96 xp water routing?
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  1. #1
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    96 xp water routing?

    hey bill iam a little confused..Iam putting a new pipe on a 96xp i recently purchased. I'am not sure which water line is the inlet. Right now, the waterline comes from the white fitting that extends out of the hull to the water spigot then into the head of the left hand side if you are standing behind it. On the opposite side of the head , the right side, which I always thought was the water exit runs directly into the pump. Im confused on which is the water inlet. The shop Manuel looks like the inlet comes from the pump and not that white little fitting outside the hull? Is this currently set up backwards? However, the fpp spec2 diagram has the routing exiting the right side of the head and going to the pump, kind of vague drawing though.Is The water inlet come from the pump? or does that create some sort of vacuum that allows that white little fitting outside the hull in front of the pump housing the inlet. thanks

  2. #2
    PWCToday.com Is My Home Away From Home Mr. Bill's Avatar
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    Re: 96 xp water routing?

    Your inlet water on any PWC comes from higher water pressures that are created when the impellor sends a blast of water into the "venturi nozzel" where it is compressed and speeded up to form a large blast of water called "thrust" to pass through the steering nozzel and make the boat move forward.. A by product of compressing water, is high water pressures for all of the water that has passed the impellor and travels through the vane section to straighten out the water flowing into the venturi nozzel, and after that, through the steering nozzel, and come shooting out of the nozzels at a very rapid speed.
    In the vane section of the jetpump, they drill a few small holes at the top of the vane section and up into another chamber on top of the pump. That chamber ends and has a 12mm threaded hole, to which a long black 12 mm threaded tube screws into. The tube goes forward and through the transom. A black 12mm i.d. rubber water hose is attached to the black tube on the transom end of the hull, right above the fiberglass inner liner that houses the jetpump water inlet tunnel that is under the rear of the hull bottom. The water inlet tract has a water scoop grate over the inlet tract to pickup water from the lake and force it up through the tunnel and into the impellor section of the jetpump where that water is processed as mentioned above to do two things, provide high pressure water for thrust, and high pressure water to cool the engine and exhaust system.

    From the 12mm black fitting, the water is carried by the 12mm black hose and is connected to the left side of the head. Under the head cover plate, is a water channel that leads the water around the top of both clyinder head combustion chambers to remove the heat that is built up during the ingition of the fuel above the piston, and pull heat out of the sparkplug metal base housing that holds the white porclean parts of the sparkplug. After the water travels through and comes out the fitting at the front of the head, another shorter black hose carries the water from the head and into the exhaust pipe water jacket fitting down low at the front of the headpipe. The water travels up the exhaust pipe water jackets and goes into the exhaust manifold water jackets on the side of the motor. From there, the water exits the manifold into water ports just under each exhaust port on the clyinder, then through the clyinder water jackets up and out of the right side of the head where there is another water fitting and a 12mm black hose that carries the hot water to the back of the boat and eventually back into the lake. The early models of Sea Doo's dump the water into the exhaust fitting that is at the rear of the hull where exhaust gasses and engine water are mixed together to lower the tone of the exhaust noise that the watercraft sends out of the boat.
    On all 1997 and later models EXCEPT the SPX ( which is a newer version of the 1996 XP ), the water is carried to a fitting on the pump support plate. Those are the models that have the flush tube next to the jetpump that allows you to merely screw any garden hose into the tube to backflush the cooling system to remove salt and meneral deposits that otherwise would be sitting in the exhaust pipe and engine rotting away at the aluminum.

    When you see a 787 motor that those 12mm hoses are put onto the opposite fittings on the back of the head, you are looking at a motor with "reverse water cooling" that allows the high pressure cooling water to travel in the opposie direction that Sea Doo intended it to go. That is done either on purpose or by mistake, as by crisscrossing the two 12mm black hoses and attaching the to the opposite sides of the head is so easy to do, that sometimes it is just a mistake.
    There are those who believe that by allowing the cooling water to pass through the engine backwards, it sends a higher tempeture preheated water to the headpipe of the exhaust system. Somehow they think that is better than the other way around. The flaw in that thought is that you want the clyinders to heat up sooner, rather than later, to prevent cold piston sizeures, a common reason for a mild siezure when idiots do not properly warm up an engine before floorboarding it. You want the clyinder sleeves to expand away from the pistons before you pour the coal to the pistons and rapidly expand them while still running up and down in a cold sleeve that has not had time to expand. Aluminum pistons expand at a rate of about three times that of cast iron steel. So, if the motor is too cold and you run it hard at high rpm, the pistons will outgrow the sleeves and you will have no piston to clyinder wall sleeve clearances and no way to let oil lubricate the pistons and sleeves. The next thing in line is boring and honing the sleeves out for new pistons, and the expense you caused yourself to spend to do it.

    What any venturi does, is compress whatever is forced through it.

    The upper center of your carbureators has a venturi. As air flows into the top of the carb, it passes through the portion that is the venturi. That takes the incoming air and multiplies the speed and pressure of the air as it exits the venturi, which in turn, speeds the airflowing into the engine, raising case pressures that are necessary to push a mixture of gas and oil up through the transfer ports and above the piston top with each revolution of the crankshaft so it can be further compressed and ignited

    On a Rotax motor with two fittings at the back of the head, the fitting on the left side of the head is always the inlet water fitting coming from the largest of the three fittings that are at the top of the jetpump tunnel. This is if you are viewing the motor from behind the engine. Left is inlet, right is outlet.

    Sea Doo pumps always have two bailer fitting at the very top of the jetpump and one larger fitting on the righthand side. The larger fitting is cooling water, the two smaller fittings are what vacumes water out of the bilge scuppers at the lowest portion of the innerhull.
    Last edited by Mr. Bill; 03-11-2010 at 06:04 PM.

  3. #3
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    Re: 96 xp water routing?

    thank you,starting to make sense now. If I have a spec 2,180psi heads, 46 novis, flame arestors, r and d intake manifold would reverse water cooling have any advantages compared to the normal cooling system? Other than just the negative of not being able to cool the heads first?

  4. #4
    PWCToday.com Is My Home Away From Home Mr. Bill's Avatar
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    Re: 96 xp water routing?

    Not that I know of on a 787 motor. Just switch the two lines at the back of the head. I do not think you would notice any differences in power, but doing whatever you can to cool the combustion chambers can help keep the detonation within a safe zone if the carb jetting and the ignition's timing and timing curve is all set properly.

    When modifying a motor and adding something as different as the Spec2 to it, it is prudent to follow the directions in the ignition section of the oem service manual that tells you how to properly check the timing to see if it is set properly using a timing light. In lieu of buying the oem pointer that bolts to the rear engine mount for your reference point, you can fabricate a pointer using a stiff wire wrapped around the mount bolt and bent to extend over the PTO flywheel as close to the flywheel as you can get it somewhere up at the top of the PTO flywheel where you can point the timing light directly down over the wire, not on an angle. This will give you the most precised idea of where it is actually set. You will also need a dial indicator in the sparkplug hole.
    The manual should state the rpm that you must run the motor at when checking timing. I believe it is 3500 rpm, but check the manual to be certian that my memory of it is correct.
    The reason they choose that rpm to test it at, is there is an rpm that allows for a 500 rpm cushion, before the timing changes per what the timing curve in the ignition dictates that at 4000 rpm or more, the timing ( in degrees ) will climb to the next preset number of degrees.
    The timing curve for a motor in degrees will be extremely low a very low rpm, like when the rpm is being dictated by the starter motor which is probably no more rpm than about 300 rpm. Add a few more rpm of the motor as it first starts, the curve jumps way up and advances so the engine can accellerate away form cranking rpm. It will continue to advance up through higher rpm ranges until it reaches a point well past 6000 rpm and then start slowly retarding. At full rpm it will quit retarding down in the 16-17 degrees range.

    With a Spec2 and 180 psi, you cannot run this motor on premimum pump gasoline. You would need an octane rating of around 96-98 minimum octane. So, unless you reduce the compression ratio, your motor will detonate beyond the allowable limits ( measured in percentages of the amount of detonation that can occure without inflicting damage to the motor ).

    As the only way to alter an oem iginitions timing curve, you would need to get your hands on a Sea Doo Racing Programmer, not the regular Programmer used at dealership, as they cannot change the curve that is preset into an oem ignition, nor can they change the maximum rpm of the rev limiter.

    With a well tuned motor using a Spec2 exhaust system, even on high octane racing fuel, 16 degrees may be too much advance for your compression when turning the motor well past 7050 rpm, where the oem curve ( 16-17 degrees advance ) expects the motor to be well past what a 787 will actually turn using a stock 787 tuned pipe exhaust system.

    My advice to you, if you want to use premimum pump gasoline, is to reinstall a stock oem head and make sure the squish clearance is at the maximum tolerance as stated in the 787 service manual for the year model MPEM and CDI that are in your grey electrical box, unless it is a 1997XP, where everything is stored in the MPEM module at the front of the hull.

    There is an alternative though, other than a hard to find Racing Programmer for changing timing curves and rev limits. You can add either an MSD Enhancer in place of the oem CDI, or you can install a less expensive Micro Touch combination Rev Limiter/altered timing curve ignition module. Which in my mind, one or the other is a must have device when running a Spec2 on a 787 with any bump in compression, maybe even without a bump in compression if you can tune that engine to turn in excess of 7200 rpm.
    I find 7200 rpm maximum to be very low rpm for even a stock motor with a Spec2, when I know it will do well past that when it is all tuned properly. So, if nothing else, at least a stock head and some kind of add on rev limiter. MT rev limiters came in the Spec2 kit. I believe it was the model that MT made for FPP that also had the ECWI wires coming out of it that told the EWCI solenoid when to open and close.

    You must be very carefull. Any 787 with a Spec2 can easily sieze pistons if anything in the setup is not set correctly, and be sure to put jets in the carbs that allow it to be a little on the rich side at high rpm.
    In otherwords, if you get it to tach out at 7400 rpm and the 'plugs look perfect, think about opening the high speed adjuster a little bit beyond wherever it is set at 7400, and open the adjuster to where it will ony do 7350 rpm. It is better to give back 50 rpm, than to do a top end job.

    Bill O'Neal
    WCM
    Last edited by Mr. Bill; 03-12-2010 at 08:19 PM.

  5. #5
    PWCToday.com Is My Home Away From Home Mr. Bill's Avatar
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    Re: 96 xp water routing?

    And do not try to run any impellor with more than 23.5 degrees in it with premimum pump gas. You will keep the engine overloaded at wot if you do. My choice is the Solas XO 16x23.5, or have Impros bend your oem to those specs. If you use a Skat Trak, just make sure it does not overload the motor. Some of their recommendations for a modified motor impellor are for modified motors using racing fuels, because a true modified motor will be using high octane racing fuel only, in the neghborhood of 106 to 118 octane, not this crap unleaded racing fuel that at maximum is about 101, no matter what they tell you it is. You cannot make unleaded to consistantly be more than about 101 octane maximum. It may be more than that at the refinery, but as soon as you remove the cap, within minutes, it will not be over around 101. It may even be less, depending how you stored it or how many hours it has been in your plastic jug or gas tank.

    An overloaded engine will detonate itself to death no matter what compression or what fuel is in it.

  6. #6
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    Re: 96 xp water routing?

    Thanks for all the good info, Yeah, I forgot to add that I have the MSD enhancer already as well. I run 116 octane fuel and usually ****tail it with quarter of 93.

  7. #7
    PWCToday Newbie RAZEWORLD's Avatar
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    Re: 96 xp water routing?

    Would that have a reversed effect on the bailers and flood the hull ?

  8. #8
    Tech Guru PWCToday.com Is My Home Away From Home Watercraft Magic's Avatar
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    Re: 96 xp water routing?

    Cooling hoses going to the head (or anywhere else on the motor/pipe/pump for that matter) have nothing to do with the functioning of the bailer/siphoning hoses. They are completely separate systems in terms of plumbing. Unless someone got completely confused and intermingled the systems somehow.
    email Chris at Watercraft Magic cdofixr1@live.com

  9. #9
    PWCToday Newbie RAZEWORLD's Avatar
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    Re: 96 xp water routing?

    Thank you.does the upgraded "C" clip work better than the "O" ring @ the carbon seal on the drive shaft ? Taking on to much water.If water flow was reversed would the bailers also be reversed ?The vacuum would be reversed at pump ? Needs the thrust of the pump and tuned exhaust and regulator ?..Just got this craft Oct.2017 have been going through it from front to back over the cold months. Just installed a bilge pump and switch for piece of mind.
    Last edited by RAZEWORLD; 07-05-2018 at 09:00 PM.

  10. #10
    PWCToday.com Is My Home Away From Home Matt Braley's Avatar
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    Re: 96 xp water routing?

    If your O-rings are missing between the pump and nozzles, if one or both of the plastic bailer tubes falls out of the reduction nozzle, or if the lines fall down inside the hull then the scuppers will bring in water instead pump it out.

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