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Thread: Yamaha outboard Jet 115/80 questions

  1. #1
    Member tzieli22's Avatar
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    Default Yamaha outboard Jet 115/80 questions

    Well I am in the process of fitting a 115/80 Yamaha onto a old military pontoon boot and getting back into jets plus now Yamaha outboards. So far I am using a CMC jackplate (manual lift) and that is about it. My questions are any insight into
    1. SS impellers and sleeve, if so where
    2. Any insight into Yamaha 115/80 jet (likes or dislikes, tips etc)

    Thanks,

  2. #2

    Default I have a 2005 Yamaha OB Jet

    My yamaha is a great motor. Very quiet, reliable so far, and easy starting. That said I would NEVER buy another 4 stroke OB Jet. The 4 stroke is a real dog and is very heavy. If you havent bought the motor yet, I would think strongly about getting a 2 stroke. The 4 stroke on my boat is one of the reasons that I am selling it now. I am not trying to bash yamaha, on the contrary I believe they are the best built outboards around. It is just that, in my experience, 4 stroke motors give very sub par performance in a jet application.

  3. #3
    Member MARV1's Avatar
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    Default

    Jet performance all depends on the weight of your boat since you lose so much hp using a jet unit. 4-strokes also need to be run at about 500rpm higher than a 2-stroke. If weight is an issue then Suzuki's are the lightest 4-strokes around. Yamaha's are much better built though.
    The emphasis is on accuracy, not power!

  4. #4
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    Default take a look at the E-tec

    2strokes are much better out of the hole. My merc opti works great, I would get another one as this one has run flawless, but I would also seriously look at the evinrude E-tec. The E-tec is much quieter than mine weighs a little less, and has a longer wareenty. It's worth a look

  5. #5
    Member tzieli22's Avatar
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    Default

    Thanks for the input, well, I am Merc die hard but have decided to try 115 Yamaha. Weight shouldn't be to big an issue for this boat, but I am 2 or 3 days away from a water test. Thanks again.

  6. #6
    Member tzieli22's Avatar
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    Default Just an update

    Well folks, I have to tell you, I have been using my 115/80 jet and I have to tell you I am very pleased with the performance. I am able to get on step on 1 to 1 1/2 boat lengths with no issues. I seem to be burning 5.5 to 6 gph running any about 4300 to 4800 rpm's. I get it to about 33 mph (via GPS) going down the big su and 26 up river. I don't know, but I am pleased with the motor performance. I am an old Merc optimax guy but I am not unhappy with this motor. And as for the increased weight, it is about 85lbs more than the two strokes. (Not to big an issue to me.)

    Next question is on these new motors though, if and when you hit bottom the engine foot takes all the brunt of the impact i.e. the engine doesn't lift up out of the water like the older outboards did. Any insight on this (besides don't hit the bottom.. I ran up the Deshka several times and trying to be a nice guy, I was going to go around the fishing folks and it cost me pulling rocks out of the jet (some of it is just getting back into river running) but it did cause me to repair my impeller with my buddy's help, and buying a new one so know more nice guy here.

    Thanks for your help/comments.

  7. #7
    Moderator Paul H's Avatar
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    Default

    The only problem I've heard about the yamaha 115 is some of them "make oil" Translation, fuel blows by the rings and get's in the oil, thus increasing oil level. This is supposedly caused by running in cold water and not getting the engine hot enough for the rings to properly break in and seal.

    For the same weight of the yammy 115 (10 pounds heavier) you can get a suzuki 140, which would thus be a ~105 jet. I've yet to hear anything bad about the 140 suzi's, and I'm quite happy with mine, though I'm running a prop.
    Last edited by Paul H; 08-30-2007 at 11:20. Reason: added info

  8. #8
    Member tzieli22's Avatar
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    Default

    Thanks for the input. I know they have made good progress over the years. We'll see how things go over hunting season but it sounds like both are good choices. More to come I think.

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