Which jet

newyota
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Joined: 12 May 2016, 00:55
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Which jet

Post by newyota »

Was looking at a Mercury dealer and a Yamaha dealer today and getting prices and educated on jets and installation.Currently boat I may buy that is a 1993 boat has new Yamaha ( well one year old ) controls and 20 hp Yamaha prop and I need a jet for the river.
Probably trade in the prop with 20 hours on it.Yamaha dealer said they had a used two stroke 40 jet that must have been traded in and they still had to work on it and get it ready to sell.Sure it will be much less than a new $7500 60/40.Said the two stroke would have more power if I went that route and I could use the new controls.They told me a Yamaha jet would be a direct mount like the 20 hp for that size jet,any bigger it would have the transom extension put on.Looking at a Mercury 60/40 and that would require new controls at another $400 I think.That dealer said the Yamaha was not a direct fit and needed the transom extension ?I know nothing about maintIning a jet and never drove a boat with one,but see them all the time on river.Any words of wisdom appreciated.

CedarRiverScooter
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Joined: 13 Nov 2014, 08:01
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Which jet

Post by CedarRiverScooter »

2 cycle jet will use lots of gas, so buyer beware on that.

On the plus side it will be much lighter than a 4 cycle.

As long a the motor is in good shape you can always resell if you don't like it.

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JL8Jeff
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Location: Ewing, NJ

Which jet

Post by JL8Jeff »

The shaft length on the motor and the transom height will determine the mounting position and whether it needs a transom extension or riser. The front foot of the jet needs to sit almost level with the bottom of the boat. A short shaft motor is 15" in length, the long shaft is 20" I believe and the newer long shafts might be 25". So if you get the wrong shaft length, the motor might need to sit 5" higher on the transom. What is the transom height on the specific boat you are looking at?

Here is a picture of the Mercury short shaft jet (15") on my Lowe which is a tunnel jet hull. You can see that the motor is mounted almost 2-1/2" above the transom to get the foot just under the top of the tunnel. I think I tried 3 or 4 mounting positions before I found the optimum spot (least amount of spray back and best performance without aerating the jet).
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2001 Lowe Roughneck 1652 VT with Merc 60/45 jet 2 stroke

newyota
Posts: 97
Joined: 12 May 2016, 00:55
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Which jet

Post by newyota »

thanks for the info guys.

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idruthrbfishin
Posts: 67
Joined: 20 Nov 2018, 12:17
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Which jet

Post by idruthrbfishin »

newyota wrote: 31 Jul 2021, 13:29 thanks for the info guys.
Go for the 60/40 2 stroke Merc you won't be sorry. I switched from a 25/18 tiller to a 60/40 remote in 2017 wish I would have done it 10 years ago.
HVAC mechanic in NEPA for 25+ yrs.
1998 Crestliner w/ 2001 2 stroke 60/40 Merc Jet
1986 16' Grumman Skidaddle w/ 60 HP Evinrude
1955 14' Viohull
1958? 12' LoneStar

turbotodd
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Which jet

Post by turbotodd »

typically if you have a 20" transom, you will use a short shaft motor with a jet foot. After installing you will have to adjust the height. Jets are critically dependent on motor height. If you have a 15 (short) transom, you're gonna have to extend the transom for a jet. There's more to it but that's the nuts and bolts of it.

Maintenance. Check and adjust the impeller to housing clearance once in a while. How often? How often do you suck rocks and sand into the foot? Impeller will need to be changed once in a while too as rocks and sand tend to wear the tips. The housing (aka sleeve) also wears out so it may need to be replaced every so often. Grease the fitting as well.

The best day of owning a jet is the day you buy it, performance drops off from that day on as the impeller and sleeve wear. We rented a Topwater 20' a couple years back, 40/30 Yamaha. It did what it was supposed to do but it was no fun. Noisy, don't turn very well, used a lot of fuel, and ran on the limiter most of the time. But it would run shallow and sucking up rocks wasn't an issue. Wasn't my boat why did I care what it sucked up. We run up into a creek that was a muddy bottom, and ended up sucking up a bunch of leaves and junk into the intake, had to shut it off and clean the grate so it would pull itself again. Went back into the river (gravel bottom) the rest of the day and frankly a prop would have gone everywhere we went.

Now if you've never been around jets, get the 4 stroke. End of story. Why? A jet is going to use more fuel than a prop that is just how they are. You basically run near full throttle all the time and you need throttle to "turn". They don't turn very well regardless. You'll need a big fuel tank depending on how far you plan on running. If you end up with that 2 stroke? OMG, buy the best ear muffs you can get because a 2 stroke jet is noisy. 4 stroke jet is a little on the loud side too but NOTHING like a 2 stroke jet. I won't own one and neither will a lot of others. I run my prop motor and enjoy not having to use ear protection, and enjoy the lighter weight (don't have to carry 10 gal of fuel)--the only downside is that it won't run in less than about 8" of water. Big deal. Every Saturday on the river there are a pair of two stroke jets; one is a 20' shawnee with a 30hp (4 cyl) Mercury jet; the other a 80hp Mercury jet. No kidding you can hear them for at least a mile away. When one of them starts the engine at his boat house and heads upriver, I know it--and I'm really close to 1.1 mi away. I feel sorry for those that live and camp on the river's banks whenever those two guys are running.

Pawatch
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Joined: 22 Jan 2020, 17:26
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Which jet

Post by Pawatch »

Some people prefer Mercury, others prefer Yamaha. Think the most important thing is having a good dealer.
I own 2 jets...25 Evinrude and a Mercury 115/80 4 stroke.
Basically the only maintenance is just grease the jet pump about every other time out. Just a small grease gun and give it 2-3 pumps.
2 stroke jets tend to like fuel. Where my 4 stroke not as much.
Learn the water your running. Jets aren't totally invincible. But they get you to water that a lot of people can't get to.
Enjoy!!