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  1. #1

    98 GSXL tops out at 6300 RPMs ...on a good day

    I posted this on PWCtoday and got some good advice but thought I'd ask here too.

    I have 7 hours on a 1mm overbore remanufactured 951 engine in my 98 GSXL.

    I installed OEM carb rebuild kits and a jet kit (85 LS, 167.5 HS, 2.3 N/S) with proks. 1.5 turns out on the LS screws and 0 turns on the HS screws. Idles at 1450 in the water. I am using the accellerator pump and the stock oil injection. Replaced all the grey gas lines and cleaned the fuel selector. New prop and good wear ring. The new prop is an SBT but from a 97.5 gsxl. The oem number is 271000654. It's a different pitch than the 271000905 stock 98 gsxl prop I replaced. I'm told I could lose some rpms because of the different prop.

    It runs good but I have never been able to get over 6300 RPM. I cut the raves myself. The engine rpm jumps from 4500 to 5100 in the blink of an eye. It's a b-i-g power rush. I'm assuming this is my raves working properly.

    The engine goes from 5100 to 6100 fairly quick but it takes a while for it to reach 6300. Sometimes it won't even reach 6300.

    I've tested the water regulator by pulling the hose off the exhaust, riding and watching for the water volume to decrease as the rpms increase. The volume never decreases. I've also ridden the ski with the hose off (for a couple quick runs) but I still couldn't get it to go over 6100-6200 rpms. Shouldn't the engine reach top rpms with the hose disconnected from the pipe? And if it doesn't... does that mean my problem isn't the WR?

    I've also snipped 1/2" off the WR spring and turned the red cap all the way out. Neither made any difference on the water volume coming out of the WR hose at any rpm.

    If the prop comes out of the water on a wave the engine will go to 6800-6900 rpms.

    After installing the new engine... I had a bear of a time getting the 2 pipe sections together and the big clamp on. I took the pipe apart today to make sure it was together correctly. It seemed like it was a little off... not seated perfectly. I put it back together and got the clamp on but am still not 100% sure I have a tight fit here. The clamp fits fine and tightens up fine. I'm not sure if the joint can even be out of line if the clamp is on. There's really only one way the clamp will go on and tighten. Either it's on right or it's not on and won't even come close to tightening.

    If that exhaust connection isn't perfectly tight could that cause my rpm loss? If it wasn't seated right, would it be obvious? I've ran my hand around the connection while it's running and can't feel an exhaust leak.

    What else can I look for?
    Last edited by d0n; 08-09-2008 at 04:11 PM.


  2. #2
    96XPSS's Avatar
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    The pipe should be connected with red RTV. It will kill max rpms if not seated properly, and you can easily not get it right and the clamp will tighten up like you do have it right. Remove the clamp and visually confirm the flanges are aligned.

    You also didn't mention wherther you cleaned the internal filter screen in each carb when you rebuilt them?

    Another culprit to check, bad water regulating valve. It will dump too much water into the pipe killing max rpms.

  3. #3
    steach's Avatar
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    Quote Originally Posted by 96XPSS View Post
    You also didn't mention wherther you cleaned the internal filter screen in each carb when you rebuilt them?
    +1 ...If you didn't clean out the tank it's good for one more filter glogging.

  4. #4
    Quote Originally Posted by steach View Post
    +1 ...If you didn't clean out the tank it's good for one more filter glogging.
    The oem rebuild kits have new internal filters in them so yes, they were changed. Also, changed all the grey fuel lines.

    I didn't drain and clean the tank. I did drain 98% of the old gas. There are 2 screens (1 in the fuel baffle & 1 in the fuel seperator) that should pick up any left over crap long before it gets to my carbs internal filters.

    I don't think the problem has anything to do with the fuel system.

    It's probably the pipe connection. I've heard that the 2 piece exhaust on the GSXL can be put together outside the hull and then installed in one piece. Is this true?

    I tried it when installing the new engine but could not get the exhaust to go in in one piece. I had to put the head pipe on and then put the lower pipe on. Doing it this way makes it really hard to get the 2 pipes to seal correctly.
    Last edited by d0n; 08-09-2008 at 09:39 PM.

  5. #5
    steach's Avatar
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    Quote Originally Posted by d0n View Post
    There are 2 screens (1 in the fuel baffle & 1 in the fuel seperator) that should pick up any left over crap long before it gets to my carbs internal filters.
    You would think so...Check again.

    It's probably the pipe connection. I've heard that the 2 piece exhaust on the GSXL can be put together outside the hull and then installed in one piece. Is this true?
    The key to the 951 exhaust is the pipe to manifold bond. After assembling the pipe halves as RQ said. Redo this bond. (this is why SD came up with the rubber diaper)

    -clean the surfaces of the manifold and pipe and use a new gasket.
    -install pipe bolts/nut, and braket bolts loosely. (w/blue LT)
    -snug the mount bolts up lightly.
    -torque the pipe bolts/nut to 20#.
    -loosen the rear pipe mount bolts and re-torque them to 20#
    -now torque the center mount bolts to 20#.

    -torque the pipe bolts/nut to 30# (for the nut get the SD tool 529035505)
    -torque the center mount bolts to 30#
    -torque the rear mount bolts to 30#
    -snug the coupler clamps.
    Last edited by steach; 08-09-2008 at 11:48 PM.

  6. #6
    Thanks!

    the pipe to manifold connection was easy. I did use a new gasket. No problems there.

    The connection I'm worried about is the upper pipe to lower pipe. I can get it together perfectly with the entire pipe out of the ski. BUt then I can't get the 1 piece pipe in.

    If I put the 2 pipe piece in the ski seperately, I can't really get the 2 pieces to seal right.

    Has anyone had any luck installing the pipe in one piece, in a GSXL?

  7. #7
    96XPSS's Avatar
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    I don't think it can be done externally, because there is no way to you can get the angle perfect to match the bolt holes to mount it.

    If you get the lower chamber supported properly the clamp should hold it snug enough to allow slight turning to align it. All this has to be done with freshly applied red RTV...so you have a time limit.

    Use an inspection mirror and a flashlight to shine in the open slots of the clamp to verify it's aligned all the way around. It's a pain, but can be done.

  8. #8
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    I just read in your other thread that the RAVE's rd cap screws are all the way DOWN????? Then they are nto opening all the way...

    Take the black caps off, and the spring, go out for a run. Ski will be sluggish out of the hole, but thats nothing. Go for a blast at WOT, see what RPM's you get....IF you get right to 6900's, around 7000, then your prop is pitched right...

    Put the caps back on, make the red screw flush...Go back out, WOT should be right at what it was with no caps.....Adjust at 1/2 turn increments until R's fall off at WOT....

    Once they do, go back 1 or 2 clicks, and you are set...


    This is what I did after I rebuilt the motor on mine, and when I was dialing in a new prop...

  9. #9
    great advice. I will try that next time I'm out.

  10. #10
    785xp's Avatar
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    Did you check the RAVE on the waterbox. They come with the clamp from the factory pointed up at the rubber bellows and over time, this creates a small hole. When you install the new bellows and clamp, use some pliers to bend the points downward away from the bellows.

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