Results 1 to 4 of 4
  1. #1
    bowsniper's Avatar
    Join Date
    Aug 2008
    Location
    macomb,michigan
    Posts
    5,896
    +1
    6

    Bored Nozzle and Thrust question

    when you open up the exit nozzle to 87mm, what actually happens? I understand it allows more water to get out the rear, hense more push or thrust part,, but what did this mean? was there "leftover" water in the pump,prop,intake , or before "areas" that couldn't be processed and now that "extra" water can be?

    If thats true, then all the skis should have it done.

    will it scrub or help top end? I'm guessing it would help the holeshot at least if your getting more thrust out the back.

    does the steering nozzle need boring too? I heard the ski acts funny if you dont do that one also. is that true?

    how does boring the nozzle affect the 5-vane,6-vane-8-vane stators? do you need to change a prop too? since your movng more water thru the pump, i would think so. you would need a different pitch to accomadate the higher volume?
    Last edited by bowsniper; 03-09-2011 at 11:56 AM.


  2. #2
    Race, wreck, repeat delagem's Avatar
    Join Date
    Aug 2006
    Location
    Homer, NY
    Posts
    728
    +1
    2
    Boring a nozzle will most definitely decrease top speed. It will, to a point, enhance bottom end.

    I swapped the grate on my Jetmate from 90mm (!) down to a 76mm, and gained 2.4mph on top.

    There were some posts on making sure your steering nozzle was (I think) 2 mm or more larger than your pump nozzle.

    Call Dave at Impros and bounce your questions off of him. I talked with him for half an hour on my Jetmate project.

    Side note: I have always disagreed with this need for "Low end grunt" on a PWC. How often do you ride at 1/4 throttle? I watch my tach, and I'm up over 6,000 rpm in less than maybe 2 seconds. Exactly how much help is this low end doing during that time? Unless you're setting up to backflip waves in the surf, and don't have 3 seconds to get up to speed, I think this idea of low end is a misnomer.

  3. #3
    I like Boobs. wetwolf's Avatar
    Join Date
    Nov 2005
    Location
    The NSA know's that I'm in Spokane, WA
    Posts
    805
    +1
    106
    Boring the nozzle will give you more low end and midrange since you are increasing the VOLUME of water going oout the back of the pump.You will generally lose top end though because with the larger nozzle, you don't have as much VELOCITY now. You can bore the nozzle out to 87mm and install an Adjust-A-Thrust. With this setup you get the low end and midrange of the large nozzle, but the top end of the small nozzle. The steering nozzle needs to be 2-3mm larger than the exit nozzle.

  4. #4
    bowsniper's Avatar
    Join Date
    Aug 2008
    Location
    macomb,michigan
    Posts
    5,896
    +1
    6
    Thanks. I'm planning on getting a ATT. I'll let ya know.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Steering nozzle and grate questions.
    By txredxj in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 07-22-2015, 08:00 AM
  2. Vxr exit nozzles, steering nozzle, and other questions
    By bryantjopplin in forum Yamaha PWC Performance (4-stroke)
    Replies: 101
    Last Post: 02-17-2014, 01:36 PM
  3. general question about bore size and performance
    By tshank123 in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 07-11-2012, 06:43 PM
  4. Questions about Riva adjustable nozzle and Riva rideplate for FZ
    By Kelly_A in forum Yamaha PWC Performance (4-stroke)
    Replies: 34
    Last Post: 10-24-2011, 05:31 PM
  5. Bored Nozzle question.
    By bowsniper in forum Polaris Open Discussion
    Replies: 11
    Last Post: 12-19-2009, 09:54 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •