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Thread: Bottom line on OBJets

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    Member Yukoner's Avatar
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    Question Bottom line on OBJets

    So, what is the way to go for a larger outboard jet? 2 stroke or 4?
    I'm looking at a 150, either a Yammy 2s or a Yammy 4s. Don't want to lose performance. Will the big 4 stroke be that much better fuel consumption wise? Certainly will be quieter. Do the 4 strokes give up some power to an equivelant 2 stroke?
    In the 2 Yammys anyway, there isn't a lot of weight difference, only 40 pounds or so.
    Thanks gents
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    Member alaskanmoosehunter's Avatar
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    You will give up some quick hole shots if you go with a 4 stroke vs. 2 stroke. Hole shots aren't that important to myself. I would take a new 4 stroker in a heart beat to avoid paying for the new 2 stroker oils that they require. Power is the same it's just one has a faster power band than the other to a certain RPM.

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    I was told that Yamaha will discontinue all 2-stroke outboards at the end of this year. I don't know what that means for long-term availability of replacement parts or service. I don't think anyone knows. That alone would make the decision easy.

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    The next outboard jet unit I purchase will be a 4 stroke, the fuel economy is all I need to tip the scale that direction.

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    Mercury Optimax - 2 Stroke performance, better than 4 stroke fuel efficency...

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    Default Optimax Performance

    Agree with the last post. I have Wooly Sport with a 225 Opti. I average about 4.7 miles per gallon cruising at 27 MPH. This past weekend did a Whittier to Montague trip (238 miles total) and burned 50 gallons of fuel. After break in they sip the DFI oil.

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    Quote Originally Posted by OneLunG View Post
    Mercury Optimax - 2 Stroke performance, better than 4 stroke fuel efficency...

    You are correct..They are remarkable performers for efficency. However, the Honda 4 strokers are Amazing! I would like to see real life comparison between the 2 fuel wise and total cost to run them.

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    Quote Originally Posted by woolydriver View Post
    Agree with the last post. I have Wooly Sport with a 225 Opti. I average about 4.7 miles per gallon cruising at 27 MPH. This past weekend did a Whittier to Montague trip (238 miles total) and burned 50 gallons of fuel. After break in they sip the DFI oil.
    Is that with a prop or jet unit?
    Anyone run Yammy 4 strokes? The F150 gets great reviews.
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    Default propped

    Those are the numbers with the prop. Have not checked with pump on it recently, but am sure it is about 33% less efficient.

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    Quote Originally Posted by alaskanmoosehunter View Post
    You are correct..They are remarkable performers for efficency. However, the Honda 4 strokers are Amazing! I would like to see real life comparison between the 2 fuel wise and total cost to run them.

    AMH
    I can give ya one. When running down the Yukon and up the Koyukuk I run a 200 Opti, one guy in my group runs a 200 etec, and the other guy runs a 200 Honda. The Honda is whisper quiet and the Etec makes less noise than my Opti.
    But when we refuel I require less gas than either of them. Downside is the 2 stroke oil which my boat uses at about 50-55 to 1 when the boat is fully loaded and I am running it hard. Intersting observation is the guy running the Etec used to run a Honda but sold it because it took way to long to get his boat and load on step.
    Don't get me wrong, the 4 strokes are nice. But do not discount the DI 2 strokes. The Opti weighs in about 125 pounds lighter than the Honda and requires a lot less maintence.

    Personally I would never use a 4 stroke outboard as a jet platform unless the motor was really huge. For example, if I needed a 150 jet I would buy a 200 4 stroke. They are slow to spool up. They are great choices for crusing boats and such but make mine a 2 stroke if I wanted to add a jet to it.
    Tennessee

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    Having done a fair amount of jet-boating in skinny water in SE (Taku and Berners)

    We wont run 4-strokes on our boats. A lot of people hopped on the 4-stroke bandwagon hoping to save gas. In the long run they have switched back to 2-stroke because of weight, and hole-shot.

    I'd be willing to bet the Mercury Optimax is still the most FUEL efficient engine on the market.

    That being said, they make different hammers for different jobs - An optimax may not always be the best engine for a given job - I do however believe in an outboard jet setting, the optimax shines.

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    Wow. I couldn't disagree more. I just replaced a 2-stroke 50 Yamaha jet with the nearest comparable, a 4-stroke 60/40 Yamaha jet. There's no performance decline. In fact there's nothing but improvement. The new motor is quieter, smoother, has better controls, and has zero lag on the throttle response. Using the identical jet impeller the new motor jumps on step much better than the 2-stroke. Aside from price, the only possible downside of the 4-stroke is 60 pounds of added weight, and some of that is from the longer shaft. The old 50 sat on a 20" transom, the new one requires a 25". Enter the Specialty Jet adjustable transom bracket, which is a very nice piece of hardware. If I was on the cusp of having too much weight on the transom I may go looking for a 2-stroke. Aside from that? I think the 4-strokes have caught and passed the 2-stroke performance standard. For Yamaha's mid-size jet motors? I know they have.

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    Quote Originally Posted by Yukoner View Post
    Anyone run Yammy 4 strokes?
    I just picked up a F40 Jetdrive and although I have only ran two gallons of gas through it my ears already like it much better than the 200 Optimax it replaced. It spools right up without any lag and is much cheaper to run. I am done buying high dollar 2 stroke oil and am also done wearing ear plugs. Four stroke is the wave of the future as 2 strokes are all but outlawed. The zero vibration with the four stroke is also a big plus.

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    Default Pictures are worth a 1000 words

    Been running OB jets for 25 years and am a Merc Optimax fan... Great engine... But, I fitted my 19.5' army tug with a 155/80 Yamaha jet and am equally as happy. Kinda miss all the smoke though.

    Point being, both have there place, I guess it just depends on your preference and needs.

    Personally, if I was spending a lot of time far away, I would opt for a older simple 2 stoke so I could still work on them if needed, but all the engines today or too complicated for me so I like the 4 stroke,

    Good luck.

    [IMG]file:///C:/Documents%20and%20Settings/Tony/Desktop/My%20Documents/My%20Pictures/Alaska%209-07/DSCN2375%20%28Small%29.JPG[/IMG]
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    Quote Originally Posted by tzieli22 View Post
    Been running OB jets for 25 years and am a Merc Optimax fan... Great engine... But, I fitted my 19.5' army tug with a 155/80 Yamaha jet and am equally as happy. Kinda miss all the smoke though.

    Point being, both have there place, I guess it just depends on your preference and needs.

    Personally, if I was spending a lot of time far away, I would opt for a older simple 2 stoke so I could still work on them if needed, but all the engines today or too complicated for me so I like the 4 stroke,

    Good luck.

    [IMG]file:///C:/Documents%20and%20Settings/Tony/Desktop/My%20Documents/My%20Pictures/Alaska%209-07/DSCN2375%20%28Small%29.JPG[/IMG]
    THATS a load! Yamaha should use you as their poster boy for the 115 jet.
    Great info fellers, this is what i was looking for. Follows what i have heard Re. 4 stokes and jets. Yamaha seems to do the best out of the 4s's, while the Hondas less so.
    One thing i don't want to lose is that hole shot. Not being able to get on step in that short deep water stretch of river could really suck. I'd gladly have a noisier engine than a quieter one if that was the trade off.
    I really like this Yammy 115 2s my boat came with. Much more oomph to it than my 2003 115 FICHT i had on the old Alaskan. Might be able to find a good deal this winter on a 150 2s Yammy if they are going to drop 2s.
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    Member tzieli22's Avatar
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    Talking I agree

    Yukoner,
    I wish I could get Yamaha to call me back... Between the OB, ATV's and snowmobile I have with them, you would think they would talk to me.

    As for the hole shot, I agree it is very important and I don't know that I lost a lot if any going to the 4 stroke. Even with my former merc's I would add weight to the bow (move people there) if I was in a tight spot and I have always worked out okay. Now that I say this, watch, I'll get jammed up someplace... What I really do is make sure my jet sleeve and impeller are tuned as best as they can be and I am very pleased overall.

    The only time I had an issue getting on step was this summer, I pulled a 20' smokercraft up the big sue that lost his 140 Johnson. With the 6 people in my boat, plus pulling his boat, + 2 more people, + his 140 gal of fuel, I couldn't get on step... Go figure

    Good luck and help a fellow boater out when you can.
    Tony

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    Quote Originally Posted by Mr. Pid View Post
    Wow. I couldn't disagree more. I just replaced a 2-stroke 50 Yamaha jet with the nearest comparable, a 4-stroke 60/40 Yamaha jet. There's no performance decline. In fact there's nothing but improvement. The new motor is quieter, smoother, has better controls, and has zero lag on the throttle response. Using the identical jet impeller the new motor jumps on step much better than the 2-stroke. Aside from price, the only possible downside of the 4-stroke is 60 pounds of added weight, and some of that is from the longer shaft. The old 50 sat on a 20" transom, the new one requires a 25". Enter the Specialty Jet adjustable transom bracket, which is a very nice piece of hardware. If I was on the cusp of having too much weight on the transom I may go looking for a 2-stroke. Aside from that? I think the 4-strokes have caught and passed the 2-stroke performance standard. For Yamaha's mid-size jet motors? I know they have.
    You also went up another 10 hp which is a 20% increase over the old motor you used to have. No wonder you didnt notice any loss of performance. 4 strokes are good motors but they are not the best choice under all circumstances which is why sales of Etecs, Optimax, and the Tohatsue DI motors are selling so well. Less parts, less weight, less maintence, usually lower emissions and quicker to rev up. Trying to compare a old style 2 stroke to a newer DI model is like apples and oranges.
    Tennessee

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    Yep, the new engine has a little higher output. But I took that into account. I've been running jet boats for a long time and have a pretty good grasp of what's what. I don't have any criticism of the big 2-strokes. I loved my 200 Merc for the years I ran it. I've liked the 50 Yamaha, too. And the crop of other 2-strokes I've had and still have. But many of you made blanket statements that 4-strokes don't get out of the hole like 2-strokes like it's a fact. Well, it isn't a fact. In the case of mid-sized Yamahas it's completely incorrect. And that's from a guy who's run both motors on the same boat within the last week. I thought that was a pretty good testimonial. One boat, one driver, two motors.

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    Member akjeff's Avatar
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    Quote Originally Posted by Yukoner View Post
    So, what is the way to go for a larger outboard jet? 2 stroke or 4?
    I'm looking at a 150, either a Yammy 2s or a Yammy 4s. Don't want to lose performance. Will the big 4 stroke be that much better fuel consumption wise? Certainly will be quieter. Do the 4 strokes give up some power to an equivelant 2 stroke?
    In the 2 Yammys anyway, there isn't a lot of weight difference, only 40 pounds or so.
    Thanks gents
    If I were picking a new jet, I would consider the size of the pump first and foremost over hp or 2 stroke vs 4 stroke. (This does not apply to Suzuki DF140, with the offset, gear reduced drive shaft, because it is spinning the largest 7 5/8 impeller at a reduced RPM, 1.24:1 to be exact). The 150 Yamaha 4 stroke spins a 7 3/8 impeller, the 200 spins a 7 5/8 impeller. Depending on the size of your boat and the anticipated loads, bigger is usually better. Not only that running at 4500 RPMs with a 200+ hp probably beats running at 5500 RPMs with 150hp. I would choose the motor, spinning the largest impeller with the best fuel economy to weight ratio. Someone smarter than me could put together a formula, factoring in weight of the outboard and fuel economy. For me 100 lbs is a big deal when I am maxed out with meat on the return trip. The hole shot is important in really skinny water, but for me long haul, heavy load, fuel economy means more.

    Yamaha
    4 stroke weight
    150hp 466 lbs 7 3/8" impeller (AW)
    200hp 583 lbs 7 5/8" impeller (AQX)
    Evinrude
    2 stroke
    150hp 418 lbs 7 3/8" impeller (R6)
    200hp 418 lbs 7 5/8" impeller (R6-92)
    Honda
    4 stroke
    150hp 485 lbs 7 3/16" impeller (AY)
    200hp 588 lbs 7 5/8" impeller (AV)
    Mercury
    2 stroke
    150hp 431 lbs 7 3/8" impeller (S200)
    200hp 497 lbs 7 5/8" impeller (S200P)

    These numbers are from the following websites and the manufactures websites. I am not endorsing any one brand or 2 vs 4 stroke. The same comparison can be made with any or all the manufacturers. I just chose these. I run a Suzuki DF140 on a 24 ft boat. When I repower I will have a hard time not getting a 200hp 2 stroke. In my opinion the numbers are good. Then again there are always the intangibles, like reliability and longevity etc. etc.



    http://www.outboardjets.com/jetDrive...Web%202008.pdf

    http://www.outboardjets.com/jetDrive...Web%202008.pdf

    http://www.outboardjets.com/jetDrive...Web%202008.pdf

    http://www.outboardjets.com/jetDrive...Web%202008.pdf

    http://168.143.27.144/catalog/2008/L...LINER%20ID.pdf

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    We will have to agree on disagreeing then. I've personally watched the big 4 strokes (both props and jets) labor getting there loads on step while the same size 2 strokes were on step NOW.
    Granted I was not able to weigh them, etc. But I seen the 2 strokes do it often enough that it caused me to buy the Optimax for my boat. As well as it caused my friend to sell his same sized Honda (200) and replace it with the Etec.
    For my use, I love the quicking reving motor and the higher fuel economy of the DI 2 strokes.
    Tennessee

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