Lets talk H.P. !

[N1265]

Hi Guys,

I just got a 1964 16' Jupiter that came with a 1988 40hp Yamaha. I am sure the Yamaha will fit my needs but I have a chance to do some wheeling and dealing on a 50 or a 85hp Mercury.

The boat is rated for a 80hp mortor and I am wondering just how big of a deal it is putting a 85hp on it ? will it handle the weight ?

Also, just out of curiosity, Is there anybody that can tell me what to expect
( MPH wise ) with this 40hp ? what to expect if I had a 50, 65, 75,or the max rated 80 hp motor ?

Many Thanks,

 

[Bob427]

Re: Lets talk H.P. !

well my 65 jupiter came with a 40hp mariner
its top speed was a whooping 21.5 and let me tell ya what a dog
it was maxed out didn't like it wanted more power

i up graded to 70hp johnson 3 cynlider and now get 35mph out of her
what a difference

you can always go slow but not fast

Bob

 

[tgp***]

Re: Lets talk H.P. !

I'm putting some finishing touches on my 1966 16' Starcraft Nassau w/ 1967 Merc 650 - took it out for its first test run Saturday and it FLIES!!

However, my former boat 1995 Smokercraft Resorter 15.5ft had 25hp, it was the best trolling rig ever, because it could run slow for perfect trolling speeds.

Restore Threadhttp://forums.iboats.com/showthread.php?t=364174

http://s940.photobucket.com/albums/ad241/tgp---/1966%20Starcraft%20Nassau/

 

[Bwana Don]

Re: Lets talk H.P. !

you can always go slow but not fast

Bob

SO true, you ain't got to use them ponies. It's nice to have them though, just in case you need to move it. On my lake a storm can whip up in a hurry. I've seen water spouts on the lake before, we've had to seek refuge in Canadian waters to dodge some storms.

5 horse over should be no big deal, check your local laws though. I hear some states frown on this.

 

[Bob Gilvary]

Re: Lets talk H.P. !

well my 65 jupiter came with a 40hp mariner
its top speed was a whooping 21.5 and let me tell ya what a dog
it was maxed out didn't like it wanted more power

i up graded to 70hp johnson 3 cynlider and now get 35mph out of her
what a difference

you can always go slow but not fast

Bob

This is not meant to doubt what you say, but you're the one that called your boat a dog.

If I can get my 63' Jupiter up to 26 mph with a 25 hp Johnson, that's going by GPS mph, it seems to me that you might have had another issue with your 40 mariner and boat set up. Even the 70 seems slow at only 35 mph.

I tried a 15 pitch SS prop at first, but it was too much for that little engine. Dropped down to a 13 pitch aluminum prop and it made a world of difference.

Hull condition, meaning no concave area near the transom, also known as a hook in the hull, or an under pitched prop, maybe even an over pitched prop, not letting the engine get up to max rpm's, would be two things to look at.

I would think your 70 could easily handle a 19 pitch prop and get you closer to the 50 mph range. What pitch prop are you using now, and do you have a tach on board?

I'd love to have a 40 Yamaha on my little boat. If it's set up and propped right, with no issues in the hull to slow it down, I can see it going 30+ mph and not beat the boat up.

Here's a before and after. Yeah, I got the boat with no windshield and the deck cut out.

 

[ezmobee]

Re: Lets talk H.P. !

In my opinion (having owned one with a V4 85) the ideal motor for a 16' SC is a 3 cylinder JohnnyRude 70/75. Excellent power-to-weight ratio. My V4 was heavy and the boat sat a little low in the stern. One of those newer Yamaha 3 cylinder 90s would be the shiznit also. I wouldn't worry about going over the rating by a few HP. My '66 was rated for 85.

 

[Bob427]

Re: Lets talk H.P. !

my speed comes from my fish finder
no gps yet
neither motor had a tach

my 70 has a 13x17 on it now
i do have a 13x19 i will try next year

that 40 ran like a top just not enough power


Bob

 

[N1265]

Re: Lets talk H.P. !

Well I got the Yamaha fired up today, it took more time to rig up the battery and get a piece of fuel hose than it did to get it started, so I am happy about that.

That being said, I am not sure if it is passing water like it should. I thought they were suppose to spit water out of the hole just under the hood in the back, however all I see coming out is a fine mist, there is a pretty good streem comming out the back of the lower case so I am not sure if Yahama does things diffrently or if the impeller is shot.

I ran the motor for 3-5 minuits at an idle and the head never got hot, but I decided to shut it down and see what you guys think, Here is a couple of pictures.

Also, The number on my prop is 1 1/8 x 13 - G
any idea what the G means ? I assume the 13 is the pitch...

 

[Bob Gilvary]

Re: Lets talk H.P. !

I don't see a water relief telltale on the lower engine cover. Look for it on the lower right side. They clogg up easily on all engine after sitting for a time. That exhaust relief will only mist and spit. Worry if it steams.

Pull the prop, check for fishing line in front of the thrust washer, grease the prop shaft, and replace the prop. Change out the lower unit oil, and I always recommend changing the water pump on a newly aquired used engine.


Bob, I'd be very interested to see how the 19 pitch works on that set up.
I don't have a GPS either, I borrow a friends hand held one though

 

[N1265]

Re: Lets talk H.P. !

I went to y-tube to get a better understanding of the water port and a guy there was clearing his by cramming a piece of wire up there, Is this the correct way or does the thing need taken apart ?


As for replacing the prop, should I be replacing it because you think it might be bad from sitting ?
Or are you suggesting I replace it with a diffrent pitch for more MPH ?

what size prop should I go to for this size boat ?

 

[GLG fishing]

Re: Lets talk H.P. !

I use weed wacker line on my water tell then a shot of compressed air.
Still if it?s a new to you motor a new water pump impeller is good advice.
I think Bob meant replace as in put back on not get a new one.
GLG

 

[Bob Gilvary]

Re: Lets talk H.P. !

GLG, you are correct. Replace as in put the prop back on.

Good advice on cleaning out the telltale also. At the shop, I just use a blast of compressed air, but I've also used thin wire. It all works!

 

[N1265]

Re: Lets talk H.P. !

Thanks for the advice, It is pissing a good stream now...

 

[Bob Gilvary]

Re: Lets talk H.P. !

Something else nice about the Yamaha engines, you can loosen the brass bowl screw in the carbs to drain them for winterizing. It takes a 10 mm wrench.

 

[N1265]

Re: Lets talk H.P. !

Would pulling the gas line and letting it run out of gas be sufficent in draining the bowls for winterizing ?

 

[Bob Gilvary]

Re: Lets talk H.P. !

The bowls never completely drain when running them low on fuel.

I know it was the accepted practice to run the engines out of fuel, but in a mixed gas engine, that would also run the engine lean on lubrication, and it never did completely drain the carbs.

With the VRO fuel pumps in the Johnson/Evinrudes, that caused oil to fill up the carb bowls. It kept the carbs clean, but then to restart later, you had to either drain the carb bowls, or keep priming the engine until the oil was taken into the crankcase with the primed fuel, and eventually get the proper mix in the carbs.

Yamaha made it easy and more efficiant to drain the carbs by how they made the carb bowl plugs. A hole through the center, then another hole crossway through the plug, where all you need do is disconnect the fuel and loosen the plugs. Catch the drained fuel in some paper towels laid underneath the carbs.

 

[N1265]

Re: Lets talk H.P. !

Ok, Thanks for the reply...

 

[MichaelP]

Re: Lets talk H.P. !

1984 16' SS, 2001 40 hp Suzuki 4 stroke with stock prop = 32 mph on fish finder.

 

[N1265]

Re: Lets talk H.P. !

Thanks for the info...

 

[N1265]

Re: Lets talk H.P. !

Fish finder, GPS, "old school" air gage. Witch is more accurate ?

Has anybody been on a boat where all three matched ?