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1973 Johnson 50hp need help please

N

neub77

New member
Hi, I have a 1973 Johnson 5 hp model # 50ESL73R. I've been having trouble with it lately. It will not idle correctly and won't troll down below about 4mph. It ran great up until about a month ago. It would troll at 2.5 and Idle great. Seems like I've lost a few mph on the top end also. I found that the chokes were sticking this weekend and moved the linkage and it came back to life on the idle and low speed for a bit. Now it's back to the way it was. I've changed the plugs and rechecked the chokes and they are not sticking. I have 2 cycle oil dripping down my shaft out of the motor which tells me that it's pushing gas somewhere and the gas is evaporating away. Also it will run great for a mile then bog down and run about half speed for a mile then back to full and so on. My biggest concern is that I checked the compression tonight and the top cylinder is 125 and the bottom is 100. I'm not real sure what they are supposed to be but that seems like a big difference. My next step is to rebuild the carbs then check the points unless my compression issue is the problem. Could someone please help me out and let me know what my next step should be. Thanks a ton in advance.
 
Compression on the bottom cylinder seems low.We were told at service school that only a 12% difference was allowable.
 
Would that cause it to run intermittently? Seems to me like if it were a compression issue it would act up all the time. But I agree those numbers don't seem ideal.
 
Cleaning the carbs won't fix a busted piston ring. Or a blown head gasket. A pedicure won't help a man having a heart attack. He's going to die while you mess around. So will your outboard motor.
 
Round of applause for post #4 and the well chosen words.--------And there are no points on a 1973 model 50 HP.----Remove cylinder head NOW !!! -----Inspect head gasket and cylinder walls.
 
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