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1977 JOHNSON 140 tuneup

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gizmolvr

Contributing Member
"i have a 1977 johnson 140. mo

"i have a 1977 johnson 140. motor sat winterized for about 3 years until last year when took it out 3-4 times. Motor ran fine except i do not believe it was charging the batteries when in use. What could be causing this issue? I plan on using the boat a lot this year and would like to give the motor a good tuneup. What parts should i replace? I plan on changing the plugs,wires,lower unit oil.I have the service manual and will be doing the work myself(no good ob mechanics in area). How hard is it to do a carb cleaning/rebuild? thanks for the help"
 
Regardless of what you think &

Regardless of what you think ( good running etc ) you must start with a compression test.Nothing really goes wrong with the carburetors other than gumming up when gas is left in them on extended storage.Change the l/u oil and install a new impeller.Check and retorque the cylinder heads.
 
"the 77-78--140, engine,...has

"the 77-78--140, engine,...has been THE most overhauled eng in my career---31 yrs,..in april...
this admittingly,by the factory,..was due to 2 things,...high ring pistons,..and 'blank'drilled piston pin holes,instead of--'stop' drilled holes.the pins slid in,allowing the rings to spin,catch on ports,..and bingo,.....blown cyl...i bet in 3-4 yrs,..MY shop,..in the early 80's,..overhauled 30-35 140's.....it was a constant,incident.Now,...the big blk,...v6's,..are having the same D### prob.........of,which,..i have one...a 97 200...
when,it blows,..i will fix it right,........unlike,the factory,.....that never,learned thier lesson!"
 
I picked up a 1977 200hp that

I picked up a 1977 200hp that has been sitting for over 2 yrs. The compression is pretty even except for 1 cyl. It supposedly ran fine before sitting up so long. Is it possible that the rings are just stuck..and if so how would be the best way to proceed to determine if there is any physical damage to the piston / cylinder. Can you spray something in the cyl and let it set and accomplish anything..?
 
On the side of the motor you w

On the side of the motor you will see 6 small covers ( 6-- 1/4" bolts) on each one..So you remove that cover and inspect the piston / rings on the bad cylinder.My bet is that will show the problem. There is no such thing as " mechanic in a can " on this one.
 
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