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  1. #1
    Fumatelo tokeytokertin's Avatar
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    Carb Rebuild and Gas valve Install(Now Tuning)

    Finally getting around to doing my much needed maintenance. My ski is a 2001 GPR with 300 hours. The engine was rebuilt at around 250 hours. The carbs have not been touched. I have accumulated many parts here on the classifieds and i need a little advice on what is the best combination of parts to install for a reliable snappy ski with a full range of throttle control. The following is the list of parts:

    1. 3 original mikuni rebuild kits (jets as per oside)
    2. riva gas valve set with new bellows and gaskets
    3. dominator intake
    4. pro-tech head
    5. riva triple fuel pick up
    6. riva f/a's
    7. complete OE gasket set
    8. primer kit
    9. oil injection block off kit
    10. riva stinger 1
    11. t-handle carb adjusters

    any help is appreciated
    Last edited by tokeytokertin; 06-14-2011 at 07:50 AM.


  2. #2
    Fumatelo tokeytokertin's Avatar
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    forgot to mention that i have already installed a solas 13/19 and a riva intake grate. I have also aquired jim's ride plate and a ss intake grate. i am aware that these parts are for top end and that they go against my goal but i wanted them just in case i wanted to switch to a top end type ski.

    FYI

  3. #3

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    Try to find a base line speed for your boat as it sits right now using a GPS. You will not know how much your boat has improved if you do not do this. This is the point where you "tune" all of the hull components to get the most out of them that you can.

    Normally, you would install aftermarket upgrades one component at a time so that you can tell if they are an improvement or not. You would adjust your craft to get the desired effect and would not move any futher until you got what you expected. The head is a different animal. In the case of a GPR, when you install the head, you must rejet the carbs as well.

    Get your self a good tachometer. Do not do anything under the seat until you do.

    Remove the head and carbs. Clean and rejet the carbs per OsideBills specs. These are tricky suckers with may ways to mess up, so be sure to get someone who knows what they are doing to help you the first time out of the gate. OsideBills' jetting takes into consideration the addition of aftermarket flame arrestors, so these can be installed at this time as well.

    Remove the oil injection system and put on the block off plate. You can install the primer at this time as well. These mods are for convienience sake and should not effect the overall performance of the boat, and since your at a point where it is easy to get to them, then why not.

    Get your self a good tachometer. Do not do anything under the seat until you do

    When you begin to put your boat back together, use the Stinger 1. It will be easier for you to adjust the carbs and get them tuned accurately.... ie. the low speed adjustments are hard to get to with the stock stinger. When the carbs are tuned as close as possible, then go back with the stock Stinger to get higher rpms. All you should have to do is increase the high speed jets a tad to regain your (100) rpms and top speed.

    The gas valves are really handy to clean and service as well as have a very good reputation for not failing (I've lost one myself). They are however not going to improve your overall top speed. The mechanical power valves give you linear power (like an automatic transmission), whereas the gas valves give you the impression that you are shifting gears. Save this upgrade for when you have your boat running as well as it can with the mechanical valves.

    Get your self a good tachometer. Do not do anything under the seat until you do.


    This is just a starting point. I'm sure there will be many questions along the way.

    By the way, you really should get a good tach.......

  4. #4
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    you need vf3's in there and remove all the factory crap from the carbs also the triple fuel pickup is not needed, its for triple pipes that suck fuel hard core. also do not run outwears on your riva f/a's they rob rpm's big time...like 300rpm...

    might as well put a rule bilge pump while your at it so you can mod your pump and remove the bilge line and clean the exit nozzle up till you snaffle an 05 pump setup with 2" extension.

    i did a full rebuild over a few years on my 02 gpr, its in the yami project sections if your interested in ideas and pitfalls.

    hope this helps and good luck with the mods

  5. #5
    Fumatelo tokeytokertin's Avatar
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    Thanks for your reply salty. This forum is great!!!

    Quote Originally Posted by salty View Post
    Try to find a base line speed for your boat as it sits right now using a GPS. I confirmed my top speed via GPS a while ago 68.9mph 3 run average. You will not know how much your boat has improved if you do not do this. This is the point where you "tune" all of the hull components to get the most out of them that you can.

    Normally, you would install aftermarket upgrades one component at a time so that you can tell if they are an improvement or not. i'm not really looking to break any speed records i just want a reliable ski with all preventative measures taken (ie power valve failure, oil line nightmare, restrictive oe intake, irregular oe jetting...). You would adjust your craft to get the desired effect and would not move any futher until you got what you expected. The head is a different animal. In the case of a GPR, when you install the head, you must rejet the carbs as well. The following are the jetting specs i'm going to use (as per Oside):

    SBNSPRING-SQ PUMP 95 GRAM- 13-0117 / 006-451 3 ea

    125 MAIN/HIGH SPEED JET MIKUNI - N102/221-125 3 ea

    110 PILOT/LOW SPEED JET MIKUNI - N100/606-110 3 ea

    SBN CARB - 1.5 NDLE & SEAT 3 ea


    He said this would be fine with the head and stinger. No Socks on the F/A's.

    Get your self a good tachometer. Do not do anything under the seat until you do. I've got a pet 2500 ready to be installed.

    Remove the head and carbs. Clean and rejet the carbs per OsideBills specs. These are tricky suckers with may ways to mess up, so be sure to get someone who knows what they are doing to help you the first time out of the gate. This isn't my first carb rodeo. OsideBills' jetting takes into consideration the addition of aftermarket flame arrestors, so these can be installed at this time as well. See above.

    Remove the oil injection system and put on the block off plate. You can install the primer at this time as well. These mods are for convienience sake and should not effect the overall performance of the boat, and since your at a point where it is easy to get to them, then why not.

    Get your self a good tachometer. Do not do anything under the seat until you do

    When you begin to put your boat back together, use the Stinger 1. It will be easier for you to adjust the carbs and get them tuned accurately.... ie. the low speed adjustments are hard to get to with the stock stinger. This was my plan, you read my mind! When the carbs are tuned as close as possible, then go back with the stock Stinger to get higher rpms. All you should have to do is increase the high speed jets a tad to regain your (100) rpms and top speed.

    The gas valves are really handy to clean and service as well as have a very good reputation for not failing (I've lost one myself). They are however not going to improve your overall top speed. Not looking for top speed just reliability and peace of mind. The mechanical power valves give you linear power (like an automatic transmission), whereas the gas valves give you the impression that you are shifting gears. Can the springs be adjusted to give more of a linear power curve? stiffer springs maybe? Save this upgrade for when you have your boat running as well as it can with the mechanical valves.

    Get your self a good tachometer. Do not do anything under the seat until you do.


    This is just a starting point. I'm sure there will be many questions along the way.

    By the way, you really should get a good tach.......
    Thanks again for your help. I'm starting the carb rebuild today.

  6. #6
    Fumatelo tokeytokertin's Avatar
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    Thanks izzo for your response.

    Quote Originally Posted by izz0 View Post
    you need vf3's in there that's my Christmas present from my wife this year and remove all the factory crap from the carbs also the triple fuel pickup is not needed any one need a triple pick up?, its for triple pipes that suck fuel hard core. also do not run outwears on your riva f/a's they rob rpm's big time...like 300rpm... not going to run the socks

    might as well put a rule bilge pump i have one waiting to be installed while your at it so you can mod your pump and remove the bilge line and clean the exit nozzle i got rid of the oe plastic nozzle and installed an sho nozzle up till you snaffle an 05 pump setup with 2" extension.

    i did a full rebuild over a few years on my 02 gpr, its in the yami project sections if your interested in ideas and pitfalls.

    hope this helps and good luck with the mods
    Thanks again for your time

    I will keep you all updated with my progress with pictures.

  7. #7
    Fumatelo tokeytokertin's Avatar
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    Thumbs up

    IT'S ALIVE!!! She fired right up. Finally found the time to finish the rebuild. everything went well. No leaks on the stand. Going to water test in the canals by my house tomorrow. I will post the results.
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  8. #8
    Fumatelo tokeytokertin's Avatar
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    Well, took her out and she runs. No leaks. The only thing is i have a slight low end bog. Once the gas valves open up the ski takes off. but the first few seconds starting off it hesitates. The plugs look good not too dark and not too light. Should i open or close the low end adjusters. Thanks for your help.
    Last edited by tokeytokertin; 06-24-2011 at 12:15 PM.

  9. #9
    Fumatelo tokeytokertin's Avatar
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    After doing some reading i have found that green bellows are for triple pipe skis and black ones are for single pipes. Also i'm using the red springs. Do you guys think that maybe this could be the source of my low end bog? I'm going to try to tighten the gas valve adjustment caps to try to get a little more tension on the springs a n hold the valves closed a little longer for some more back pressure. if this doesn't work i'll start in on tuning the carbs.

    What do you guys think.
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  10. #10

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    Quote Originally Posted by tokeytokertin View Post
    After doing some reading i have found that green bellows are for triple pipe skis and black ones are for single pipes. Also i'm using the red springs. Do you guys think that maybe this could be the source of my low end bog? I'm going to try to tighten the gas valve adjustment caps to try to get a little more tension on the springs a n hold the valves closed a little longer for some more back pressure. if this doesn't work i'll start in on tuning the carbs.

    What do you guys think.


    The green bellows are stouter than the black ones and retain their shape longer. You can use either. The red springs are fine.

    Gas valve adjustment: (you have the right idea)

    For right now stay focused on the bottom end reguardless of weather the problem is the gas valves or your carb adjustments. Once this is right, then you can go to the top end. If you have worked on carbs, I'm sure that you are aware of this.


    To get a better bottom end, crank down on them. If you go to far, then you will loose top end because the valves will potentially will not go all the way up. But this is a quick way to find out if your low speed jets are adjusted properly. Once you get your bottom end, readjust to get your top end back. If you adjust down and still do not get a good bottom end, then think carb.

    Typically, with your set up, the low speed adjustments would be 3/4 to 1 full turn out. Keep adjusting out from there in 1/8 to 1/4 increments. If you are out 2 full turns and still not getting the love you need, try chokeing the carbs slightly, moving up to half way choked. (Hit it with the primer on the bottom if you pulled your choke and plates). If it wakes up on the bottom, but then fades on the top end, you just need to rejet to the next larger size on the low end.

    As a last resort, that is if you cannot seem to get more gas to the bottom with out rejetting, you can use duct tape to "tape" closed or partially restrict the flow on 1/2 of your flame arrestors. This will help to create move vacume on your carbs and draw more fuel in on the bottom. If you are lean on the bottom this restriction will help pull more fuel in. If this works, you will know to rejet with out actually having to pull the carbs.

    Your Stinger 1 ought to make this all easy.

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