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Johnson 84 sailmaster lacks power

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Kincaidelectricllc

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I have a 1984 Johnson sailmaster. I removed the extended shaft to use on my 12 ft aluminum boat. When I use the boat it seems like the motor is running sluggish. It only goes about 8 mph and never gets the boat plained off. It sounds like it needs to rev higher. I have a lot of new parts on this. New coils, powerpack, plugs, rebuilt fuel pump, and the carb was supposedly new when I bought it. Any suggestions. I’m getting frustrated. Starts great and idles great.
 
When running, using an insulated pliers pull one plug wire off at a time. You should get an equal drop in rpm on each cylinder. If no drop, that's the bad cylinder. Ignition, compression, fuel or exhaust.
 
Kincaidelectricllc said:
I have a 1984 Johnson sailmaster. I removed the extended shaft to use on my 12 ft aluminum boat. When I use the boat it seems like the motor is running sluggish. It only goes about 8 mph and never gets the boat plained off. It sounds like it needs to rev higher. I have a lot of new parts on this. New coils, powerpack, plugs, rebuilt fuel pump, and the carb was supposedly new when I bought it. Any suggestions. I’m getting frustrated. Starts great and idles great.
Click to expand...
Did you also change the prop or are you still running the "sailboat" prop.

Did you remove the exhaust plug (#44 in http://www.marineengine.com/parts/evinrude-johnson-parts-diagrams/JOHNSON/44495.gif ) I think you probably did or it would hard ly run at all!
 
vics said:
Did you also change the prop or are you still running the "sailboat" prop.

Did you remove the exhaust plug (#44 in http://www.marineengine.com/parts/evinrude-johnson-parts-diagrams/JOHNSON/44495.gif ) I think you probably did or it would hard ly run at all!
Click to expand...

Vic,

I did not change the propeller. What should it have on it? I use to run a Evinrude 4.5 and I did notice the propeller is smaller. I just figured more hp so the propeller would be bigger. As far as exhaust plug I did not remove it. Unless someone else did. I would have to check. By the breakdown you linked it looked like it was on the extension. Which I have already removed. What was the reasoning for the exhaust plug anyway.
 
The sail versions have a 9¼ x 6½ prop with big "Mickey Mouse" ear blades
The standard prop is 8½ x 9
The lower pitch prop is better for "displacement" hulls like sail boats

The exhaust plug is fitted in the normal exhaust outlet behind the prop of the sail versions to divert the exhaust to outlets in the special extension . It allows the engine to be mounted on a sail boat with the prop deeper than usual without increasing the back pressure on the exhaust. It also prevents exhaust being drawn into the prop when going astern and reducing the thrust.

BTW I have an '84 Yachtwin; the Evinrude version of the Johnson Sailmaster, on a small sailboat
I have some photos which would illustrate my post but am unable to upload them.
 
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Vic,

Where do I access the exhaust plug from? Do I have to split the lower unit? I don't really want to do anymore then I have to, to remove the plug if it's still in there which I assume it is.

Thank you for your help
 
If the plug is there you will see it, or at least the plate #46, and the head of the retaining bolt, if you look up the exhaust outlet. or feel it if you stick your finger up there.

I am pretty sure sure you will need to take the gearcase off to access the nut and and pull the plug out

eurax1.jpg
 
vics said:
If the plug is there you will see it, or at least the plate #46, and the head of the retaining bolt, if you look up the exhaust outlet. or feel it if you stick your finger up there.

I am pretty sure sure you will need to take the gearcase off to access the nut and and pull the plug out

eurax1.jpg
Click to expand...

Vic,

I see what your talking about and yes the plug is still in there. I thought it exhaust up higher above water. I will take it out and let you know what happens. Thank you for all of your help. I was close to just giving up on this thing.
 
You get some exhaust blowing out of the back pressure relief port at the top of the leg. In the sail versions the main outlets are the openings in the extension ( 6hp pictured)

2lmaoev.jpg



33kur82.jpg
 
Vic,

I did remove the exhaust plug. What a difference. Seems like there is plenty of power now and opens right up. I'm going to give it the true test tonight on the open water. I will let you know how it runs.

Thanks
 
Sounds good.. Imagine how your car would perform if you almost completely blocked its exhaust pipe!
 
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