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  1. #1

    Oil mix after a top end rebuild on Kaw 1100 Stx di ENGINE 2 stroke

    I am replacing the pistons on a Kaw 1100 STX di 2002 JETSKI with Pro-X pistons.

    WOuld you recommend mixing more oil into the gas during the breakin period 10 hours?


  2. #2
    Mixing oil in the gas on a DI engine will do very little for the pistons because the fuel doesnt inject until the piston is nearly at TDC and then is instantly ignited. I have heard both ways, some people say never mix oil with the gas on a DI, claim it will do damage. Others say to mix a little in to keep the fuel pump lubricated with todays alcohol fuels. When I rebuilt mine a couple of years ago I lubed the cylinders on assembly, mixed the fuel at 100-1 and when I fired the engine I held the oil pump wide open.

    As you probably already know, dont run a DI for very long without water or it will damage the EMM.

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    TexasZ's Avatar
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    Quote Originally Posted by pierstar View Post
    I am replacing the pistons on a Kaw 1100 STX di 2002 JETSKI with Pro-X pistons.

    WOuld you recommend mixing more oil into the gas during the breakin period 10 hours?
    50 to 1 the first tank. After that 1 ounce per gallon for the lenght of time desired.
    Definitely do as Comp recommended...lube parts when assembling.

    Make sure all your cooling lines are clear, especially the one up front covering the stator, it clogs easily and as Comp noted it will fry the EMM if not cooled adequately.

    My wife has a 2000 model STX-DI we bought for her new...we call it the perfect ski.

    Edited to add: see post 7
    Last edited by TexasZ; 11-17-2012 at 05:30 PM.

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    I would stay away from premixing any DI motor. Really doesnt do anything to help.

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    Quote Originally Posted by BryanP View Post
    I would stay away from premixing any DI motor. Really doesnt do anything to help.
    I respectfully disagree. I agree that it isn't needed after first tank or even half a tank, but it is done at first after the oil injection lines have been taken loose or replaced to make sure the motor is oiling, until oil is pumped all the way through the lines and the air bubbles in the lines have worked themselves through.

    Applies moreso to carbed engines than injected, but why take chances. Kawasaki themselves stated that we run the 50 to 1 mix for the first tank when we bought my wife's 2000 stx-di.

    I don't know about other skis but this is standard procedure on Kawi's and Yamaha's after replacing oil lines or where they have been taken loose for other repairs.

    Edited to add: see post 7
    Last edited by TexasZ; 11-17-2012 at 05:31 PM.

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    The point on the DI motors is that the premixed oil never reaches the bottom end of the motor. On a carbed motor, absolutely run premix after working on the oil injection system, although its rather simple to get the lines all filled and primed anyways. On a carbed motor, that premixed fuel enters through the bottom end, past the crank and up into the cylinders, leaving the oil everywhere in the motor. On a DI motor, you are just shooting the oil into the cylinder after the exhaust port is closed, and burning it off right away. Why take the chance of fouling those expensive plugs? But if it works for you, then do it. I know on the Polaris Ficht injected motors, that adding the oil to the gas can actually cause problems. They state not to add any oil for break in. I believe Kawi uses the same DI system.

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    TexasZ's Avatar
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    Quote Originally Posted by BryanP View Post
    The point on the DI motors is that the premixed oil never reaches the bottom end of the motor. On a carbed motor, absolutely run premix after working on the oil injection system, although its rather simple to get the lines all filled and primed anyways. On a carbed motor, that premixed fuel enters through the bottom end, past the crank and up into the cylinders, leaving the oil everywhere in the motor. On a DI motor, you are just shooting the oil into the cylinder after the exhaust port is closed, and burning it off right away. Why take the chance of fouling those expensive plugs? But if it works for you, then do it. I know on the Polaris Ficht injected motors, that adding the oil to the gas can actually cause problems. They state not to add any oil for break in. I believe Kawi uses the same DI system.
    "The point on the DI motors is that the premixed oil never reaches the bottom end of the motor."

    Point taken, you're absolutely right, thanks for taking the time to educate me, I appreciate it. Comp mentioned the same thing but somehow it went right over my head. I was mostly going by what the Kawasaki dealer and mechanic told me 12 years ago when we bought my wife's DI. That was the first year Kawasaki put them out so I would imagine they have learned a few things since too.

    See, you can teach old dogs new tricks.

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    I love the concept of the DI motors. I still think the manufacturers could build these, meet emission standards, and produce an affordable priced new machine. If outboards are still DI 2 strokes, why can't they still build watercraft like this?

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    Quote Originally Posted by BryanP View Post
    I love the concept of the DI motors. I still think the manufacturers could build these, meet emission standards, and produce an affordable priced new machine. If outboards are still DI 2 strokes, why can't they still build watercraft like this?
    I like the concept too and 'so far' we have had zero problems with my wife's 2000 model DI. It "earned" the nickname "the perfect ski" from us cuz' that's what it has been, perfect in every way and the handling is awesome.

    I'm sure you have heard the numerous never ending barrage of folks saying negative things, even POS most times, towards the DI because of the EMM problems...but as the meangreenman and other longtime Kawi mechanics have said, what takes out the EMM is overheating from a clogged cooling line. The most susceptible part of the Kawi cooling system is the stator cover on the front of the engine. We make dang sure that is clean along with the rest of the cooling system and we have had zero problems for 12 years now.

    A bad reputation whether deserved or not will cause a manufacturer to discontinue making a product. The oncoming of the 4 stroke is probably what had most to do with the discontinuation of production for the Kawi DI. Myself personally, I still love the 2 strokes and the injected ones leave very little if anything to be desired.

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    Agreed. I know the Polaris machines had some issues with EMM failures as well. Cooling seemed to be the culprit. DFI repairs these EMMs and makes them better than new when they are finished. The next ski I buy will most likely be direct injected. They are relatively simple to diagnose, and just push the button and go is a nice thing. They are not the best for people who want to modify their machines though.

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