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Thread: Putting a Jet unit on an Outboard.

  1. #1
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    Default Putting a Jet unit on an Outboard.

    What should a person look for if they want to purchase an outboard and have the dealer install a jet on it?
    Does the dealer normally keep the lower unit or give it back? Can you install the basic jet package on any of the larger 4 strokes that are rated 150-200 for prop use?
    Are there good brands versus one's to avoid?
    Tennessee

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    Default depends

    It all depends on what you buy. If you buy a motor with a prop, AND a jet then you will get both. If you buy a motor and say you want the jet, you will only get the jet. An example is my 25 merc. I bought the motor. I also ordered a jet for it. So I have both, it takes me about 45 minutes to change it out.

  3. #3

    Default Jet pump

    I've got a 25 hp Evinrude. What would a jet kit for it run, any idea?

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    Default Depends and then some

    I was looking to do this with my rig since I have a decent diversity of prop and jet waters in my area but also long distances making the prop attractive.

    That said, changing them out is not incredibly difficult and depending on the model it can be done on the fly at the mouth of a river...but, the larger the motor (90 plus), it's a big jet or lower unit housing and it would definitely be a hassle without being on dry land with strong buddies and mechanical aptitude.

    So, Fisherman222 has it right as far as dealing with a dealer, there are lots of options but it usually requires buying one or the other....and getting the accomanying lower unit. When I was looking at mine, I bought a four stroke jet...and intended to get either a rebuilt or used lower unit later on. (new for a 60 Yammer 4-stroke is around $1000..prop) But, the other issue is mounting height, you will need to raise the height of a prop powerhead between 5 and 6 inches off the transom to go from prop to jet....most commercially available jackplates do not do this (but many are very close, within an inch, so it would often mean getting a welded jackplate and taking that on and off to change out, or finding/building a plate with that kind of travel. The bigger you go, the bigger of a pain it can be.

    For mine, a jet unit was around 1600 if I went with the prop to start with. So I had to ask myself (since I'm not made of the blingy blingy) which one would offer me more access....so I went with the jet and burn a bit more fuel (but not bad) than I would with a prop, but my access is only limited by my skills. And also I had to decide if it was worth the pain to try and find a jackplate that would ease the transition from prop to jet.

    As far as jet units go, I've driven 150 Yammer and Honda outboards with jet units but the Yamaha seems to be the better performer (more the motor than the jet on the difference)

    Knowing the diversity of rigs and the gumption of boaters in AK I'm sure someone has done this and look forward to hearing what they found. I ended up just opting for the jet due to monetary restrictions and so far am quite pleased.

    Unless someone can show a clearer and easier way to do this jet/prop combo, I'd suggest go with a four stroke jet...and as big of one as you can stand transom and costwise...there is nothing worse than an underpowered jetboat....if you try to save a grand or two by opting for a 115 over a 150 powerhead you will sob each time you look at your bank account and think of your doggy performance.

  5. #5
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    Default

    Are all jet units bascially the same except for there size? Are there brands to avoid? Should you get a ss impeller over the standard steel?
    I am considering purchasing a Woodridge Alaskan 20 late this summer (trying for a price break) and will add the motor next year. My initial thoughts are either a 150 Yamaha or Honda or a 175 Suzuki (all 4 strokes). The gear head in me will never die and if the price is right I would go for a 200.
    It certaintly would be nice to have the ability to convert the motor from jet to prop to save fuel but I wonder if it is worth the expense? I would assume you need an extra long shaft motor and then an expensive jack plate.
    The only time I would see the need to have a prop is if I am running up to the Yukon or beyond to do a moose hunt. We already have an ocean boat so it would never see salt water.
    I appreciate everyones opinion on this subject.
    Tennessee

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    Default brav1

    I paid for my motor with a prop and then a jet seperate it was slightly cheaper that way. my jet was 1300 I think. maybe a touch more.

    I didnot have a choice, I had to go with "outboard jets" brand.

  7. #7

    Default Only One Manufacturer

    Specialty Manufacturing out of San Leandro, CA. I reccomend ordering your outboard with a jet. The dealers order both (outboard & jet) and remove the lower units and install the jets. They then sell the lower units for a much reduced price. I bought one for my Honda 90 for $750 vs $1,100 (with a prop).

    Swapping around is kind of a pain if you don't have an adjustable transom jack. Otherwise, you need an engine hoist (for 50hp and up) & you'll be plugging bolt holes in your transom. The shift cable may need to be swapped because of the difference in length requirements between a prop & a jet.

    I'm sure there are other (and probably better) opinions, this one is mine.

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    Default specialty manufacturing

    THat is the same place I got mine, but it also had a name "outboard Jets". hmm

    With my smaller motor the prop lower unit is more expensive than the jet when I priced it out at Marita two years ago.

  9. #9

    Default Prop-to-Jet

    I bought a 200 Honda for a Wooldridge Sport Drifter. Essentially all outboard jets are built by the same company. Specialty Mfg. Co. in San Leandro, CA is their name. (Tel. (510)562-6409 www.outboardjets.com ) When I bought my boat, I wanted and ordered the Yamaha 200. Glenn Wooldridge called me back and suggested I go with the Honda if I wanted to swap between the jet and the lower unit frequently (I usually swap back and forth about 3 times per season). The Honda XXL shaft is an XL shaft with a 5" spacer in the lower unit. This spacer allows you to mount the motor at the correct height for the jet unit. When the lower unit is installed, the spacer is installed first, then the lower unit. This leaves the lower unit about 1 1/2" higher than optimal but still acceptable. The bass boats and fast lake boats run the motors as high as they can without cavitating which is more than 1 1/2".

    By using this Honda set up, I can switch back and forth without having to relocate the motor. I'd stay away from a jack plate if you can. The jack plates move the motor further back from the transom (some as much as 6") and allow for the introduction of air. If you opt to go with the Yamaha, you can go with the XL shaft and buy an extension kit from Bay Manufacturing (www.baymfg.com) and achieve the same thing I described above. When I bought mine though, it was substantially more expensive to go this route.

    If you buy the motor with the lower unit, then have them install the jet unit, you should keep the lower unit unless they give you credit as a trade in or something like that.

    I've found it worth while to swap between the two. I run the prop for the majority of the summer for the fuel savings and speed (I frequently make long runs) as well as in the salt water, then I run the jet in the late fall for the low water reasons.

    Hope this helps. Ask if you need anything more.

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    Default eggy

    I have the same 5 inch shaft extension peice for my 25 from bay manufacturing.

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    Default

    Eggy,
    Great advice. Thank you.
    Just so I have this clear in my mind, you went with an XXL shaft on a Honda outboard and mounted the motor directly to your transmon? This gave you the correct jet mounting height and brought your prop within 1.5 inches of where it is supposed to be?
    Are the transom heights the same between the Sport Drifter and the Alaskan II?
    Tennessee

  12. #12
    Member akrstabout's Avatar
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    Default extra bolt in cavitation plate

    depending on how you buy your motor it may or may not have the bolt or hole drilled through the front area of the cavitation plate. had a jet boat and sold it and didn't have one. mechanic recomended one because makes the unit that much stonger and he said will hold the jet on if you hit a rock and the other main 4 bolts can rip lose. he has known of many cases that have happened. I think $75 if you bring the motor to them with the lower unit off and ready for them to drill. takes jig to drill and counter sink at the right angle of the top area of the plate. If you were looking at your motor from the back of the boat, would be the part you would hit your leg on. Our when it was running you could see water shooting out around there. I don't think it causes much power loss but made us realize it would be a good thing to get it done. But we just sold the boat and moved on. Just thought i would tell you just incase you didn't know. Not sure how it would affect a motor with prop after the jet is off. Oh my yamahas have rubber gromet there. Must be what that is. Plugs when changed over. Shouldn't allow water into lower unit of the prop set up. Ask your dealer or supplier you buy from about it. Or guys on this site. Hope it helps anyways.

  13. #13

    Default Directly to transom

    Snowwolfe,

    Yes, the motor is bolted directly to the transom, and yes, the lower unit is within 1 1/2" when it is installed. There is a riser welded to my transom to bring it to the correct height for the XXL shaft with the jet. It was cheaper to do that than to by the XL shaft Yamaha or Honda and the long shaft kit from Bay Manufacturing. Don't know for 100%, but I think the standard transom height on both boats is 25". My kicker is an XL shaft and is at the perfect height. This picture shows the riser welded to the transom.

    Keep in mind, this was all done to allow me to switch back and forth without having to use a jack plate or relocating the motor. It seems like it was a round about way to do things, but Glen worked it out and found that it was the cheapest way to go when I ordered the boat. They are a great bunch of folks to work with.
    Attached Images Attached Images

  14. #14
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    Default

    Eggy,
    I admit I am confused. Why did you need the XXL shaft and then weld on a riser?
    If you needed a motor mounted higher but the prop is still just a shade to high when mounted on the motor why not just do away with the riser or the XXL shaft?
    Couldnt it been easier to use just a XL shaft, and do away with the riser? This way the jet would of been mounted at the correct height and the prop would be in a better position as well.
    I just can not get a clear picture in my mind why this is needed.
    Another point, if you change out from prop to jet and vice versa do you have to install different cables?
    Tennessee

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    Default prop to jet and back

    ok guys, I see what your saying, and I understand why you went with the XL shaft. Heres my question. I just bought a boat with a 2003 merc direct inject opti on it. It is set up properly for the jet, but the guy threw in the lower unit with the prop too. Said I would need a jack mounted on there for them to both work properly. Said Marita had on for $1500 installed. A. If i go this route, what are good brands of jacks? who has one and likes it? B. is there a spacer kit(mentioned above, i think) for a merc and is that the way to go?

  16. #16
    Member AKBighorn's Avatar
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    Default

    I installed one of these on a friends boat. http://store.wmjmarine.com/87-3354.html It worked pretty slick. They also make the same model in manual operation. It takes a bit to move the motor manually but if you know where you want it set it may be worth saving $300-$400. Both the riser coupled with the extended shaft or the jack plate will simply make it easier to move the motor when switching lower units and elimating the need to use a hoist. I also saw this one for much cheaper http://www.overtons.com/modperl/over...3C&cID=FROOGLE
    Hope that helps.

  17. #17
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    Default

    I've got the manual power lift and you spend a lot of time cranking on the lift/lowering bolt. I wish I had splurged for the power model.

  18. #18

    Default Raising & Lowering Transom Jacks

    Couldn't the trailer jack be used to raise and lower the outboard? If you raise the tongue jack up all of the way, then block the outboard under the jet foot, loosen the slot bolts, then lower the tongue jack, that would lower the outboard. You could do it in reverse to raise the outboard.

  19. #19

    Default Yep....It's confusing!!

    Snowwolfe,

    The reason I needed the riser on the transom is because I went with the XXL shaft motor. The reason I went with the XXL shaft motor was to get the spacer. The reason I wanted the spacer was to avoid using a jack plate or having to re-mount the motor each time I switched back and forth. Follow that? I think I got it right. The spacer comes with the XXL shaft motor from Honda, but does not come with any other length motor. This set-up was purely a cost saving thing for me.

    You can avoid the riser on the transom by buying a long shaft motor, but then you'll have to buy an aftermarket kit like the one from Bay Manufacturing, or use a transom jack to mount the motor on. I didn't want the 630# that my motor weighs hanging any further off the transom than absolutely necessary and Glen Wooldridge told me that sometimes you can get cavitation issues when the motor is set that far back when using a jet unit.

    The motor needs to be mounted about 5 1/2" higher when running the jet unit as compared to the prop. That's why the spacer comes in to play. It gets the cavitation plate on the lower unit back down to the bottom of the boat where it needs to be. It's easier to see what's going on when you're looking at the boat and motor with both the jet unit and lower unit on hand. Once you see that, it's like a switch goes off and everything is clear.

  20. #20
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    Default

    Let me see if I have this straight.........I am guessing the shafts are avaliable in 5 inch in increments. if you would of used a shorter shaft motor then the prop would of been 3-4 inches deeper in the water than it should be?
    Thanks for taking the time to try to explain this.
    Tennessee

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