Yamaha 90 hp. four stroke

Discussion in 'Boating' started by duckalot, Feb 23, 2007.

  1. duckalot

    duckalot Well-Known Member

    Messages:
    1,971
    State:
    Missouri
    OK someone help me out. I found a 20 foot seaark with
    with a 90 hp. four stroke Yamaha and i think its worth the money. I know the seaark is a great boat, but lets here everyones opinion on yammies four stroke motor. The wifes gonna kill me but I think I going to come home with it tomorrow. So let me know what you think.
     
  2. loanwizard

    loanwizard Well-Known Member

    Messages:
    3,297
    State:
    Coshocton,
    I hope everyone likes it because I have a 2072 w/ a 115 yamaha 4 stroke jet that I'm picking up from Cooks this coming weekend or next.
     

  3. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    Good motor as most of them are. I think its a 10mm wrench you need to drain the carb bowls after every use.
    If it doesnt have a tach, buy one.

    Take good care of it, I doubt you want the bill for a rebuild on a 4 stroke.
     
  4. Mr.T

    Mr.T New Member

    Messages:
    2,553
    State:
    MO
    Huh??? Yamaha 4-strokes are fuel injected.

    But as far as quality and reliability, the Yamaha is an excellent engine.

    Follow the recommendations in the owner's manual to the letter, especially regarding the break-in period. I'd also suggest that you use Yamaha's Ring-Free fuel additive from the very first day - us 1 oz to 10 gals of gas, a quart will last you a really long time.

    One thought however: I'm certain you'd be a lot happier with a 115 on that 20ft Sea-Ark. The 90 will leave you wishing you had something bigger the first time you load it with more than just yourself...
     
  5. duckalot

    duckalot Well-Known Member

    Messages:
    1,971
    State:
    Missouri
    Thanks for everyones help. It is a used boat and motor so I don't have the option to go bigger yet.
     
  6. crazy

    crazy New Member

    Messages:
    2,090
    State:
    Kansas CIty, MO
    I just got a 115hp. So far so good. I really doubt you will see a real noticeable gain between a 115 and a 90hp. Only real difference is with the 115 you get little bit more displacement with the added weight with it.
     
  7. special liberty

    special liberty New Member

    Messages:
    295
    State:
    Maryland
    I run a 115 4 stroke Yamaha on the back of a 21' Carolina Skiff that is loaded to the gills with gear and accessories. I get 41 mph by gps in that big ol glass boat and I don't think I want to go any faster. No reliability issues as all - I love it. I think you'll be very happy with a 90 HP on a jon.
     

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  8. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Carburated or fuel injected, the 10 mm wrench or socket is needed to drain the carbs, or as in the fuel injected, the vapor seporator, which works similarly to a carb.

    Ring free and a good fuel stabilizer are recommended, but most importantly in the use of a 4 stroke, be sure it has a fuel/water seporator added before the gas gets to the engine. Don't trust the red ring in the engine filter. It'll float when the filter gets water in it, but it might be too late.

    I repaired a 115 4 stroke Yamaha this past summer, that had set for a few years in a warehouse. Nothing fuel related worked. A dealership would've replaced all the injectors and high pressure pump in the vapor seporator, adding the best part of 1000.00 to the bill. I treated the whole fuel system like a fouled carb, cleaning and electricly activating the parts until I got them all working properly. Reassembled it and so far, it's been trouble free. I get lucky sometimes:roll_eyes:
     
  9. olddriller

    olddriller New Member

    Messages:
    260
    State:
    Missouri
    Rob. We have a new 70 h.p. 4 stroke Yamaha , with a prop not a jet drive. It is on a 18x60 G-3 boat. This motor is doing a great job for us. Its very quiet, planes the boat real fast, does a good job of slow trolling, and pushes the boat plenty fast, the gas mileage is the best part VERY GOOD. Starts fast, in cold weather you need to let the motor warm up a bit befoure you take off.
    Good Luck
    Paul ( Olddriller) Retired
     
  10. 710split

    710split New Member

    Messages:
    31
    State:
    iowa
    We bought a new 19' Jon boat last year with this outboard on it.

    So far, with 115 hours, it has been really nice. It took too long to get used
    to the extra power which caused some interesting events.

    The break-in was NOT according to the manual. My dealer told me to ignore the manual. When all of the mechanics get together to chat, they decided
    there were too many problems during the break-in if you follow the manual.
    They tried to get Yamaha to change the manual and while the mechanics
    agreed, they couldn't get management to buy into their idea.

    Anyway.... during the 10 hour break-in period, they used a "cheaper, more
    common oil" that allowed more friction during the break-in period. This was
    to help get the engine up to running temperature faster and cause a little
    more wear on the internals. We were told to get the motor up to temperature
    by running for 5-10 minutes at 3500-4000 rpm. (( They were having pre-mature engine failures by following the manual which didn't allow getting the
    engine up to temperature causing improper (or not enough) wear during the
    break-in period. )) Once the engine was hot, we kept the rpm's below 4000, didn't run too long any one time at a single rpm/speed, and varied the speeds
    frequently for proper wear.

    Towards the end of last season, there was a funny sound from the engine at
    lower rpms. It sounded like a rubber o-ring that was dry and "squeaking". It
    went away at increased rpms. I'll be keeping a close eye/ear on this and
    try to determine what is going on this spring. (I'll also see if the dealer has
    any idea what it might be.)
     
  11. Mr.T

    Mr.T New Member

    Messages:
    2,553
    State:
    MO
    I don't think I'd mention that when the engine throws craps and you're trying to get Yamaha to give you warranty coverage... :roll_eyes:

    When I bought the Yamaha 60hp 4-stroke that was originally on my boat, the dealer's mechanic tried to tell me to "just run it wide open for an hour or so" and consider the break-in period complete. Brilliant! Why bother with all the cumbersome time and RPM restrictions in the manual when you can just grip it and rip it! So I put in a call to Yamaha and spoke with some very technical folks there, confirming that the dealer's mechanic didn't have a clue.

    When it comes to a choice between listening to the engineers who designed and built the motor or the grease monkey at the local boat dealership, I'll choose the engineers. At least then if I have a problem, I can be assured of getting warranty coverage since I followed the factory guidelines to the letter.
     
  12. duckalot

    duckalot Well-Known Member

    Messages:
    1,971
    State:
    Missouri
    Well shes mine! I just got home with my boat. Super clean boat.
    I will post the details on the Missouri fourm. Thanks for your help guys!