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  1. #1
    Super7Four's Avatar
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    help with free flow exhaust

    I'm getting ready to install the Riva FF exhaust kit on my 15F. There look to be two sets of installation instructions. One seems to just bypass the secondary muffler while the other seems a little more complicated which also modifies the primary muffler. Can anyone tell me what additional benefits there are from the more complicated installation. Also, this one seems to include some type of bypass outlet at the rear of the ski...can you tell me what this does and why it isn't used in the more simple set up?

    Any help would be greatly appeciated

    Thanks


  2. #2
    Moderator #985 lasportsmn's Avatar
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    Quote Originally Posted by Super7Four View Post
    I'm getting ready to install the Riva FF exhaust kit on my 15F. There look to be two sets of installation instructions. One seems to just bypass the secondary muffler while the other seems a little more complicated which also modifies the primary muffler. Can anyone tell me what additional benefits there are from the more complicated installation. Also, this one seems to include some type of bypass outlet at the rear of the ski...can you tell me what this does and why it isn't used in the more simple set up?

    Any help would be greatly appeciated

    Thanks
    As far as the bypass, Riva said that is to keep the amount of water in the waterbox at idle to a minimum so you will get a quicker throttle response after idling. Not needing to blow out the water. I chose to not do it and really have no problem. If you are not racing bypass the bypass.

    The waterbox mod allows more air to flow. It defetes the purpose to do the FF without it. You only have a small hole in the WB so it opens it up alot and the pictures show in the instructions

  3. #3
    Super7Four's Avatar
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    Quote Originally Posted by lasportsmn View Post
    As far as the bypass, Riva said that is to keep the amount of water in the waterbox at idle to a minimum so you will get a quicker throttle response after idling. Not needing to blow out the water. I chose to not do it and really have no problem. If you are not racing bypass the bypass.

    The waterbox mod allows more air to flow. It defetes the purpose to do the FF without it. You only have a small hole in the WB so it opens it up alot and the pictures show in the instructions
    Thanks for the reply. I certainly don't do any real racing. So, you did everything in the instructions with the exception of the bypass?

    Did you get any performance gain from the FF exhaust? I have the power filter which did help a bit but hoping to get more with the addition of the exhaust.

    Thanks again

  4. #4
    Moderator #985 lasportsmn's Avatar
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    Quote Originally Posted by Super7Four View Post
    Thanks for the reply. I certainly don't do any real racing. So, you did everything in the instructions with the exception of the bypass?

    Did you get any performance gain from the FF exhaust? I have the power filter which did help a bit but hoping to get more with the addition of the exhaust.

    Thanks again
    Yes I did everything except the bypass. I had only .5mph increase but did notice better hole shot.

  5. #5
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Did you do the mod by the riva instillation or did you make the hole bigger?

    Sean

  6. #6
    Moderator #985 lasportsmn's Avatar
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    Quote Originally Posted by smokeysevin View Post
    Did you do the mod by the riva instillation or did you make the hole bigger?

    Sean
    I guess it was done as per the instructions. I had someone else do it for me. I can't tig to save my life. I don't see why you couldmot make it bigger. I didn't ask Riva why they chose that size hole and not just to completely cut out the entire baffle.

  7. #7
    Super7Four's Avatar
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    Did you cut the baffling out of the primary waterbox? If so, do you know if this was just for sound or whether it provides some performance gain

    Thanks

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    I'm just guessing the reason why they didn't cut the baffle completely out is to maintain some intergrity to the muffler and keep some of the back pressure. I was thinking about deleting the water boxes, aka mufflers all together but after talking with some folks here and at riva i decided against it.

  9. #9
    Moderator #985 lasportsmn's Avatar
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    Quote Originally Posted by STX-15FER View Post
    I'm just guessing the reason why they didn't cut the baffle completely out is to maintain some intergrity to the muffler and keep some of the back pressure. I was thinking about deleting the water boxes, aka mufflers all together but after talking with some folks here and at riva i decided against it.
    +1
    I only had a hole drilled just not sue of the actual size but I am sure it was close to the instructions.

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