Announcement

Collapse
No announcement yet.

Waverunner XL-760 Top RPM ??

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
  • #1

    Waverunner XL-760 Top RPM ??

    Hello,

    I have a 1999 Yamaha Waverunner XL-760 that we just recently had rebuilt. Anyway I've noticed that it tops out at 6000 RPM and the speedo reads 41-43

    I remember it hitting speeds of atleast 50 back before it developed some engine problems... I don't remember what it's top RPM was back then... So what range of RPMs should I be expecting from this PWC?

    If it's supposed to top out at 6 grand then I'll leave it be because it's running great.


    Thanks--

    Kenny
    Tags: None
  • #2
    Re: Waverunner XL-760 Top RPM ??

    what is the compression? Compression = speed

    Comment

    • #3
      Re: Waverunner XL-760 Top RPM ??

      Actually, compression=low end power. Relatively lower compression actually gives better top speed (within limits) :)


      Top RPM should be about 6700, you are low. Does the ski have any mods? Who rebuilt it and exactly what was done? What caused the first failure and what other repairs were made? Have you tried fresh plugs? Do you know where the carb needles are set?
      SBT Tech Support is here to help with your problems.
      We try to answer each question quickly and accurately.
      Please do not use Private Messaging for Tech Support, use the forums.

      Comment

      • #4
        Re: Waverunner XL-760 Top RPM ??

        I thought it was revving a little low... Anyway It was rebuilt because of low compression on one of the cylinder. It was rebuilt by Yamaha Sport Cycles dealer in Athens, Ohio.

        I know before we had it rebuilt the carb needles were at stock settings. I think they were something along the lines of Low end- 1 1/4
        High end was close to 1/2

        We have two sets of plugs that we've tried in it so far. We have the recommended BR8HS and we also have tried some BR7HS in it. The 7's seem to make it pick up alot faster but it still doesn't rev up to 6700. It might hit 6100 with the 7's and around 5900 - 6000 with the 8's


        I don't have the work invoice that shows everything done to our ski with me. I would guess that it was bored out and they put new pistons/rings in it and they should have rebuilt the carbs and probably adjusted them back to stock settings.

        I haven't checked the carbs yet... we just had it out yesterday so the family could play on it and I'm sure they wouldn't have like it if I took it and started fiddling with carb settings. :)

        I have pulled the plugs after running WOT then killing it and they look fine.. Looks just like the pictures shown in the thread "Carb Tuning by reading the plugs"

        I'll have to check the needles and see where they are right now and if they're really far off I'll turn them back to stock settings (Have to find the post on this forum first though because I'm not 100% what the stock settings are) and I'll report back.

        Thanks--

        Kenny

        Comment

        • #5
          Re: Waverunner XL-760 Top RPM ??

          DO NOT use hotter plugs unless you want a hole in your piston. Plugs are not for tuning out a problem!

          Verify the screws are correct and also verify your throttle plates are opening fully - they may have misadjusted the throttle cable.

          Do a compression check and tell us what you get.
          SBT Tech Support is here to help with your problems.
          We try to answer each question quickly and accurately.
          Please do not use Private Messaging for Tech Support, use the forums.

          Comment

          • #6
            Re: Waverunner XL-760 Top RPM ??

            Well I have some good news and some extremely bad news...


            The carb needles were all out of whack... The low side was 2 turns or so and the high was like 3/4

            Anyway, I set them to
            Low- 1 1/4
            High- 1/2

            This is what my Yamaha dealer told me the stock settings were.

            Also I checked to make sure the throttle plates were fully functional and they were working fine.

            I took it out on the water and it revved up to 6800 fast so I was impressed. It ran for about 2-3 minutes then died.

            After we were towed back to shore I pulled the plugs (BR8HS were in it) and did a finger compression test.

            The front cylinder seemed to have good compression but the back cylinder had little to none.

            I've talked to my Yamaha dealer who rebuilt it and they're supposed to look at it on Tuesday - What a bummer to be on vacation at the beach and our jetski dies... I just hope they can get it fixed for the 4th of July. :(

            I'm hoping the rings on the rear cylinder just broke as that would be alot easier to replace than boring the cylinder more.

            I have no idea what caused this... :(


            Thanks for the help-

            Kenny

            Comment

            • #7
              Re: Waverunner XL-760 Top RPM ??

              Most likely something was not built or repaired correctly, sorry to hear that.
              SBT Tech Support is here to help with your problems.
              We try to answer each question quickly and accurately.
              Please do not use Private Messaging for Tech Support, use the forums.

              Comment

              • #8
                Re: Waverunner XL-760 Top RPM ??

                Yeah... I agree - I can't believe we payed $600 or so to get it fixed and it still isn't working right... How much would it cost to put one of your engines in my ski? $800+ ??

                Will the 760 Hull accept any larger engine - say an 800 or possibly a 1200?

                I'm sure that my dealer will fix whatever mess-up they had for free, I'm just trying to see what my options were.

                -Kenny

                Comment

                • #9
                  Re: Waverunner XL-760 Top RPM ??

                  You can't swap the block for anything else, you need all the other parts. That engine from us is $699.
                  SBT Tech Support is here to help with your problems.
                  We try to answer each question quickly and accurately.
                  Please do not use Private Messaging for Tech Support, use the forums.

                  Comment

                  • #10
                    Re: Waverunner XL-760 Top RPM ??

                    My dealer's blaming the reason our ski blew up was because it was too lean... He told Dad that the oil we use (Quicksilver TC-W3 Outboard Oil) is a thinner oil and therefore has to be mixed 40-1 instead of the 50-1 that Yamalube takes.... Should that be the case?

                    My opinion on why the ski blew up is because after it had been running for a while and they flushed it - the engine filled up with water (while it was shut off) and cracked a ring/piston/ whatever.

                    Comment

                    • #11
                      Re: Waverunner XL-760 Top RPM ??

                      No that makes no sense. It's 50:1 no matter the oil, and that has nothing to do with the mixture unles you put in 20:1 or some other extremely heavy mixture.
                      SBT Tech Support is here to help with your problems.
                      We try to answer each question quickly and accurately.
                      Please do not use Private Messaging for Tech Support, use the forums.

                      Comment

                      • #12
                        Re: Waverunner XL-760 Top RPM ??

                        Thanks for the quick response... I'll have to get Dad to call them up and get this straightened out.

                        Comment

                        Previous template Next
                        Working...
                        X