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PostPosted: 25 May 2011, 19:01 

Joined: 18 Jun 2010, 20:26
Posts: 41
Location: Northern Arizona
Hey Gang,

Just got a 1974 Johnson Seahorse 6hp..... Model: 6R-74C SN: J39444424

The previous owner said it ran good and last used it in November 2010, it has sat for 5 mos, and now it won't start....he said he did nothing to try to fix it....

I am guessing to start w/clean plugs, maybe clean carb....

Any other thoughts?

Also, the points/condenser on the motor look automotive....is there a PN I can pick them up at the auto parts store....?

THX for any tips, ideas and thoughts!

Garrett


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PostPosted: 25 May 2011, 20:05 

Joined: 08 Nov 2010, 22:53
Posts: 54
I'd advise to do the typical diagnostics:

1. Check for spark. Should be able to jump 1/4 inch with a nice hot blue spark on each cylinder.
2. If there is spark, check fuel delivery. Get a spray bottle with a mix of gas/oil and spray into carb. If it starts momentarily and stops, then you probably need to rebuild the carb.
3. Check compression. Should be near equal on each cylinder.

if you need parts, I'd go to iboats.com, to their store.



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PostPosted: 26 May 2011, 21:15 

Joined: 15 Mar 2011, 10:58
Posts: 40
If you have NAPA near you try there for points and condesers..


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PostPosted: 28 May 2011, 15:38 

Joined: 24 Mar 2010, 00:02
Posts: 381
Here are couple links that may help you out.


Very good read on general maintenance and general repairs on your motor with pictures.

http://www.sschapterpsa.com/ramblings/OMC_6hp.htm


Website to get factory or Sierra made products...coil, points, condensers, carb kit...etc etc It will also serve as good parts diagram.


http://www.marineengine.com/parts/johns ... odel=6R74C


Before you start spending a lot of money. Please do a couple of things.


Here is some guidance that will help you evaluate your motor and help us help you!

Now you want to use a systematic approach to assess your engine's problem. Sure, it maybe just needing a carb kit and cleaning and your on your way. But if you a systematic approach to evaluating a motor then you become more efficient than you just guessing and changing out parts.

You will see a lot of experience guys ask about compression, spark and fuel. (They are using a systematic approach to diagnosing an engine problem or problems....in this order)

C= compression ( if your compression is low or uneven between cylinders >10% then others checks don't matter until the that is resolved) Low compression will cause your motor not run or run very poorly.

S= Spark (if your have problems with your ignition then you can have the cleanest carb and great fuel delivery but it will run bad or not at all)

F= Fuel (if your carbs are not clean and fast/slow idle needle are not set right then it will run very poorly. If you have it set too lean then you run the risk of poor fuel/oil delivery and damage your pistons and cylinders then you run into the problem of C (poor compression from damage).

For your motor to run and run well (this a general statement) all three of above categories need to be fulfilled.


How to check compression: (remember to remove both spark plugs and ground both wires so the coils are not damaged) You can get a compression guage for about $10 to 12 dollar at harbor freight or auto zone) auto zone will let you borrow one with a refundable deposit)

http://www.youtube.com/watch?v=PyCw4SiuT2I (gives you visual)

How to check for spark.(with a spark checker) about $6 at autozone (or similar store)...harbor freight store. You will also need a feeler guage to gap your spark plugs to 0.030 (feeler gauge is about $3 to 4 dollars)

- adjust the spark test to about 5/16 inches or so. It should be a good strong blue spark. (don't forget to ground the tester to the motor) When someone just grounds the spark plug to the motor and see if there is a spark and call it good....that not enough. You want to access the quality of the spark. The quality of the spark tells you the health of the ignition system. A spark that can not make a jump of 1/4 to 5/16 on the spark tester is indicating problems.
-could be pitted or fouled points
-could be a cracked coil that is still somewhat functional but not dependable.
-etc

http://www.youtube.com/watch?v=lk70oyUEftY (general visual)

Carburetor adjustments

Quote:
Carb Needle Adjustments For Asorted Carb Variations by Joe Reeves

these adjustment are for the older engine. 1980 and earlier, and the current small hp ob's. not for fixed jet outboards.


(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.


When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.



This will at least get you started and give some information to experienced guys on the forum and they can give you good guidance and get your motor on the water!!


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