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  1. #1

    2001 xp hard jetting

    Debating on hard jetting my xp. I've read in the racing manual to put a 200 in the muffler and a 150 in the tuned pipe to start. Can someone explain to me by going up/down in the jetting does what exactly? I had a great idea over last summer and never did this but I never up on it or more about it and forgot what I knew . So if someone can explain going up does what? and down in the jetting does what? Thanks for the help


  2. #2
    SURFnTURF's Avatar
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    Quote Originally Posted by jwick86 View Post
    Debating on hard jetting my xp. I've read in the racing manual to put a 200 in the muffler and a 150 in the tuned pipe to start. Can someone explain to me by going up/down in the jetting does what exactly? I had a great idea over last summer and never did this but I never up on it or more about it and forgot what I knew . So if someone can explain going up does what? and down in the jetting does what? Thanks for the help
    Waste of time and effort IMO, you are better off with a set of reeds and air filters.
    You can run water injection into the head pipe for better low to mid range power but running these drier at the top end will not give you more revs just burnt out exhaust hoses.
    I can give you the details on where and how much water to dump in the head pipe as it works very well.

  3. #3
    Quote Originally Posted by SURFnTURF View Post
    Waste of time and effort IMO, you are better off with a set of reeds and air filters.
    \
    Well as of right now I have f/a and jets without accel pump. I do have a set of rinaldi's, a 97.5 white pipe, and a Rossier head with 49cc domes. The only thing on the ski right now the is f/a. Everything else is being added on this spring one at a time to see where improvements have been made, or hurt.

    I am also going to have the timing advanced 1* as I had talked to people here before about. My prop has also been repitched by impros.

    My biggest thoughts were I don't know the effect of putting in a larger or smaller jet into either the head pipe or muffler. What will this change? I'm not worried about getting clogged up as I will be installing a main filter off the pump, plus an inline filter to each jet. Preferably a micron filter on the jets.

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    Quote Originally Posted by jwick86 View Post
    Well as of right now I have f/a and jets without accel pump. I do have a set of rinaldi's, a 97.5 white pipe, and a Rossier head with 49cc domes. The only thing on the ski right now the is f/a. Everything else is being added on this spring one at a time to see where improvements have been made, or hurt.

    I am also going to have the timing advanced 1* as I had talked to people here before about. My prop has also been repitched by impros.

    My biggest thoughts were I don't know the effect of putting in a larger or smaller jet into either the head pipe or muffler. What will this change? I'm not worried about getting clogged up as I will be installing a main filter off the pump, plus an inline filter to each jet. Preferably a micron filter on the jets.
    You have a good combination of parts, although I like the stock head better as it flows and cools a lot more efficiently.
    I would install the reeds,pipe and head in that order all at separate times and see what gains you experience.
    I did a 2000xpl with similar set up + a lightened flywheel and PTO outer weight removed with and it is a flyer.It would bump the rev limiter in smooth water.
    Forget the idea of hard jetting the pipe as it gives no gain,you are better off installing water injection into the head pipe.
    The stock pipe with water injection responds remarkable well with great low end pull and torque to match. Been running this set up since 99 on a few xpls and not once has the pipe overheated or the feed line blocked. The beauty with this system is the feed line never blocks up because it runs a 1/4 inch water flow direct to the head pipe.

    The trick is to dump HUGE amounts of water into it using a 90 degree brass fitting positioned in just the right spot on the head pipe. The fitting uses a 3/8 or 1/2 inch hole with the water flowing through a 1/4 inch barb fitting. On the head pipe there is a flat spot just above the front carby as per the picture ,drill and tap the pipe and install. Water is fed directly from the main water incoming line (just past the water box "T" plastic fitting) and install another "T fitting using 1/2 x 1/2 x1/4 inch then divert this to the solenoid then to the fitting.

    You need a water controller of some sort(MSD ,Microtouch,Factory pipe) to control water and a solenoid to stop water flow. I have my MPEM programmed to control this by Les Cooke here in Oz but isn't offered as a service any more.
    That is all the installing you have to do, now you need to control the water .
    I set these up with the solenoid in the open position(ON) from idle and have it turned off at 5500 rpm.
    Once set up you can easily test it on the trailer using the garden hose and hang the feed pipe overboard to see if it stop at 5500 revs. Sometimes i have had sticky solenoids that don't shut off very well but that's because of not flushing with fresh water often enough (lazy and too tired). If your revs don't get past 6500 the solenoid is letting water get past so check that first. Easy thing to do with great results.

    And forgot to clarify leave all the stock water lines in place as they work best the way they were designed. All this does is dump water into the header pipe and shut it off at 5500 revs.
    Few people have done this but when done correctly it works very well.

    Some people worry that having the solenoid in the open position will flood the pipe and engine with water but at idle water pressure is at its minimum and exhaust flow disperses all the water in the head pipe and does not flood the pipe because it is atomized into the hot gases then exited.
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  5. #5
    Are the jetworks valves worth it? I don't see why not on the waterbox?? Also, is there a valve like the jetworks only in reverse? Normally open then closes on pressure?

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    Your not listening hearing but not listening,the stock exhaust system works best with the OEM set up . The gains that people think by drying out the exhaust are unfounded, all what happens is they blow exhaust couplers due to not enough cooling water in the exhaust pipe.
    You wont get any real gains from changing jetting to the exhaust other than what I described.
    But saying that the best way to learn is by learning from your own mistakes.

  7. #7
    Does anyone know what the psi setting should be on the Jetworks flow valve to start with on a 951?

    I will be adding my mods 1 by 1 and start adjusting more from there.

  8. #8
    I got an MSD water injection setup for my 951. I am unsure if I need to run a jet inline with the solenoid, either before or after, to control the amount of water going to the spray bar. Does the spray bar spray the correct amount of water into the pipe? Or should I run a jet before to control the water amount? I would think you'd rather run the jet after the solenoid so the water doesn't have to fill a larger water line with a smaller opening. Any thoughts?

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    No don't run any jet in the line at all,you can run a 1/4 inch barb fitting directly into the pipe where there is no water jacket(as per the previous photo). Don't worry about dumping too much water into the pipe as long as it fully shuts of at 5500 rpm.I never used a spray bar fitting just an open ended 90 degree brass fitting that flowed heaps of water.
    I think with the MSD set up from memory it will only let water flow at above 3000rpm which is still ok but not ideal ,I had mine set up ON at engine start and OFF at 5500rpm.
    When you get it going if your revs stall at 6300-6500 the solenoid isn't turning off properly.
    You should notice a noticeable gain in acceleration below 5500rpm.

  10. #10
    Is the Micro Touch a better unit for this? I don't mind getting a different one, I only want to put this in once. Thanks for the help.

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