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1978 Johnson 85 two stoke, won’t go more than 10-15mph

J

Jrwelck

New member
From the beginning, this boat sat for about 3 years. So tried reviving it. At first I had no knowledge of boats at all. I could always get it stayed but come to find out the choke wasn’t closing all the way. I didn’t find that out for about a year into it. It would be very hard to start but once it did, for the rest of the day it would start on first crank for the rest of the day. So i started trouble shooting. So far I’ve replaced, bad power pack, 4 spark plugs, all new fuel lines, new primer bulb, new battery cables, choke solenoid, starter, and more. Now, the boat is at the point where it fires up beautifully. But will not go past 15 mph. I’m sure it’s not good but I tried something yesterday, I choked the boat for about two seconds while running full throttle, and it picked up and went full speed. So I ran it for a couple minutes like that, then fished for a couple hours. Tried the same thing on the way home but it only worked for about 10 seconds then bogged back down on its own.

Compression test was
110
110
100
100

im not sure what jumping 7/16 gap means but I bought a spark tester and they all have spark.

So long story short, used to be hard to start but once it did it ran flawlessly. Now I’ve replaced a bunch of parts and it starts perfect but won’t get up to speed.
 
Could very well be a jet restriction in your carbs. Do you use ethanol fuel? Was it stored with fuel residue in it? If that residue had ethanol, then you can assume that it needs carb work. Since it picks up with the choke, then we can predict that there is adequate fuel delivery at least to the carbs. You can also try Amsoil "Quik Shot", which will physically remove light coatings of fuel created residues within the fuel system, including the main jets. Follow directions from Amsoil found on line, or on the bottle.
 
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It was stored with fuel in it, I’m not sure if it was ethanol or not. I don’t know much about the carbs but I did take them out and disassemble them. I wasn’t sure what I was looking for or how they were even supposed to look, but there was no residue of any kind on them. I have been reading about People having problems with high-speed jet’s, but I can’t seem to figure out what they even look like
 
You'll find some plugs in the bottom of the carbs. The high speed jets are behind them and it takes a special screw driver to remove them.
 
???-----The bypass cover is on the side of the block.----6 wee bolts.----And a $2.00 gasket as stated.-----Lets you do an inspection.------Clearly you misunderstood post # 7
 
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