my boat ran before, tried to do perfect maintenance cleaning the carbs now she wont run...
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Disconnect and reconnect exactly,the same
The carb settings will be for example one and a half turns out after gently touching not sure about your carbs.
You should watch all the you tube vids on carb cleaning,don't just watch one and go for it,I learn something watching every video.
For some reason carb cleaning is alot harder than it looks.Lots of posts screw it up, my boat ran before, tried to do perfect maintenance cleaning the carbs now she wont run...

Some carbs do not have a mixture adjustment.
 
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