pxctoday

» Log in

User Name:

Password:

Not a member yet?
Register Now!

» Find OEM Parts

» Jobs

» wallpapers

Page 3 of 3 FirstFirst 123
Results 21 to 25 of 25
  1. #21
    I dream skis Bob Gruen's Avatar
    Join Date
    Jun 2013
    Location
    Atlanta, Ga
    Posts
    502

    Re: Rebuild: 2 550SXs

    The ski is back together and finally running. I sent the head and flywheel off to Newmiller, pics of the flywheel lightening below. Because the yellow zinc coating is machined away it is a good idea to paint the newly exposed steel. I taped it up and sprayed it with automotive primer and an industrial black that I had on hand.

    IMG_20170630_155351298.jpg IMG_20170630_155400919.jpg IMG_20170630_160641733.jpg

    I also had to address the crank pitting. I got the Speedi Sleeves mentioned in another thread and installed two of them, one at each end. They are just a little wider than the two lip seals, so you have to be really careful to place them just right. Not enough room to install two, just have to place the one in the right position. I opted to leave the lip intact. To install it I had to make a deep installation tool out of a PVC pipe and a hose clamp. I also smeared Yamabond into the pitted area of the crank surface and tapped the sleeve into place. Looking back at it, the single lipped seals might actually work better with the Speedi Sleeves

    IMG_20170709_150256281.jpg IMG_20170709_150623393.jpg IMG_20170709_153631624.jpg

    I spent an hour adjusting the low speed screw just to figure out I was very lean (playing around 1 turn from seated while it seems to be around 2). Running a 15.5 impeller in a 550 pump and it seems to be all mid-range and top end. My high school boat had a 440 pump and an Ocean Pro nozzle (I forget the impeller), but it would rev and pull hard off of the bottom end. Am I over-pitched at 15.5? I also advanced the timing a few degrees, as per Newmiller's instructions for the 91 octane milled head. I wonder if i might be better off undoing that...
    Last edited by Bob Gruen; 08-31-2017 at 03:55 PM.

  2. #22
    PWCToday Regular badrocco16v's Avatar
    Join Date
    Oct 2013
    Location
    Detroit Rock City
    Posts
    52

    Re: Rebuild: 2 550SXs

    Cool build!
    '84 JS550 Big Pin 750 twin carb, big pump swap, custom pipe by me
    '85 JS550 bone stock backup/loaner

  3. #23
    I dream skis Bob Gruen's Avatar
    Join Date
    Jun 2013
    Location
    Atlanta, Ga
    Posts
    502

    Re: Rebuild: 2 550SXs

    First ride impressions:

    I have not ridden a pole ski / 550 in 20 years, and I'm used to forcing a Blaster or X2 over on their sides to carve a turn, so getting back into the balance of a pole ski is a bit rough.

    I am not happy with the initial handling. It does not slide out easily and has caught and pitched me a few times at only moderate speeds. I am planning on removing the OEM sponsons / brakes and the bolt on ride plate fins. The initial OEM ride plate and most aftermarket plates have a relief hole right under the steering nozzle pivot, I may drill out a hole there... I may also add a set of Fishsticks. Finally, I would really like to ride a JS hull with Tubbies before I commit to them. I am most interested in getting this boat to be both easy for friends to ride and still enjoyable for me.

    After tuning the ski it does not have enough bottom end; nothing like what I remember my high school ski being. It has plenty of mid-range and top end, so I am planning to return the timing back to stock to bring some torque back to the lower power band. The lack of bottom end is making it harder to power through a turn.
    Last edited by Bob Gruen; 09-07-2017 at 10:56 AM.

  4. #24
    PWCToday Regular
    Join Date
    Aug 2002
    Location
    Seattle
    Age
    42
    Posts
    146

    Re: Rebuild: 2 550SXs

    Hi Bob

    I'm in a similar situation.

    You should not be over pitched with a 15.5. unless you're a big dude - it should pull you out nicely.

    I have the same set up as you sent to newmiller (head, flywheel, halfpipe) - I took first last weekend in region 3 race - ski jumps out of the gate nicely compared to other skis but tends to be missing some top end speed. I still have the stock carb rejetted. The keihin is good for bottom end - the SBN will add some top end. you need to make sure it's dialed properly to keep all your bottom end.

    I think for me the next step is cylinder to newmiller, try a 14/17 to see how it does compared to the 15.5 and SBN 44 to hopefully keep my bottom end and add some top end.

    I've been racing this year with the oem sponsons - they are great in rough water, add stability but agree suck in corner - I'll remove mine. (use to ride in the 90's without them anyway)

    Fishstick are only for extremes turns, you need to put yourself in the water hard, open throttle to feel them. I'm doing fine without them.

    not sure about front sponsons either!!

    Don't forget ..it's a 550 not an SXR 1100 - it's easier to see how you do when you have other 550 on the starting line to compare.

  5. #25
    I dream skis Bob Gruen's Avatar
    Join Date
    Jun 2013
    Location
    Atlanta, Ga
    Posts
    502

    Re: Rebuild: 2 550SXs

    My high school boat had an Ocean Pro piston port block with twin 38s, various pipes, gutted stock water box, and a 440 pump with an Ocean Pro big bore nozzle. It used to tug hard when you pulled the throttle and ran up into the mid 40s. Back then I weighed about 170, now I'm at 185. It is a shame that changing the timing is such a pain in the arse. It doesn't cost anything,... but time.

    Dual 38s worked really well on the piston port 550. If you have a full on race boat I'd suggest dual 38s, but I'm not sure how common dual 38mm manifolds are.

Page 3 of 3 FirstFirst 123

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