Ever replaced a power head?

[Guest]

1979 Johnson 115, fuel problems. Long story short, has a scored cylinder.

Wondering if anyone has done a powerhead replacement, is it risky or can I bolt it on and go?

[kjgmh]

Powerhead replacement is pretty easy on that motor. I would take plenty of pictures before swapping so you know were everything goes. Make sure that problem that caused scored cylinder is fixed.

Good Luck

[Guest]

Thanks,

There is some major contamination in the main fuel tank. I hired a guy to look at it when it started running poorly. He said the carbs were full of bugs and chunks of rubber.

I switched to a remote tank but must have been to late.

How long do you think it would take? We tried for a day or two to get it to run right by changing tanks, plugs, etc, plus it ran ok for the first season I had it, but it could have been running to rich or lean at that point.

Also, the previous owner stated that he had a piston replaced. Could have been they did not do it correctly, or did not fix the real problem.

Also found the low speed jets were installed wrong. .027 should be on starboard side, .028 should be on port side. Whoever had them out last put the .027's in the top carb and the .028's in the bottom carb.

Do you think the jets alone could have caused the failure?

Top edge of piston is gone over exhaust port, lower cylinder starboard side.

Appreciate any info anyone can post.

Thanks.

[panolo]

Jiffy,

It is not that tough of a job. Even though I haven't done it for a few years the one thing that I made sure I had was the repair manual. Don't know that I used it that much but it was comforting to have. ALso the pic idea is great. When we did ours it was probably 10 years ago and the digital cameras were a little too expensive for us then. Your jet issue probably didn't kill it by itself. It didn't help though.

[musky hunter]

I've replaced and/or rebuilt a couple. It's not what I really want to spend my time on. If you feel the motor really is worth the effort, you have a couple of options. One is to rebuild the power head. That boring or honing the cylinders and then fitting proper size pistons, (readily available), various bearings and gaskets, having the cylinders bored or honed, and a whole bunch of dissasembly and reassembly. but you'll have a great power head. If you have a used powerhead, it's only a matter of swapping things out. Rebuilding a 115 would cost about $500 to $1000 in parts alone, and you might double that if you have to pay to have it done. Swapping is just the cost of the new powerhead plus the labor to do it. My advice, on a 1979 motor, unless you have the time and the skills, you might be better served just buying a whole new replacement motor and selling the lower unit off, you might get $250 for it.

[Guest]

The lower unit seems pretty sound, no leaks or funky noises or shifting problems.

Im leaning towards buying a rebuilt powerhead. Kinda spendy and Id rather be fishing but at least Ill know what Ive got when Im done.

Thanks for the info.