Results 1 to 4 of 4
  1. #1

    Join Date
    Mar 2009
    Ballston Lake

    Low end bog problem modded gsx

    I have a 97 GSX 787 with a low end bog problem. I have a FP spec 2 and msd water injection with stock carbs. Grey lines replaced and carbs are rebuilt with filters cleaned. The ski doesnt wanna go past 3500rpms and just bogs down the entire time. Occasionally I can get it past 3500 rmps and it will get up and go but it seems like it only gets goin when the water injection kicks on fully. Also when I switch the fuel selector to off for about 3 seconds the back to on it kicks up to speed again. Once i am passed 3500 it will say running good. Ski still needs some tuning for the setup but this problem has stopped progress. Im gonna pull selector valve this week but figured I would get some opinions. Thanks guys.

  2. #2
    flyin' the friendly skies airbornexp's Avatar
    Join Date
    Aug 2007
    Mahomet, Il. USA
    are you running a hard jetted waterbox? have you talked to Wayne lately?

  3. #3
    One of my skis is very similar, GSX +porting, Novi carbs, etc.

    I've had similar issues on my 787 motors, what I found;
    1. Clogged filter screens inside the carbs, this has happened a few times over the years. Unless you replace EVERYTHING, that goo from the gray lines hangs around for a while
    2. A bad rectifier can cause some of those symptoms
    3. Burned PTO piston, it would rev up but no have enough to get out of the water.

  4. #4
    "Tearing it up on the water" seadoobutch787's Avatar
    Join Date
    Nov 2007
    Dude let me tell ya from experience a spec 2 will eat that rear piston if you don't have those carbs dialed in perfect... Also clean that selector switch real good. On a spec 2 i always run on reserve and nothing else. I run one line from the tank reserve stem to my fuel pump and the return line back to the tank and a vent line that's it. No fuel bowl up front or a selector switch. I took out the chance for an air leak.

    Pull the fuse for the ecwi solenoid and see if your boat runs better.

    Also what hard jetting are you using in that boat. The spec 2 has thread to except mikuni jetting in the ecwi,mid pipe spray bar and if you have a stinger. I would get rid of the water regulator if you still have that on your waterbox and hard jet that with a jet works valve inline to spray at about 4200.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Horrible low end bog, rebuilt carbs, no fuel flapper, few mods...
    By soulraver in forum Yamaha PWC Performance (2-stroke)
    Replies: 15
    Last Post: 07-05-2011, 08:40 PM
  2. 08 GP1300 has bad low end bog
    By 99will273 in forum Yamaha PWC Performance (2-stroke)
    Replies: 11
    Last Post: 07-06-2010, 10:07 PM
  3. Low end bogging
    By VenomRXP in forum Yamaha PWC Performance (2-stroke)
    Replies: 8
    Last Post: 09-28-2009, 09:19 AM
  4. Occasional low end bog??
    By addicted in forum Yamaha Old School Skis
    Replies: 4
    Last Post: 07-21-2008, 04:18 PM
  5. Initial low-end bogging on '06 GPR?
    By Fusion in forum Yamaha PWC Performance (2-stroke)
    Replies: 3
    Last Post: 07-10-2007, 06:52 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