1974 Evinrude 25HP goes slow but not fast.

Hello everyone,
I just had my 1974 25HP Evinrude repaired by a local shop here in NC and I'm still having problems with it. Before I take it back, I was wondering what I can tell him to look for when he gets back to it.

Here's the problem. The person I bought the boat and motor from didn't take care of it. The person before him didn't either. I doubt if anything really ever was done to it. So he did a total overhaul; replaced points, lubed stuff, repiared stuff, etc.

But the main reason I brought it in to him was the problem I still have, which is after going across the lake for about 2 minutes, I lose the ability to go fast. I can go slow (putting back to the dock ) but whenever I try to go faster than slow-idle speed, the RPMs pick up and I stop moving forward. Once I get back to a slower RPM, it kicks in and I start to move forward again.

The only thing I've heard of so far is an ignition coil, which after it warms up opens up and quits working. I don't know what to look for (I have looked for a part that looks old and possibly bad).

Any ideas?

Re: 1974 Evinrude 25HP goes slow but not fast.

The clue is obvious: Your propeller hub is "spun", that is to say it is slipping. It is like spinning your wheels on an icy road. Motor revs up, car doesn't go.

The fix is obvious also, replace the propeller. They can be re-hubbed, if you think the overall condition of it warrants.

All this is incorrect if your motor is actually jumping out of gear, into neutral, and / or making a grinding sound.

Re: 1974 Evinrude 25HP goes slow but not fast.

Oh, this makes me so happy. Well at least I'll have something to look into. I'll let you know what I find.

And no, it doesn't go into neutral nor does it make any noise at all. I do remember the guy that sold it to me gave me a spare prop. I found it odd but maybe it has something to do with my problem!!!

Thank you very much for responding.

Re: 1974 Evinrude 25HP goes slow but not fast.

Well I finally got to it but everything looks good. There is a shear pin holding on the hub. Then the hub unscrews and I can slide the prop off. There is a slot on the inside of the prop where a thicker steel pin fits into. Everything looks like it fits together correctly.

Is there anything I should look for? What would make the prop look bad?

Sorry for my ignorance; just hoping for some answers. Plus I am hoping with this being the weekend I might get more people to look at this. And thanks to my job (and the economy) I have off on Monday (I build school buses) so I have time to tinker.

Thanks again for any info.

Re: 1974 Evinrude 25HP goes slow but not fast.

it could still be a spun prop. the prop is made of an inner metal hub, and an outer metal hub with the fins. in between is a pressed in rubber bushing, these are known over time, to loose their gripe. thus the inner hub spins, and the outer does not, when you slow down then the rubber can gripe again. this is a newer and bigger prop, but you can see the basic make up. draw a line across the prop, and give it a spin around the lake, bet the line is not inline.

Re: 1974 Evinrude 25HP goes slow but not fast.

Well I took off the prop (finally) and I looked at it but I'm confused. All I see when I look at the inside is metal. I don't see a rubber ring at all.

Is that bad?

I'll work on getting a picture for this soon.

Re: 1974 Evinrude 25HP goes slow but not fast.

don't worry Brian,
It doesn't LOOK like it, but there IS a rubber hub in it. From your description, that is almost surely what it has to be. Just mark it like Tashasdaddy said and find out for sure.
Later,
JBJ