1977 4hp seahorse running pants ! Help please

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keefyc

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Hi all . . bit of advice needed please . i have recently got myself a 1977 jhonson 4hp seahorse (4br77b) and i just cant get it to run nicely :( i have tried everything i can think of ! changed fuel/oil mix to different ratios, stripped and cleaned carb , cleaned and fitted new gaskets to reed valve, cleaned / checked plugs and played with the mixture screw but it still bogs down and splutters on full throttle with lots of smoke ! im no good on 2 strokes and have very little experience with outboards so im begging for any help/advice pls . . . i will give a link to a you tube video of it running when it uploads ! thanks .. keith :confused::confused:
 
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Daviet

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Re: 1977 4hp seahorse running pants ! Help please

A couple of things to do first, compression and spark test.
When you cleaned the carb did you remove the core plug on top of the carb and clean the tiny passages in there?
The static setting on the low speed needle is 1 1/4 turn out from lightly seated, and then fine tune in the water under load.
What plugs are you running, L77J4's?
Most people will recommend 50:1 fuel mixture, but since that engine does not use roller bearings, I mix it 24:1. You will get a little smoke, but the engine will last longer.
 
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hidef

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Re: 1977 4hp seahorse running pants ! Help please

Does it run better if you keep pumping the primer bulb? Your 1977 engine was manufactured with fuel lines and a fuel pump that is not ethanol resistant. Modern fuel will cause those components to breakdown.
 
TN-25

TN-25

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Re: 1977 4hp seahorse running pants ! Help please

1977 marked Johnson's return to all white paint (except for the 1976 Stinger 75 & Javelin 85). It was also the year they switched the small motors to the black box CDI ignition, both a blessing and a curse (mainly a blessing but replacement parts cost more).
 
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keefyc

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Re: 1977 4hp seahorse running pants ! Help please

the original graphics said johnson 4 seahorse ? and it has two spark plugs ? this is a twin !!
 
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hidef

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Re: 1977 4hp seahorse running pants ! Help please

I know it is twin what took me by surprise is the motor cover and tiller handle position. Someone turned that engine into a half breed. The four came with a fiberglass hood and used a remote 3 gallon fuel tank. Graphics could have been changed but that fuel tank is off of a 2 horse.
 
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keefyc

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Re: 1977 4hp seahorse running pants ! Help please

ah so i got a right mongrel then !
 
TN-25

TN-25

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Re: 1977 4hp seahorse running pants ! Help please

keefyc said:
ah so i got a right mongrel then !
Click to expand...
Not necessarily! The European 4 was different than the North American 4 in appearance. Since the 1972 models, the European 4 gained an integral tank like yours, plus the weedless version was not offered. Here in North America the 4 did not receive the integral tank & styling like the U.K. version until the 1979 models. Yours looks legit, except in may be missing the lower cowling. Somewhere I have a picture of a 1973 U.K. 4 in a mid 1970s Avon Inflatable Boat brochure. The graphics were the same 1973 graphics & colours as in the U.S. that year, but it had the integral tank & shroud, the same one that did not make an appearance in North America until 1979 models.
For now I will post 2 pictures; the North American 1977 Johnson 4, and for comparison the 1979 North American 4 with the formerly European-exclusive style integral tank.
 

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hidef

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Re: 1977 4hp seahorse running pants ! Help please

You learn something new everyday. A Belgium 4 horse missing the lower cowling.
 
TN-25

TN-25

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Re: 1977 4hp seahorse running pants ! Help please

Since OMC redesigned the lower unit & gearcase on the 90-degree drive 4 horse for 1973 for North America, they looked a lot like a 2-horse single in the lower unit. Prior to 1973 the straight drive (64 - 72) was actually just a new gearcase & skeg attached to the existing weedless lower unit (for North America). The 1973+ lower unit & gearcase for the high-thrust, straight drive actually was first used on the Belgium 4s from the 1972 models onward.

Here is a link to the Belgian 1975 Johnson version, again courtesy of the Old OMC site: http://www.old-omc.de/j_1975/seite06.jpg. You are right, they sure do look a lot like a 2 horse.
 
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