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  • 224 Not getting enough speed

    I just recently purchased a 1983 224. I had to replace one piston when I got it. Motor seems to run fine, but my top speed is 36mph at 5300rpms. I get 20mph at 4000rpm. It seems to be running too hard for only 20mph. The boat has a 97' Johnson 225 on a rebuilt composite transom, with a 30" Armstrong bracket. 14.5 X 19 SS prop. I'd appreciate any advice.
    JC

  • #2
    If after checking your compression on each cylinder and is good, I would look at how low the motor is mounted as it may be to low. Then try a smaller prop if the above is good.
    [br]Mako 241[br]Winter Garden, FL

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    • #3
      The new piston was 91#.

      The remaining pistons were between 70 & 73#'s.
      JC

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      • #4
        quote:


        Originally posted by JC74


        The new piston was 91#.

        The remaining pistons were between 70 & 73#'s.



        Im not a mechanic but I have heard many times they should be within 10% of each other. I'd guess the 70s pistons are running low.
        David, New Kent, Va[br]



        [br]Project Thread: http://www.classicmako.com/forum/top...TOPIC_ID=21067[br]

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        • #5
          I had a 1995 Yamaha 200 Salt Water Series on my boat....221 hull. It maxed out at 36 mph. While the boat should be a 40 mile an hour boat...it was never really a practical issue. You rarely need to open it up WOT. Perhaps just to check the rpms and clean out the carbon. 25 mph is fast on the ocean, depending on conditions, but i do understand the desire to get up to and north of 40 mph. Also do not want the engine to work that hard to deliver suitable speed. I felt the same way since 2002 when I got the boat After I repowered with Evinrude G2 200 HO, i was up around 43mph with better than half a tank and no gear, ice etc. Now the torque and power of the G2 for normal operations is significantly more responsive and much, much BETTER. Obviously no contest. That said the 200 Yamaha served me well. IT took me 30 miles off and back many times. It just topped out at 36 mph..and used fuel at an alarming rate.....on a good day. I would find the BEST mechanic money can buy and make sure the engine is reliable and run it. Now there are many intermediate steps u can take to try to improve your speed. May work may not. Wet foam, motor height, prop. I would do all those too. IMO
          EXPLRGAB 224/221[br]PORT ST LUCIE, FL

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          • #6
            I appreciate the information.

            It's not so much the top speed I'm concerned with. 36 mph is fine with me, however based on a lot of information I've read the top speed should be closer to 42-45 mph. It's the 20 mph at 4000 rpms that's my issue. I like to cruise around 20-25 mph. It seems as if the boat is working too hard to maintain the 20-25 mph and sucking up too much gas. This and the top speed being less than average makes me think not enough power, wrong prop, motor too low (it's in the second highest hole)

            I'm not sure. I know the compression is a little low but I don't think it's low enough to not produce enough power.

            Thanks again for your time and information.
            JC

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            • #7
              I believe your prop may be the issue. 20 mph at 4000 rpm is not good. That prop is probably to large.

              I have a Yamaha 250hp ox66 spinning a mirage 15x17. On my 231 . I run 25 to 27 mph at 4000

              Rpm. Wot is 43 mph at 5300 rpm.
              Brian Duff[br]1988 Mako 211-Sold [br]1991 Mako 231 special edition[br]2001 Yamaha 250 ox66[br]Toms River, NJ[br][br]

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              • #8
                Ive had 2 different motors and turned 3 different props on my 224, the only time I went down to a 17 pitch was when I was turning a 4-blade. With my old OMC 200 I had stainless 14.5x19, and when I had Prop reworked the local prop guy said that was right prop for my set-up. My 19 Enertia is perfect for current setup.

                I do think your numbers are low, but Im certainly no expert. Is the prop in good condition? Can you post pics, profile & transom, with motor down? Is it a 25 or 30 motor? Know where cavitation plate is under plane?
                \'93 241 https://forum.classicmako.com/forum/...etting-started
                \'82 224 - Mobile, AL Gone but NEVER Forgotten - https://forum.classicmako.com/forum/...indshield-tank

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                • #9
                  Slip is 49% at 4000 rpm and 29% at wot should be close to 10%. Could be hub slipping, motor height, trim, or bad prop.

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                  • #10
                    Slip is 49% at 4000 rpm and 29% at wot should be close to 10%. Could be hub slipping, motor height, trim, or bad prop. Are you running aluminum or ss prop?

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                    • #11
                      Good evening! Thanks again for the advice.

                      ChuckB- The prop is SS and in good shape. It came with a SS 14 1/4 X 21 but I tried a 14.5 X 19 that seems to be better. It has a fairly new solid (no cut out) composite transom with a 30" Armstrong bracket made for two motors but only has one. It has Bennett trim tabs. There's an aluminum plate between the tabs that seems to be extending the hull. I don't know what that is, if you do please let me know. The weird thing about that plate is, it's about sticks out 12" off the starboard side and about 16" off the port side. According to the paperwork it's has a 30" motor. It's in the second hole from the bottom (two more holes available to raise it, I believe). The water hits about 2"-3" above the cavitation plate when on plane. On the trailer the cavitation plate is about 2" above the keel. Sorry, I do have photos but can't seem to get them uplaoded here.

                      73mako22- Are you saying that I'm experiencing that much slippage? If so, that seems like a lot and did you come up with that?

                      Thanks Agian!!
                      JC

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                      • #12
                        Google prop slip calculator use 1.86 x 1 as gear ratio for your engine. Put in rpm and speed

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                        • #13
                          Could the extensions be causing turbulence causing air to mix with the water before getting to the prop? You indicate you changed prop and it helped some. Did you use same hub? If not that should eliminate hub slipping as cause. I would try dropping engine one hole to get cleaner water to prop.

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                          • #14
                            With the trim tabs up all the way does the bow ride high? If so the bracket may not be the correct one for your transom angle. I assume since you have owned it the problem has existed. If dropping one hole helps but not enough try a four blade prop. They will run better in turbulent water. Do you know for a fact that boat ran correct since transom work and bracket was installed?

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                            • #15
                              Use 1.86 not 1.86x1 in calculator

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