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  1. #1

    Exclamation Slt 780 HELP!!!!PLEASE

    Hi, my name's Dustin I am pretty much at a wit's end with my Polaris SLT 780. It has the Blue Fuji motor when I first got it it had carb problems and low compression but got it to run good Labor Day 2 Days Later started running rough and shut off made it to the boat ramp got it out of the water got it home and pulled the heads. The mag cylinder was of course melted so I figure no big deal pulled all three jugs took to the Machine Shop they bored them out .75 over with brand new Pistons Rings wrist pain wrist pin bearing the whole nine yards. Came home put it all back together. Test ran it for a minute or two with the garden hose hooked to it seemed very responsive so I put it in the water made it from the boat ramp to my dock which is only about 600 yards and started running rough so immediately shut down and felt all three jugs mag cylinder was scorching hot. Pulled ahead on the mag cylinder and once again melted a hole. So ordered new jug took two machine shop and had them punch it out to match the other two now this time I had the whole motor pulled so I dropped the pan changed all the crank seals deleted the oil pump which I was running premix anyway but they just cut the rod so I Permatex that put all new base gaskets head gaskets all 9 of the reed valve gaskets took out the thermostat did a leak down test on the Block it only lost 9 pounds of vacuum in 35 minutes put Magneto/ stator right back in the case split mark rebuilt all three carbs with genuine Mikuni kits with needle and seat the pop off pressure on them 2 were 21 and the mag was about 22 put it all back together and in this ski it fired right up ran for about 10 seconds and started revving High I can hold my finger half over the mag carb and it would idle down and spit gas on my finger's like normal when you choke something but after about a minute with garden hose wide open no thermostat the mag cylinder started getting extremely hot compared to the other two I shut it down pulled the head and Luckily everything still looks good has plenty of oil in cylinder so I don't know if this is a lean condition but that's what it's seeming like but at the same time not making sense please somebody help

  2. #2
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Cut what rod?

    Have you inspected the top water manifold (water bar) for clogs?

    The water flow feeding each cylinder is separate from the exhaust manifold (going from memory for the Fuji 780 engine). Make sure the transfer holes and gasket are not blocking flow.

    Are you sure the head gasket for the MAG cylinder is not installed upside down or rotated out of position? The gasket has holes for the water flow.

  3. #3
    The rod for the oil pump I just took the whole gear out when I took the pan off and the head gaskets are pointing up with the 78 as it should be with the little ear under the water inlet of the water rail

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