Results 1 to 8 of 8

Thread: GPR Speed Issue

  1. #1
    SMLaker's Avatar
    Join Date
    Sep 2008
    Location
    Virginia
    Posts
    127
    +1
    3

    GPR Speed Issue

    So, I'm using a new SBT 1200PV engine. (Yea...I know SBT yuck). As most of you know I've done a rebuild/rejet on the carbs using OsideBills specs, new reeds, got the d-plate and chip, RIVA FA's, chokes in tact and A-Pump disabled. Since I first bought the ski, the top speed was only 55 at max rpm (near red-line). I am still unable to get past 55 with all the recent mods (GPS confirmed). I assume it's the stock impeller, intake grate and ride plate. Any other suggestions besides measuring the wear ring gap? Tried different trim settings with no real change. Could the sponsons be slowing me down? Engine is running nice and has excellent response with 40:1 Amsoil premix. I weigh in at ~ 180 so it's not me.


  2. #2

    Join Date
    Jan 2006
    Location
    Texas City, Texas
    Posts
    1,249
    +1
    15
    What are your max rpms ? This must be confirmed with an aftermarket tachometer. You really have not done any "speed" mods, so you should see about 62-64..... and that is with good pump components. The rpms will tell you a lot.

  3. +1 by:

    WFO

  4. #3
    Pistonwash's Avatar
    Join Date
    Aug 2005
    Location
    Florida
    Posts
    3,595
    +1
    77
    Read below.

  5. #4
    Pistonwash's Avatar
    Join Date
    Aug 2005
    Location
    Florida
    Posts
    3,595
    +1
    77
    First you must have an accurate tachometer get one of these: http://trailtech.net/tto_tach-hour.html

    Second, you need get an aftermarket impellor like this: http://www.4-tecperformance.com/inde...roducts_id=126

    Thirdly get one of these: http://www.4-tecperformance.com/inde...roducts_id=658

    Fourthly you can get one of these: http://www.4-tecperformance.com/inde...roducts_id=155

    Fifthly: Read up on how to change your angle of rideplate, trim tabs, steeping sponsons and speed secrets. http://www.greenhulk.net/forums/showthread.php?t=16309

    And Lastly...call this guy and follow what he tells you to do and how to get the best out of your ski: http://www.wfoperformance.net/

  6. #5
    SMLaker's Avatar
    Join Date
    Sep 2008
    Location
    Virginia
    Posts
    127
    +1
    3
    [QUOTE=Pistonwash;2189576]First you must have an accurate tachometer get one of these: http://trailtech.net/tto_tach-hour.html

    Second, you need get an aftermarket impellor like this: http://www.4-tecperformance.com/inde...roducts_id=126

    Looking at impellers, Solas recommends the 14/20 Dynafly for modified GPR but Riva recommends the 13/20 setback on their Stage II setup which is what I mostly have already. Read other posts about leading edge/trailing edge and after I verify the RPMs are hitting 7K plus, I think the 13/20 may provide the best of both options, low end hookup and top end speed without overloading. If I had a more powerful engine (heads, pistons) the 14/20 would be better. Thanks.

  7. #6
    Happily Self-Employed WFO's Avatar
    Join Date
    Nov 2005
    Location
    Houston, Texas
    Posts
    12,800
    +1
    449
    A for effort Michael, but you've been away for a while

    Quote Originally Posted by Pistonwash View Post
    First you must have an accurate tachometer get one of these: http://trailtech.net/tto_tach-hour.html

    good cheap tach, but also consider tiny tach, or even better is the pet 2100dx

    Second, you need get an aftermarket impellor like this: http://www.4-tecperformance.com/inde...roducts_id=126

    Solas Concord impeller is best for your craft

    Thirdly get one of these: http://www.4-tecperformance.com/inde...roducts_id=658

    800 grate will work, and is great for top speed, but the R&D or Riva double bar 1200/1300 grate is better for all around

    Fourthly you can get one of these: http://www.4-tecperformance.com/inde...roducts_id=155

    Riva plate is a good plate for speed, but I prefer the R&D plate better for handling and all around performance

    Fifthly: Read up on how to change your angle of rideplate, trim tabs, steeping sponsons and speed secrets. http://www.greenhulk.net/forums/showthread.php?t=16309

    yes, lots of info here on the board for speed from years ago

    And Lastly...call this guy and follow what he tells you to do and how to get the best out of your ski: http://www.wfoperformance.net/
    Thanks Bro!

  8. #7
    Happily Self-Employed WFO's Avatar
    Join Date
    Nov 2005
    Location
    Houston, Texas
    Posts
    12,800
    +1
    449
    [QUOTE=SMLaker;2189980]
    Quote Originally Posted by Pistonwash View Post
    First you must have an accurate tachometer get one of these: http://trailtech.net/tto_tach-hour.html

    Second, you need get an aftermarket impellor like this: http://www.4-tecperformance.com/inde...roducts_id=126

    Looking at impellers, Solas recommends the 14/20 Dynafly for modified GPR but Riva recommends the 13/20 setback on their Stage II setup which is what I mostly have already. Read other posts about leading edge/trailing edge and after I verify the RPMs are hitting 7K plus, I think the 13/20 may provide the best of both options, low end hookup and top end speed without overloading. If I had a more powerful engine (heads, pistons) the 14/20 would be better. Thanks.
    Dynafly was designed for the HO pump, which you dont have

    I would recommend a solas concord 14/20 root impeller, depitched to a 13/19, with the 87mm nozzle

    Also a SBT sleeved motor usually doesnt provide the same power as a non-sleeved motor because of the sleeve/port alignment. Also SBT motors usually have a little lower compression than stock. I really wouldnt go much over stock as far as engine performance mods because of the "quality" of the engine parts. Not saying its bad, but internal parts are not quite the same quality as OEM.

  9. #8
    VeXeD's Avatar
    Join Date
    Oct 2012
    Location
    Port St. Lucie Florida
    Posts
    136
    +1
    13
    Great informative responses all

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. GPR speed issues???
    By unscorpio40 in forum Yamaha PWC Performance (2-stroke)
    Replies: 7
    Last Post: 10-16-2009, 09:52 PM
  2. GPR Nozzle issue
    By PWCManiac in forum Yamaha PWC Performance (2-stroke)
    Replies: 15
    Last Post: 12-28-2006, 05:51 PM
  3. Stock GP/GPR Speeds
    By DrewNJ in forum Yamaha Open Discussion
    Replies: 7
    Last Post: 09-19-2006, 09:38 PM
  4. stock 04 gpr speed?
    By great lakes gpr 1200 in forum Yamaha PWC Performance (2-stroke)
    Replies: 7
    Last Post: 07-15-2006, 08:44 PM
  5. ALL THIS SMACKING ABOUT GPR SPEEDS!!
    By liquidflare in forum Yamaha PWC Performance (2-stroke)
    Replies: 15
    Last Post: 01-08-2006, 10:15 PM

Posting Permissions

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