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Thread: stock exhaust

  1. #1

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    stock exhaust

    have caught wind that i should remove freeflow from ski. getting ready to install vf3 so it would be perfect time to make the swap. am i missing power due to freeflow? what about heat? 2003 gpr 1300 head milled, vf3, efi, and arrestor are the motor mods i have.


  2. #2
    ABBOTT's Avatar
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    TO FREE FLOW OR NOT TO FREE FLOW???

    the 1200's (1200 water boxes that is) need the free-flow in most cases because there is an extra baffle inside the 1200 water box that helps keep the backpressure up to par.

    the 1300 (1300 water boxes) is missing that same baffle in the water box, therefore needs the stock sound supression to keep the proper amount of back pressure, whereas the 1200 boxes can live without the stock sound suppression, however may not help much either (if anything). But definitely will be louder.

    So what do you lose when switching to Free Flow on a 1300 water box? I lost almost 50 RPM's because i didn't know any better, but in return it sure sounded mean as hell. Lots of others that have tested this have reported losing close to the same number of RPM's which equates to about .4-.5 MPH loss on top (all depending on certain circumstances).

    So what do you lose when switching to Free Flow on a 1200 waterbox? Nothing that i am aware of unless someone wants to chime in and correct me on that one.

    So does engine size matter? I wouldn't think so, i would venture to say that the determining factor will be only the water box itself (no matter how big the engine size). So in essence, you could have a 1300 stock boat and run a 1200 water box with the free flow and may not lose a drop. This can be a mix and match game to a certain extent.

    I would say that different boats are going to need different things to satisfy the maximum RPM's out of it, for example:
    --a tripple pipe (to my knowledge) will always need free flow no matter if it's a lawnmower engine or a 1500cc engine.
    --a single pipe may have some weird needs (away from the norm) depending on things like the D-Plate Mods, or if it still has a Cat-Con.
    --So there isn't only one correct answer to these questions, but the ones with the serious correct answers this deep will have to come from the hard core tuners out there, and maybe they will chime in and help me out on this one if i left anything out.

    Hope that this helps to simplify it a little.

  3. #3

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    Here is another one of those free tips most people are looking for

  4. #4

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    No volunteers here for a free flow of information! It amases me that in a recent thread the concensus was that "the forum should return to a free exchange of information" and in another recent thread the concensus was that those who paid for information gathered in part from this and Riva's forums should be protected. I don't know what is fair or moral, but I do know that a free flow of information is inconsistent. Years ago Karl from Island Racing posted some speeds and he was dubbed a lying weinker (i before e, except after c, or when sounding like a, as in neighbour and weigh). Slowly people started using his repitched and setback impellors, then started paying him to modify rideplates. Now some of you guys may be paying for his specs, or if not his ideas! So what about freeflows? I think a free flow of information will give you the answer, and I suspect that on a 1300 you either leave the sound suppression in, or fit the sound suppression along with a jet works valve (3/8 not 1/3) to dump in a lot of water and emulate or even increase the backpressure. I also suspect that no-one who really knows the answer has the guts to post it. Free flow or info free flow? REXA.

  5. #5
    txgp1300r's Avatar
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    someone send me the black rubber tube that connects waterbox to black plastic muffler and ill test it.....i chopped up my stock tube and have been wanting to to a test but cant install due to no tube.....lot of work for a test

  6. #6
    Moderator OsideBill's Avatar
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    Abbott had some great points and i never knew there was a difference between the 1300 and 1200 waterbox. so this said has any one tried a 1300 waterbox in a 1200? with or without freeflow? and in reply to REXA I believe the jetworks merely dries out the waterbox at low rpms for hole shot purposes and then allows a free flow of water to achieve proper back pressure once target RPM is reached.

    my $.02

    OsideBill

  7. #7
    I too was gonna try going back to stock sound suppression to test and tune on my ski...This seems to me to be one of those things that works for one may not for another so you should test your own set-up...I have a 1300 EFI ski and my question is can i put back in my sound suppression without the foam in there and will it hold up without foam or something in it's place to support the sound suppression tube? My ski should be back up and running next weekend and i'm going to test and tune a lot of things in question i've learned on here..sound suppression,prop cone,sponson settings,trim tabs,etc...The only way to find out what works on your ski is try it on your ski....
    my .02 worth

  8. #8

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    You can refit the sound supression without foam in place, it is there for buoyancy and not support. I know that the idea of the jetworks is to dry out the water box at low revs for holeshot. But I also know that feeding the water from the pump direct will give far more flow, especially thru a 1/4 valve etc. There is always a kerfuffle about making sure that the inlet and outlet and hoses etc are 3/8 and not 1/4. Also there was, a year or two ago, a thread that indicated that the hose had to be jetted to re-introduce revs lost when the conversion was done from sound suppression to free flow, and that if done properly then you could actually get 30 more rpm's again! The jts were homemade with sises of 5, 5.5 and 6mm I think. We need a free flow of information on this one to save a lot of needless expirementation. Remember when DMD spat the info on sponson stepping? Saved a lot of grief. REXA.

  9. #9
    txgp1300r's Avatar
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    someone hurry up and test this so i dont have to...otherwise im doing it as soon as i get the big black rubber exhaust connector..

  10. #10
    Mike xsockguyx's Avatar
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    bump

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