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86(39) 2450 Sunbridge - first time out-gctid390240

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    86(39) 2450 Sunbridge - first time out-gctid390240

    Well, I was able to get my 1986 Cierra Sunbridge out on the water for the first time. It has an AQ225 and ran well for the most part. I have a couple of questions that I'm hoping the community could help me with.

    First, what is the low idle RPM for this engine? It would run fine at about 800 RPM but throttle down any further and it would die. Even after the engine had warmed up it would do this. The previous owner had the engine rebuilt and it had only 40 hours on it when I bought it, so perhaps it just needs some adjustment.

    Second, it took a LOOOOOONNNNNGGGG time to get up to plane. I took this out on a local lake first, unloaded with just my brother and myself and it seemed like an eternity for it to get up to plane. I'm hoping to get up to Nootka Sound in a month and with gear and ice chests filled with salmon (hopefully) on the swim step, it might never get to plane. Like my brother said, and he has loads of boating experience, it acts like a pig trying to get up to plane but once it finally gets there it runs great and fast, about 32 mph. I'm curious what prop I'm supposed to have on it or perhaps there is something else that could be preventing it from planing quickly.

    This is my first Bayliner and it was awesome on the water. I can't wait to get it out in the sound soon.

    #2
    i have the same boat, mine had the aq225 in it and yes it is a big of a slug to get on plane. i always had someone head down in the cave untill it steps up. my trim tabs also never worked so im sure they would help. do yours work? i replaced the 305 with a 350 and it is alot better. im not sure what prop i have on there now i will have to look. mine runs about 38 mph on the gps. as far as putting anything on the swim deck i would forget about that. just a cooler of beer all the way aft would keep mine from getting on plane with the 305. one thing i did that helped alot was to move the batterys as far forward as possible. i also just fixed my trim tabs so when she goes back in the water next week cant wait to see the difference. i did a ton of work to mine over the past few years, incluing a new transom and stringers so i know this boat pretty good. if you have any questions shoot me a pm and i will try to help you if i can. oh and mine idles at about 700 rpm, not sure if thats right or not but like you said anything lower and it dies. goodluck

    Comment


      #3
      A few things will help.

      Have your trim tabs fully down. This will push the bow down. Once up on plane raise the tabs to reduce drag and increase efficiency. Have as little weight on the stern as possible. I do not belive you can trim your drive, but if you can make sure it is not trimmed up while getting onto plane. A 4 blade prop helps get you up on plane quicker, but it can reduce top end speed.

      By eternity, how long did it take? Also, what was your max RPM's at WOT.
      Phil, Vicky, Ashleigh & Sydney
      1998 3055 Ciera
      (yes, a 1998)
      Previous boat: 1993 3055
      Dream boat: 70' Azimut or Astondoa 72
      Sea Doo XP
      Sea Doo GTI SE
      Life is short. Boats are cool.
      The family that plays together stays together.
      Vice Commodore: Bellevue Yacht Club

      Comment


        #4
        On the idle issue, make sure your timing is correct. Timing can affect the idle, but if the timing is so far advanced that it dies at idle, you will usually see better enigne perforance, but you will also have detonation.

        My distributors (both of them) were frozen when I bought my boat, (no advance) and it idled terrible. Without a light, I adjusted the timing until it would idle, and it ran GREAT! Shortly after that i brough it to the shop for some tuning, and in order for it to idle, the distributors were at 30 degrees advanced!!! I replaced the distributos and lost a lot of low end perforance, but at least it is right.

        Having said that, I used to have a '79 Saratoga that had the same AQ225, and yes they are pigs getting out of the water. With 4 adults on board, a full fuel tank (100 gal), at sea level, it was barely able to get up. That engine was also replaced with a 350, and made a world of difference. The 305 ci Checy is a good engine, but Bayliner must have bought a traiload of them, and put them in a lot of their larger cruisers, but they were all under powered. Glad I have 2 of them in mine.

        Comment


          #5
          Thanks for all of the advice. I'll definitely check the timing. Right now, I can't remember the RPM's at top speed but I will note it on the next trip. I did use the trim tabs and they do work. As for time to plane, off the top of my head I would say about 30 seconds, give or take. It will be awhile now before I get it out again. The tilt failed on me and when the boat went in reverse, the outdrive came up. I need to work that problem out first.

          Comment


            #6
            Are you propped correctly?

            Are you able to reach WOT RPM?

            In order to test this, all ducks must be in a row:

            Bottom clean.

            Drive and prop clean and in good condition.

            Drive ratio correct for the engine (1.61:1 in your case)

            Engine tune.... including the correct progressive and total advance (this is extremely important!)

            Boat loaded correctly and as how you would normally load it.

            Only now can you perform a WOT RPM check!

            Agree..... the AQ225 is on the small side for this boat.

            Quick story;

            I once owned a little 24 foot SND F/B boat (dual station) years ago.

            AQ200 (5.0L w/ 2 brl carb) and with the 1.95:1 Duo Prop drive.

            This little guy flew. It would do just under 38/40 mph with just me O/B.

            I removed the Duo Prop, installed a single prop drive, and sold the boat.

            During the sea trail, I was almost embarrassed at how poorly it performed w/out the DP drive.

            You've got two choices if you want more performance, IMO;

            Larger engine..... or the Duo Prop drive!

            The 225 w/ the DP will do just about as well as would another 80 horse power w/ a single prop drive.

            .
            Rick E. Gresham, Oregon
            2850 Bounty Sedan Flybridge model
            Twin 280 HP 5.7's w/ Closed Cooling
            Volvo Penta DuoProp Drives
            Kohler 4 CZ Gen Set

            Comment


              #7
              800 RPM should be the base idle RPM. I would also check timing.

              You should be seeing 4400 RPM at wide open, and doing somewhere around 38 - 40 mph.

              THe 2450 is not a slug with the 225, since its a relatively light 24 footer to begin with. 30 seconds is unacceptable for a planing time, depending on how heavy you load it, you should be on plane and accelerating in 10 seconds or less.
              Matt Train
              BOC Site Team
              Chicagoland, IL

              Comment


                #8
                Assuming you have the 275 drive, no trim, but there is an adjustment on the transom shield.

                It has 3 holes On my Capri the middle hole is optimal . Your model might be different.

                I know it's a different boat but I get low to mid- 40's with full fuel & 2 or 3 people with the same engine / drive @ 4400 rpms

                Comment


                  #9
                  I had an '85 2450 sunbridge that had a 225 and currently own an '86 command bridge (heavier) with a 260. As previously mentioned, set the trim tabs all the way down before going up on plane. This will help the boat get up on plane faster. You can raise the tabs once up on plane (e.g. raise bow) for the best ride height, best, fuel economy, etc.... One thing I did/do not like about this size/vintage boat is that the trim tabs typically felt undersized as far as I was concerned. My 2450 wasn't "turbo charged" by any means with it's 225, but I don't feel it was overly slow or sluggish by any means. It certainly didn't take 30 seconds to get up on plane.

                  Comment


                    #10
                    When I did the test run, it was just my brother and me without anything in the boat. In fact, I have two batteries for the house bank and they haven't been installed yet but were in the bow where the table sits. The motor sounded great and we did have the trim tabs down when trying to get to plane. I think a tune up will do it wonders though and I will be getting it in next week for that as well as for the tilt problem.

                    I don't know the prop size that I have now, but I am interested in the duo prop. What size should I be looking at for this boat?

                    Comment


                      #11
                      MadViking wrote:
                      I don't know the prop size that I have now, but I am interested in the duo prop. What size should I be looking at for this boat?
                      Sorry, I'm not following your question. Single prop, or Duo Prop?

                      If single prop, you simply need to test props and perform the WOT RPM test.

                      To do otherwise, is a crap shoot.

                      If you add the Duo Prop lower unit, you'll need the 1.95:1 ratio.

                      Props to begin with will likely be the B-3's (aluminum) or C-3's (SS).

                      But again, you must do the WOT RPM test.

                      Here's an ignition advance curve for the Volvo Penta 5.7L.

                      The curve listed as "original" should work for your AQ225.

                      Note that the vertical scale (degrees) is minus BASE advance.



                      .
                      Rick E. Gresham, Oregon
                      2850 Bounty Sedan Flybridge model
                      Twin 280 HP 5.7's w/ Closed Cooling
                      Volvo Penta DuoProp Drives
                      Kohler 4 CZ Gen Set

                      Comment


                        #12
                        I noticed you said the tilt failed on you. Are you trying to trim the drive while under way? I might be reading it wrong but if you have the vp 275 outdrive on your 86 2450 like i have on mine it must be all the way down in its locked position. There is no trim on this drive. On the popping up in reverse, lots of us here have battled this problem. Make yourself very familiar with the reverse lock. It must be clean and move freely. Also the 2 hooks that lock it in place must be damn near perfect for it to work. I just replaced them on mine, it was tbe best 150 bucks i ever spent...lol there was a great post here awhile back that explains the whole thing and how it works. I would post the link but cant on my phone. Try doing a search im sure it will pop up. Goodluck

                        Comment


                          #13
                          cbr900rr wrote:
                          there was a great post here awhile back that explains the whole thing and how it works.
                          If you are thinking of Bob Case's thread, you can find it in the Vault.

                          Look for Bob Case's Reverse Latch thread in the BOC Vault thread titled http://"http://www.baylinerownersclu... & A&#39;s</b>

                          It is just a few links below the thread showing the prop shaft carrier puller tool.

                          .
                          Rick E. Gresham, Oregon
                          2850 Bounty Sedan Flybridge model
                          Twin 280 HP 5.7's w/ Closed Cooling
                          Volvo Penta DuoProp Drives
                          Kohler 4 CZ Gen Set

                          Comment

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