87 johnson gt200

ranger1850v

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Joined
Jul 29, 2012
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22
87 gt200 looper. I've gotten it to where it'll run okay. Bout 4200 tops unless its cold out. Then I get 4500. Guess that's where the compression is 60 across the board. My problem is is coughs n sputters for a second when I open it up and then it takes off and goes?
 
Joined
Oct 22, 2007
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2,598
Re: 87 johnson gt200

A couple of things. 60 is pretty low for compression, you might want to verify that with another tester. Also, when running properly and with an appropriate prop you ought to be seeing over 5500 rpm at full throttle, maybe more like 5800. IF everything is fine with the engine being overpropped by that much certainly isn't helping the off-idle performance. But the sputtering when it comes off idle could also be a lean condition, or it could be a symptom of something bigger (hence the need to verify compression).
 

boobie

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Nov 5, 2009
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20,826
Re: 87 johnson gt200

Try another compression gauge on it and then verify your spark will jump a 7/16" open air gap on a spark tester.
 

ranger1850v

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Jul 29, 2012
Messages
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Re: 87 johnson gt200

Gauge is good. Comp actually use to b a lil better. I've fought this for a while though. It has a 26p on it. I gained 500revs with a 19p. I've checked the spark n replaced a coil pack. Spark is good. Rebuilt carbs and adjusted per the book. They took the guts out of the airbox to make it like a 225 I guess. Has stock jets.
 

boobie

Supreme Mariner
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Nov 5, 2009
Messages
20,826
Re: 87 johnson gt200

On that mtr the "guts" should be in the air box or else it will run lean. Either get the "guts" back in the air box or try some re-jetting. The way it is now you could burn a cyl.
 

ranger1850v

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Jul 29, 2012
Messages
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Re: 87 johnson gt200

Yeah. Someones tried to modify. Haha. When it stumbles bad I've tried to richen it with the push in key for the choke. It made it worse so that kinda puzzled me
 
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