'71 125 questions

[jklett]

Hi, I have a 1971 125hp Evinrude model# 125183C that I am attempting to fix. All I have done so far was to remove the heads and take a look. It looks like I blew a ring, as there are chunks out of one of the pistons, and also out of the head. I also found a piece of the ring stuck in the head. The cylinder bores have slight scoring, but I've honed out worse in car engines. I've turned the crank to check the rods, and all four seem OK(move with crank at middle of stroke). My questions are 1, besides pistons, rings, and gaskets, what else should I replace while I'm in there? Question 2, will the heads from a 1961 75hp fit? Anything else that can guide me along would be great, as this is my first experience with outboards. By the way, I do have the sevice and parts manuals, if that helps.

 

[OBJ]

Re: '71 125 questions

Hi Jason....sorry about your troubles. It does happen.<br /><br />You'll want to mike the cylinders for sure. By the time you get the honing done to remove the scores, you could be at the limits of the standard bore which are about .004 over standard bore. <br /><br />When you get her tore down and on the bench, check all the bearings are still servicable and the crank races are not scored.<br /><br />Don't know if the heads will interchange. A guess would be no.<br /><br />Rebuild the carbs. Don't leave this step out.<br /><br />And see if ya' can determine the cause of the problem to begin with. Sounds like heavy carbon to me.<br /><br />Make a list of parts you need as you go along. This will keep ya' from forgetting anything needed.<br /><br />Hope we've helped a little. Keep us posted to your progress. And if ya' don't have a service manual.....get one.

 

[ledgefinder]

Re: '71 125 questions

There are a number of alternatives to rebuilding that 125 powerhead. <br /><br />I mention that because the pistons are a little odd on that motor (1971-72 125hp) & I'm not sure they're still available. I don't think they're the same as the 3.5" ones they used on tons of motors just after that. <br /><br />Any 1969-72 V4 powerhead (125,115,100 & 85) will bolt in. There isn't all that much difference in real power between this set of V4s - just some tuning differences & marketing. The 85hp is 94 cubic inches, and the 125 is 100 cubic inches. I've seen good 85hp powerheads list on eBay for under $100, and not sell. <br /><br />Alternately, the parts off your motor, particularly the hydroelectric lower unit, and the ignition, are worth around $250, so might consider parting it out & putting the money into a newer motor. <br /><br />If you're not going to part it out, I'd find a good used powerhead & put that on. The 125/115s do have some added top-end over the 85s(but less midrange), you can bolt on the 125 carbs if you're after top speed. Your ignition system will work with the 85hp crank (crank has both cam & holes).<br /><br />Sounds like you already know you ought to replace the head. Those divots may cause hot spots & pre-igntion.

 

[jklett]

Re: '71 125 questions

Thanks for the replies. According to the manual, it seems that the '73-'75 115, the '71-'72 125, and the 135(not sure on year as the book I have only shows '65-'75 motors)all have the same 3.5" bore and 2-19/32" stroke with a 99.6 cubic inch piston displacement. Could I use pistons and heads meant for these motors? What about other parts? It seems to be easier to find stuff for a '73-'75 115. I will try and find a used powerhead, but I may run into a similar problem with whatever I find, due to the age. That's part of the reason for my wanting to rebuild this one. Plus, I could use the experience.

 

[phatmanmike]

Re: '71 125 questions

jason, not to sound negative and all...but i have similar motors, 55 and 85 hp, both 1970 and 72 respectivly. i just parted out my 85 hp sold lower unit for 51 dollars and ignition is currently on ebay, as are many other parts. the age on that beast is a big negative. i suggest part out as much as you can, and i mean sell everything, even the bolts, if you list them , they will sell.<br />then maybe get something a lil newer than 34 years old and out of the electric shift era. i say this from experience as i hav and had these motors. i have the power head from my 85hp sitting in my truck right now... over heated and would never restart, but still spins freely.<br />just my 2 cents