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Looking for the lightest 75-90 HP outboard option.

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  • Looking for the lightest 75-90 HP outboard option.

    I bought 16' Fisherman by Sportcraft.a couple years ago and I have clean it up quite a bit. Perfect little bay boat for our family. Came with a 1991 3 cyl 75HP 2 stroke Mercury on it. It runs pretty well considering its age but since I bought it I couldn't get over how physically large is seems to be compared to some of the other outboards I have seen... in some cases larger that some 90's and 115's I have seen.

    Adding to this has been the fact that it seems to really weigh down on the stern of the boat. If anyone stands toward the back of the boat, water comes in through the scuppers. I installed ball check scuppers this year but the don't seem to work all that well (that's another issue).

    So I have been trying to do some research on:

    A. How much does the outboard I have weigh?

    and

    B. Is there a lighter alternative in a 75-90HP outboard out there?

    I saw some that came in around 200-230lbs and I "think" my motor is over 300 lbs.
    Last edited by Tesno; May 29th, 2017, 03:03 PM.

  • #2
    That 75 is the same as the 90 Merc, so being the lowest HP rating for that block hurts.

    ​The Yamaha 2 stroke 90 is the lightest and a popular motor, I'm not too sure how easy they are to find now.

    Comment


    • #3
      That's what I figured.

      Even within that power range it seemed like it was one of the heavier blocks compared to others.

      Just wanted try and find some hard numbers before I tried to buy a fixer upper in a lighter outboard motor and make a project out of it.

      Comment


      • #4
        You can find the weight of most all outboards on the nada site.
        They change year to year as the motor is redesigned.

        http://www.nadaguides.com/Boats/Outboard-Motors

        There are a few older motors that are around 250#, but most are going to be 300#.
        Medford, WI


        Comment


        • #5
          My C90 Yamaha 2 stroke premix motor is 268 lbs.....good HP per lb. of motor....

          Comment


          • #6
            Thanks for your replies. Think I will keep my eye out for that 90HP Yam. Cant go wrong with a little less weight and a little more power.


            Keeping oil injection in mind, are there any years to stay away from or to look for specifically?


            Also, I did see that Evinrude made a 75HP motor in 1985 that was only 198lbs! It was just that one year and model I think and I confirmed it in that NADA listing. What was with that??

            Comment


            • #7
              Evinrude made a 75 hp from about 1978-1989. They only made it on the 49 cid powerhead and was really designed for a lighter weight boat. The weight you saw was probably for the shortshaft version the long shaft weighed about 230 without power T/N/T. The Yamaha 90 hp is a really good motor my dad bought one brand new in 1985 and still has it. The 90 yamaha will not be much if any of a power upgrade over your 75 hp merc. My choice would be a 70 hp evinrude 1990 or newer I think it is the best compromise between the merc and the yamaha. I have experience with all 3 of these motors here are my observations: The yamaha is a fantastic motor good on fuel but does not have great low end power best best oil injection in the business. . The 75 Merc is also a great motor harder on gas and heavier than the Yamaha but overall a good motor. The 70 hp evinrude has power comparable to the 90 yamaha at #250 is the lightest of the 3 also the easiest to find parts for. The oil injection on the evinrude depends if you like the VRO or not

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              • #8
                Wow, so that much difference in how they rate there power? So your saying that the Evinrude 70 would give me as much power as the Yam 90 (on the low end anyway)?

                Comment


                • #9
                  Originally posted by Tesno View Post
                  Wow, so that much difference in how they rate there power? So your saying that the Evinrude 70 would give me as much power as the Yam 90 (on the low end anyway)?
                  The Yamaha is rated at 5500 rpm the Evinrude is rated at 6000. Years ago Bass and Walleye Boats did a dyno test on the yamaha 90 and I believe it made 81 hp at 5500 rpm they overreved it to 6000 and it made 91 hp. I don't believe you need to change your motor you have a good one. I ran a 70 hp evinrude on a 16' starcraft ss. It did 40 mph with me #220s my dog #100s 15 gallons of gas and a 15 hp kicker motor with 3 batteries and everything else I brought. Add another person and I was still at 38 mph.

                  Comment


                  • #10
                    OMC introduced the 49 cu in. 75hp in 1975, It was rated at 5500 rpm and had an approved Full throttle range of 5200 - 5800 rpm. 198lb short shaft, 220lb long shaft
                    The lightest 90 hp I ever saw was a 1976 Mercury 650XS. It was a 49.8 in. block, rated 90HP, WOT range was 6000 - 7000 rpm, and it weighed 180lb.

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                    • #11
                      Originally posted by flyingscott View Post
                      The Yamaha is rated at 5500 rpm the Evinrude is rated at 6000. Years ago Bass and Walleye Boats did a dyno test on the yamaha 90 and I believe it made 81 hp at 5500 rpm they overreved it to 6000 and it made 91 hp. I don't believe you need to change your motor you have a good one. I ran a 70 hp evinrude on a 16' starcraft ss. It did 40 mph with me #220s my dog #100s 15 gallons of gas and a 15 hp kicker motor with 3 batteries and everything else I brought. Add another person and I was still at 38 mph.
                      Thanks, I think I have a good motor but would love to look at knocking that weight down by 50-100lbs if possible.

                      Comment


                      • #12
                        Originally posted by jimmbo View Post
                        OMC introduced the 49 cu in. 75hp in 1975, It was rated at 5500 rpm and had an approved Full throttle range of 5200 - 5800 rpm. 198lb short shaft, 220lb long shaft
                        The lightest 90 hp I ever saw was a 1976 Mercury 650XS. It was a 49.8 in. block, rated 90HP, WOT range was 6000 - 7000 rpm, and it weighed 180lb.
                        I would LOVE a 200lbs 75 HP motor if it carried a descent rep and was oil injected. How many years did they make that?

                        Comment


                        • #13
                          Originally posted by Tesno View Post

                          I would LOVE a 200lbs 75 HP motor if it carried a descent rep and was oil injected. How many years did they make that?
                          You cannot use the Johnson 75 hp shortshaft motor on your boat for one they are rare and expensive, #2 is they used less than durable lower units on them,#3 they were designed for ultra-light weight boats not runabouts. It would be a waste of money that would cause more problems than cure. The 650xs is a straight-up race motor and expensive if you can find one. A 70 hp 1990 or newer will save you 20-50# that is the best you will be able to do.

                          Comment


                          • #14
                            Are you sure the boat sit low at the stern due to the motor weight? You could have waterlogged flotation foam, which is common on older fiberglass boats. Those 3cyl Mercs were pretty light motors to begin with. If your looking to upgrade...I would look for a 1999 and newer 90 Merc 2str 3cyl.

                            Comment


                            • #15
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                              Originally posted by fishin98 View Post
                              Are you sure the boat sit low at the stern due to the motor weight? You could have waterlogged flotation foam, which is common on older fiberglass boats. Those 3cyl Mercs were pretty light motors to begin with. If your looking to upgrade...I would look for a 1999 and newer 90 Merc 2str 3cyl.
                              Thanks for that thought. All good there though. When I first got her the fuel tank was fouled so I did a complete overhaul of the tank entire fuel system and all was good in the hull stern.

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