Page 1 of 2 1 2 LastLast
Results 1 to 10 of 12
  1. #1

    Join Date
    Sep 2008
    Location
    Clarksburg, WV
    Posts
    609
    +1
    1

    97 GP Jetworks Mod Question

    Looking to do the Jetworks mod as I have a very long no wake zone at the launch ramp at 2 of the 3 lakes that I frequent.

    The 97 pipes are different than the 98-99. They have smaller fittings although I am not sure what size. Looks around 1/4" althought I know yamis are metric hose sizes.

    I am wanting to run the 3/8" Jetworks Valve.

    Should I:
    Get a new pipe (98-99 pipe)?
    Cut the old fitting off, drill and tap for the new bigger fitting?
    Just get a 1/4" Jetworks valve?

    I have seen some talk of this but nothing of what people actually ended up doing.

    Planning to T off of the rear cylinder


  2. #2

    Join Date
    Sep 2008
    Location
    Clarksburg, WV
    Posts
    609
    +1
    1
    Why drill and tap a new hole if there was already one in the nozzle?
    Click image for larger version. 

Name:	GP Jet Works mod1.jpg 
Views:	64 
Size:	53.8 KB 
ID:	176451

    Click image for larger version. 

Name:	GP Jet Works mod2.jpg 
Views:	116 
Size:	119.5 KB 
ID:	176452

    What does the valve on the water bypass do?
    Click image for larger version. 

Name:	GP Water Bypass with valve.jpg 
Views:	88 
Size:	114.0 KB 
ID:	176453

  3. #3
    Moderator OsideBill's Avatar
    Join Date
    Mar 2006
    Location
    United States
    Posts
    11,875
    +1
    30
    The center outlet on the head is an aftermarket mod if too much water is dumped the center cylinder gets too cold so the valve restricts the water to balance the temps.
    I have attached an old water routing diagram Pistonwash did years ago.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	GP1200%20dual%20cooling%20h2o%20diagram.jpg 
Views:	602 
Size:	19.9 KB 
ID:	176508   Click image for larger version. 

Name:	GP1200%20stock%20cooling%20h2o%20diagram.jpg 
Views:	309 
Size:	16.0 KB 
ID:	176509  

  4. #4

    Join Date
    Sep 2008
    Location
    Clarksburg, WV
    Posts
    609
    +1
    1
    Quote Originally Posted by OsideBill View Post
    The center outlet on the head is an aftermarket mod if too much water is dumped the center cylinder gets too cold so the valve restricts the water to balance the temps.
    I have attached an old water routing diagram Pistonwash did years ago.

    Bill, in the second picture, where does the stock inlet hose from the transom mount to?

    Also, on the 97s, where the Jetworks goes into the pipe it is only 1/4". So would I need a 1/4" to 3/8" T fitting and get a 1/4" JW Valve? Or cut the nipple off on my pipe and drill and tap for a 3/8" fitting?

  5. #5
    Moderator OsideBill's Avatar
    Join Date
    Mar 2006
    Location
    United States
    Posts
    11,875
    +1
    30
    Quote Originally Posted by akjose View Post
    Bill, in the second picture, where does the stock inlet hose from the transom mount to? In the original factory location bottom of the exhaust manifold

    Also, on the 97s, where the Jetworks goes into the pipe it is only 1/4". So would I need a 1/4" to 3/8" T fitting and get a 1/4" JW Valve? Or cut the nipple off on my pipe and drill and tap for a 3/8" fitting?
    Not sure on this one, I know the later model pipe has benefits over the early one as far as the stinger is concerned. I would try and find a later model pipe if it was mine. Also the 1100 exhaust manifold gasket has better water routing then the 1200 did, and is a mod we all used.

  6. #6

    Join Date
    Sep 2008
    Location
    Clarksburg, WV
    Posts
    609
    +1
    1
    Quote Originally Posted by OsideBill View Post
    Not sure on this one, I know the later model pipe has benefits over the early one as far as the stinger is concerned. I would try and find a later model pipe if it was mine. Also the 1100 exhaust manifold gasket has better water routing then the 1200 did, and is a mod we all used.
    Did not know about the manifold gasket.

    Back to your post about the shut-off valve on the hose. The PO had one on the front pipe. Is there any benefit from the front cylinder or does it need be on the second cylinder routing?

    I have a Riva O-ring head installed, but have also acquired a Group K milled head, Should I switch to the milled head or are they both basically the same?

  7. #7
    Moderator OsideBill's Avatar
    Join Date
    Mar 2006
    Location
    United States
    Posts
    11,875
    +1
    30
    Quote Originally Posted by akjose View Post
    Did not know about the manifold gasket.

    Back to your post about the shut-off valve on the hose. The PO had one on the front pipe. Is there any benefit from the front cylinder or does it need be on the second cylinder routing?

    I have a Riva O-ring head installed, but have also acquired a Group K milled head, Should I switch to the milled head or are they both basically the same?
    Not sure what you mean by PO, but on a stock water routing set-up with the center cylinder tapped for water outlet I used the restrictor valve on center only.

    As far as heads go it all depends on the compression you are looking for, do you knwo the difference between the two CC wise?

  8. #8

    Join Date
    Sep 2008
    Location
    Clarksburg, WV
    Posts
    609
    +1
    1
    PO = Previous Owner

    The Group K cut was advertised as 150 psi compression. The Riva head has 42 cc domes /stock bore.

  9. #9
    Moderator OsideBill's Avatar
    Join Date
    Mar 2006
    Location
    United States
    Posts
    11,875
    +1
    30
    The picture in the previous post shows it coming off the center cylinder. 150 PSI is what you are after looks like either one will do that.

  10. #10

    Join Date
    Sep 2008
    Location
    Clarksburg, WV
    Posts
    609
    +1
    1
    Sorry, those arent my pics. I got those from someone on the hydrotoys website.

    Mine was coming off the front cylinder, but I pulled it because it was ghetto-rigged-looking. Just discovered yesterday too that my bypass fitting (plastic bilge fitting) was broke at the nipple. Dont know if it happened last season or just happened when I was messing around inside the hull.

    I didnt know if there was a benefit of the O-ring style from the gasket style head.

Page 1 of 2 1 2 LastLast

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Jetworks Mod Question
    By DoomTrain in forum Yamaha PWC Performance (2-stroke)
    Replies: 4
    Last Post: 05-05-2011, 12:22 PM
  2. Holeshot/Jetworks MOD Question
    By fatrat in forum Yamaha PWC Performance (2-stroke)
    Replies: 4
    Last Post: 08-11-2010, 08:43 PM
  3. Jetworks Mod Question ????
    By james k in forum Yamaha PWC Performance (2-stroke)
    Replies: 7
    Last Post: 10-16-2007, 11:21 PM
  4. Jetworks Mod Question ???
    By Rusty in forum Yamaha PWC Performance (2-stroke)
    Replies: 7
    Last Post: 07-05-2006, 11:57 PM
  5. Jetworks Mod Question
    By Gipper in forum Yamaha PWC Performance (2-stroke)
    Replies: 5
    Last Post: 02-09-2006, 02:30 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
  •