Which motor would you choose?

[swire]

I'm looking at changing the motor on my 15ft run about from a 1965 Evinrude 75hp, which barely if ever was able to get my boat on plane. Right now I've come across two different motors locally for sale by a guy who does nothing but fix motors. The first is a 1978 Johnson 75hp 3 cylinder with no trim for $800. The second is a 1977 Johnson Javlin 4 cylinder with power tilt and trim for $1,200. He has to put a lower unit on each of the motors which is included in the price along with the controls. He also said he would go over each engine to clean it up and make sure it was running good again.<br /><br />The prices seem reasonable, so given the two which would you choose and why?

 

[pine island fred]

Re: Which motor would you choose?

Just curious, can you read the data plate on the boat? What is the max h.p. rating? 75 h.p. sound like a lot of engine on a 15 ft. boat. regards fred

 

[Scaaty]

Re: Which motor would you choose?

Simple. If you use the boat mostly by yourself, go with the 3 cylinder...raced the 3 cylinders in the 80's.<br />Ski, or more people, get the workhorse 4 cylinder

 

[swire]

Re: Which motor would you choose?

Originally posted by pine island fred:<br /> Just curious, can you read the data plate on the boat? What is the max h.p. rating? 75 h.p. sound like a lot of engine on a 15 ft. boat. regards fred

The plate said my boat can take up to an 85hp motor.

 

[swire]

Re: Which motor would you choose?

Originally posted by Robby6950:<br /> Simple. If you use the boat mostly by yourself, go with the 3 cylinder...raced the 3 cylinders in the 80's.<br />Ski, or more people, get the workhorse 4 cylinder

The boat will be used mainly with at least one other person and a bunch of fishing equipment plus trolling motor and extra battery. So it sounds like 4 cylinder is the way to go. Is $1,200 a decent price for such an old motor? He had wanted $1,500 but I talked him down.<br /><br />Also will the 4 cylinder be enough to pull a skier? This is my first boat and I'm severely disappointed in the lack of power the current 75hp motor has.

 

[rabidfish]

Re: Which motor would you choose?

How does your boat sit in the water with an extra 100lbs hanging off the transom?<br /><br />Just want you to think about it...

 

[swire]

Re: Which motor would you choose?

Originally posted by Rabidfish:<br /> How does your boat sit in the water with an extra 100lbs hanging off the transom?<br /><br />Just want you to think about it...

Well it currently has an older heavier v4 hanging off it. From what I can tell the boat sits fine with it. But I was wondering how much of a trade off is there of going with 100lb lighter 3 cylinder vs the the heavier more powerful 4 cylinder. If it's close to an equal trade then I would be better off with the 3 cylinder as it's a lot cheaper. But if the 4 cylinder would still perform better despite the additional weight then I would be better off with it. Any input?

 

[ledgefinder]

Re: Which motor would you choose?

The 75 should be plenty to ski with. <br /><br />The 75 is 50 cubic inches, and the 85 is 94 cubic inches; nearly double the displacement. Everywhere but on the wound-out top end, the 85 will feel like twice the motor - and it'll use gas like twice the motor.

 

[pine island fred]

Re: Which motor would you choose?

Still a bit perplexed on how a 75 cant push a 15 ft. runabout, motor must be real tired. I know its a dumb question but are you sure it is a real 75 hanging on the transom ? fred

 

[piniongear]

Re: Which motor would you choose?

I would ask your man about the engine history (if he knows) because there was a piston issue on the V4's during this year model time, and for a few years beyond.<br /> The pistons had a design error putting the upper ring groove too close to the piston top. The pistons will burn thru after some time. OMC redesigned the piston after this was discovered (read that engine failures). I had a 78 V4 that the dealer would not take on a trade in 1992 because I had the original pistons still in the engine. Discouraged, I kept the motor and one year later I got a burn thru. I guess I remember so well because it was a sixteen-hundred dollar fix. So, be aware if you chose the V4.

 

[JRJ]

Re: Which motor would you choose?

I sold a 1990 Johnson 120 that ran for $1,000. I think those motors are over priced. Or maybe I just gave someone a good deal

 

[swire]

Re: Which motor would you choose?

Originally posted by pine island fred:<br /> Still a bit perplexed on how a 75 cant push a 15 ft. runabout, motor must be real tired. I know its a dumb question but are you sure it is a real 75 hanging on the transom ? fred

Yeah it's a real 75. I also did a compression check on it which came back a little low, 94lbs in all the cylinders but it was equal all the way across. With just me in the boat it would 2 minutes to get on plane if it ever made it. With someone else in the boat...forget about it. The prop on the boat is only a 10 x 11 which is standard for that motor.

 

[jafa]

Re: Which motor would you choose?

Compression is not bad, that might come up a few points after a decarb, whats the rpms at WOT.

 

[imstillatwork]

Re: Which motor would you choose?

just for reference, my 1981 70HP was 125psi on all 3

 

[jimmbo]

Re: Which motor would you choose?

Swire. you might want to try the 10 x 9 1/4 prop that is offered for your motor. Other than that, go for the V4. The 3 cyl 75hp was designed for top speeds on very lightly loaded boats, the 70hp from which it was derived was a much better all around motor. Especially when it comes to low end torque.

 

[McGR]

Re: Which motor would you choose?

I find it hard to believe the older 75hp had problems getting on plane. Sounds like something is wrong with the old 75. In good running condition the old 75 V4 should have plenty of torque for your rig... unless the boat is made of concrete. <br /><br />If you've already written the old motor off... I'd go for the 85hp. If you've been having problems getting out of the hole, the 85 would certainly be the better choice.

 

[Basscat 1]

Re: Which motor would you choose?

Go with the 4 cylinder with power tilt and trim, hands down.

 

[reeldutch]

Re: Which motor would you choose?

1200 for a 1977 v4 85hp sounds like a lot to me.<br /><br />ask him wat he will do on the engine.<br />and if there are any new parts on the moter and if he will give some kind of warantee.<br /><br />i would not pay more than 750 for a good running 1977 johnson/evi 85 horse unles it is completely rebuild with some warrantee.<br /><br />good luck reeldutch

 

[Scaaty]

Re: Which motor would you choose?

Originally posted by pine island fred:<br /> Still a bit perplexed on how a 75 cant push a 15 ft. runabout, motor must be real tired.fred

Its a 1965...read his post. Even when new, they barely pushed old wood boats at 20 knots with that tiny prop. Swire, pull it and sell the parts on ebay. $1200 (did anyone read his post? ..motor/controls/looked over lower and gone over upper, and sounds like installed... A BARGAIN at $1200) for the 85 will make you a happy boater. We have one in our marina, probably exactly like what you propose, always has 2 people in it, and they are always smiling. Screw theory, go with reality! Good luck!

 

[ledgefinder]

Re: Which motor would you choose?

We skiied behind a 1960 40hp, on a 16foot PennYan (wood), for years. Anybody wanting to pay $1200 for that motor, please let me know.