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  1. #1

    Join Date
    Mar 2009
    Newark, DE

    '96 GTX (787 engine) bogs when throttle applied (fresh engine AND carbs!)

    Fresh 787 build. I fired it up for the first time and it ran great for ~3minutes or so (attached to hose, of course) and I was very happy with the results. I let it cool down for about 2hrs and went to start it again. Initially, it ran great (again), but then it started bogging down. I figured maybe the plugs were fouled from the extra oil (SBT break-in oil) in the gas tank. But, they looked fine. Now, every time I go to start it, it runs perfect for anywhere between 10 seconds and a full minute before it starts running poorly and won't respond to the throttle. The fuel system is all new (carbs, lines, etc.) Thoughts?

    When I went to try to start it a day later, the plugs were soaking wet with fuel, so I hit the starter with the plugs out and an obnoxious amount of fuel came out of the plug holes! Suspecting a bad needle/seat, I rebuilt the carbs 100% with NEW Mikuni parts, including new needle and seat. Fulcrum arms are level. ~32psi pop-off pressure in both carbs.

    FYI, ski is 100% stock.

    Everything I can think of checks out. I just started it in my driveway and I'm having the same symptoms. It'll start up just fine, but won't respond to kinda bogs down when you try to give it gas. I'm at my wits end with this. Where should I troubleshoot next???

  2. #2
    first off you never or I never break in an engine on the hose as it runs the water backwards to backflush your cooling system instead of preheating the water first when it runs in normal direction.I think your problem is either the petcock is partially plugged(on off fuel switch)Did you replace the fuel lines as they come apart inside and plug carbs,the little filter in carbs etc.Second if you had lots of fuel in cylinders,the needles were not seating,Check vacuum line,check fuel line between carbs,In other words if you didnt change out your fuel lines when you rebuilt carbs and engine,The carb filters are probably plugged again.take off the return line from carbs ,see if it pumps fuel out of carbs while cranking,if not start checking the petcock,the fuel pick up etc.also be sure you didnt cross your fuel line with your return line.hope this helps>Marvin

  3. #3

    Join Date
    Mar 2009
    Newark, DE
    I wasn't trying to break in the while on the hose. I just had it running for a couple of minutes that first time to make sure it was ready to take it to the water for a second test and start the break in procedure.

    The entire fuel system is new...nothing is clogged.

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