rebuild question

[scott68]

i am looking to rebuild my 1984 Johnson 70. Nothing wrong, runs good but it's losing a little bit of it's kick and comp is low but even,95 - 100 across all 3. I'm sure it's never been done and instead of getting another motor which i don't know the history of, this sounds like a good idea to me, and it's good on gas so going bigger would take that away. What can I expect to pay for a rebuild, as nothing is broken so it would be parts and labor. thanks

 

[tashasdaddy]

Re: rebuild question

i would do a decarb before a rebuild, that is a lot of money for a running motor. depending on you tester, the compression is passable. you might try another tester, as the do read differently.

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

afterwards compression.recheck

 

[scott68]

Re: rebuild question

i am sure i did slight damage a couple of seasons ago tho. i ran without oil for a bit and the engine quit on me. didn't know what happened at first then realized what i did, put oil in after it cooled down and away i went for a day and then warped the head. i fixed it and was ok but i'm sure it hurt something inside. i will do the decarb today, i've been reading all the suggestions to others about this but haven't ever tried it. out of curiosity how much would the rebuild run?

 

[SKEETR]

Re: rebuild question

It depends how deep you want to go with it. Bearings get spendy but if she runs fine now they may not need to be changed. If the pistons are good as well you may just need rings and a cylinder rehone. You want to call around for prices from a local machinist. Don't take the lowest price unless you feel absolutely comfortable with them. Better to use a higher end shop tooled for small engines. Check your model/year for parts on the j/e site. Do the work yourself and probably get it all done for 3-400 bucks including the oem manual. Not including the cost of beer though...

Overheat could mean needing new pistons possibly oversize depending on condition of cylinder scoring. Follow tdaddy's suggestions. I agree that your readings didn't look too bad. Just thought you wanted to throw some money at her.