pxctoday

» Log in

User Name:

Password:

Not a member yet?
Register Now!

» Find OEM Parts

» Jobs

» wallpapers

Page 1 of 17 12311 ... LastLast
Results 1 to 10 of 168
  1. #1
    Top Dog bandit88's Avatar
    Join Date
    May 2014
    Location
    Two Rivers WI
    Age
    29
    Posts
    1,698

    New Project, JS Conversion freeride ski

    So I picked up a 440 hull with a 550 today. Planning on making a 750 conversion ski for more freeride. I have enough top end skis lol.
    Plans are RHAAS 750 pump conversion. 750 SP cylinder on BP bottom. Cylinder ported for more bottom/mid. Will have some sort of hull reinforcement.

    Thoughts / Questions:
    - Can a kawi 750 have the low end snap of a yami 760?
    - Anyone run a Solas or Skat pump in their conversion?
    - Shorten Pole? -2"
    - Hull mods? Rockered front, shortened length?
    - Pipes? Dont want to run a 650 pipe, thinking Coffman rocket with hull modified to fit.
    - Best way to clean bilge to prep for enamal?
    - Tubbies?
    - Rear sponsons: keep, ditch, or re-position?
    - Trim?
    - Best footholds?
    - Waterbox/ exhaust out: rear exit? dual front exit? Best waterbox that fits?
    - Thinking dual 44s
    - Intake grate

    Just spitballing, lots of thoughts going around im my head. Plan on doing this right. Hull will remain mostly stock looking. Going for a fun ski to ride, jump waves, etc. First steps are to get the hull cleaned up. Then looking at getting the rhass conversion to see how to pump installs and see if there is any room to shorten things a inch or so. Much more to come!



    -95 750SXI
    -86 440 undergoing PJS800 conversion
    -90 TS650

  2. #2
    PWCToday Guru Bob Gruen's Avatar
    Join Date
    Jun 2013
    Location
    Atlanta, Ga
    Posts
    496

    Re: New Project, JS Conversion freeride ski

    No reason a Yamaha 760 would 'out thrust' the Kaw 750 on the low end. It is probably more important to get the impeller (and pump) just right to get the arm wrenching performance you are looking for.

    As far as the pipe is concerned I wouldn't be afraid of a 650 pipe, but I would look for a stainless steel body that I could cut off the 1 7/8ths" end and have a full 2" end welded on it as well as a full 2" water box and outlet. I cringe every time I see a bulge modded in under the bond line as it kills handling.

    You seem to have the stock fiberglass water box, they can be split open and modified fairly easily. Would not be hard to remove the inlet and outlet and have 2" stainless versions made to bond back in. Rear exhaust is best, but Kawasaki puts a hump in the 550SX gunnel to keep water from intruding into the exhaust system. Aftermarket systems are straight and can load up with water when the engine is not running

    Dual 44s are on the big side for what you want. You need to keep the air velocity up through the carb for low end grunt. Larger carbs are more for top end, sacrificing low and mid for overall top end performance. Kawasaki put dual 40mm Keihin carbs on the 750, and if you read up on a few threads on this forum you will find that they work really well with a little bit of work. Full disclosure: people generally don't like them so you can find them cheap if they are not already on the engine. You may actually get more low end grunt out of dual 38s, but it would be a bit of an experiment and probably not worth messing with.

    Bob

  3. #3
    Top Dog bandit88's Avatar
    Join Date
    May 2014
    Location
    Two Rivers WI
    Age
    29
    Posts
    1,698

    Re: New Project, JS Conversion freeride ski

    Hey bob, I actually just sold a set of Kehins from my sxi and a set of SBN40s for a SXR. Wishing now I still had the 40s haha. I have so many parts for mikunis, and like them better, I dont ever see myself running keihins again unless its a stock ski that needs no adjustment. I was thinking dual 38s but I already have a 44 mani and all of the skis Ive rode that had good bottom had 44s. Thats a long way out so we'll see what happens when I get there.

    Definitely agree with the 2" exhaust and am thinking of modding the waterbox so it has outs on both sides then running stock through hulls on both sides with the old school tubes that bring it below the waterline. Should be a easy set up and will look cool IMO. Have you ever modded the fiberglass box before? What is the best way to adhere a out tube? Just mix up some thick epoxy and glue it in?
    -95 750SXI
    -86 440 undergoing PJS800 conversion
    -90 TS650

  4. #4
    PWCToday.com Is My Home Away From Home TheJS440's Avatar
    Join Date
    Jun 2014
    Location
    Seattle
    Posts
    2,049

    Re: New Project, JS Conversion freeride ski

    Subbed. Can't wait to see the build.

    All the freestyle boats have really short poles, and hulls, but they are lighter and wider.
    78 JS440
    -Ocean Pro Finned Ride Plate
    -Westcoast Intake Grate
    -SCR Ported Cylinder
    -Westcoast Exhaust Manifold + Pipe
    -Mariner Waterbox
    -Primer
    -SBN44
    -Quick Steer
    -Skat~Trak 16.5 SS Impeller

  5. #5
    PWCToday Guru Bob Gruen's Avatar
    Join Date
    Jun 2013
    Location
    Atlanta, Ga
    Posts
    496

    Re: New Project, JS Conversion freeride ski

    Bandit,

    3M has several adhesives for bonding metal to fiberglass, they are a bit different than normal epoxy. You could also go with J.B. Weld I suppose, it is specifically formulated to stick to metal. Not sure about it's resistance to solvents though. Whatever you use must specifically bond to metal and must be solvent-proof when cured. Exhaust gas will break down many resins over time and you do not want your box splitting on you while you are riding. Mine did; even the factory adhesive broke down over time.

    Bummer about unloading those carbs, either set would have been ideal for your build.

    Bob

  6. #6
    Top Dog Rompn's Avatar
    Join Date
    Aug 2004
    Location
    La Crescenta, CA
    Age
    35
    Posts
    1,495

    Re: New Project, JS Conversion freeride ski

    The RHAAS boat lost about 4" off the nose from the rocker and another 4" off the rear with the factory extensions removed. So -8" total. It is a pretty short boat and always wants to pencil air. I would do the rocker but keep the stock length in the rear.
    I would also go Yami with the engine for sure and run X-2 trim flipped upside down.
    The hoods love to pop off these boats in the surf with factory strap, I even sunk the RHAAS boat at Liquid Militia's Team Weekend last year and it has a surf strap. So in addition to the surf strap I would extend the hood to hull opening up in the corners.
    Use a limiting rope on the pole as well.
    Patrick Goldsworthy
    Region 1 / Vintage Ski / #28

    Chris "Fish" Fischetti & Victor "The Slasher" Sheldon



    RHAAS Freeride Machine / JK Pismo Freeride 2015

  7. #7
    Top Dog bandit88's Avatar
    Join Date
    May 2014
    Location
    Two Rivers WI
    Age
    29
    Posts
    1,698

    Re: New Project, JS Conversion freeride ski

    Quote Originally Posted by Rompn View Post
    So in addition to the surf strap I would extend the hood to hull opening up in the corners.
    Appreciate all the insight! What do you mean by this?
    -95 750SXI
    -86 440 undergoing PJS800 conversion
    -90 TS650

  8. #8
    Top Dog Rompn's Avatar
    Join Date
    Aug 2004
    Location
    La Crescenta, CA
    Age
    35
    Posts
    1,495

    Re: New Project, JS Conversion freeride ski

    Quote Originally Posted by bandit88 View Post
    Appreciate all the insight! What do you mean by this?
    The hood to hull area is pretty large compared to today's freeride boats. They tend to bend and flex easily because of how large they are. Land a 550 on it's side in the surf from altitude and you will knock the hood loose and sink the ski.
    Back in the day, JETTRIM used to sell little metal extensions that bolted onto each corner of the hull to hood area to help prevent this. You can make your own instead and also look into some latches like "KAHUNA" used to sell for the sides of the hull to hood as well. Along with a surf strap instead of the OEM latch and you'll be doing pretty good. I personally use a ratchet tie down wrapped around the entire ski/hood to keep it on.
    Patrick Goldsworthy
    Region 1 / Vintage Ski / #28

    Chris "Fish" Fischetti & Victor "The Slasher" Sheldon



    RHAAS Freeride Machine / JK Pismo Freeride 2015

  9. #9
    PWCToday Guru Bob Gruen's Avatar
    Join Date
    Jun 2013
    Location
    Atlanta, Ga
    Posts
    496

    Re: New Project, JS Conversion freeride ski

    Get some thick aluminum or stainless, shape it into the corners of the hull opening, and rivet and bond them in.

    image_url-1683-1279031214.jpg

  10. #10
    Top Dog bandit88's Avatar
    Join Date
    May 2014
    Location
    Two Rivers WI
    Age
    29
    Posts
    1,698

    Re: New Project, JS Conversion freeride ski

    Thanks guys,
    That makes sense. How easy do these hulls take on water? Was thinking of cutting out the hood vent and reversing it so it points to the rear. Any other recommendations?
    -95 750SXI
    -86 440 undergoing PJS800 conversion
    -90 TS650

Page 1 of 17 12311 ... LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Powered by vBadvanced CMPS v4.2.0