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  1. #11
    Quote Originally Posted by boudin View Post
    Aftermarket F/As should require a richer mixture. Did you change the jets to match the Oside Bill formula?

    http://www.greenhulk.net/forums/show...=1#post1951162


    -Greg
    Yeah, I run 135 and 100's according to Oside Bill's recipe for 1200 no chokes, aftermarket f/a's. That's where the 1 1/4 and 1 1/2 turns out came from as well.

    ncdoo, I have the choke removed so unfortunately can't test it that way.

    Also, up to this point, I've not tested the ski with the hose. I put it under load every time. I was hoping I could at least eliminate something on the hose before making the trip to find out I need to pull the carbs and make more changes.

  2. #12
    mudslanger's Avatar
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    If you were running factory air box your jetting would be ok. But with aftermarket F/A you should go at least 110 on the low. You are now more than 1200cc with the oversized pistons witch means more fuel for the extra air and more fuel for flame arresters. I might would even go 115 then tune down. Also check all the reeds to make sure they are sealing properly. Just because they look good doesn't mean they are sealing properly. Also to properly check the low side to half throttle you should tune it on the trailer backed in the water. When you start from idle and slowly giving it throttle all the way to half or more throttle there should be no hesitation. Start at 1.5 turns out on the low and tune down from there it should be rich. Keep us updated on progress.


  3. #13

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    To me, it sounds like your out running your fuel supply, since you have done the balancing mod,,it is very easy to put a tee in line before the restrictor and see if you have at least 4psi when it starts rolling back on rpm.

  4. #14
    Quote Originally Posted by mudslanger View Post
    If you were running factory air box your jetting would be ok. But with aftermarket F/A you should go at least 110 on the low. You are now more than 1200cc with the oversized pistons witch means more fuel for the extra air and more fuel for flame arresters. I might would even go 115 then tune down. Also check all the reeds to make sure they are sealing properly. Just because they look good doesn't mean they are sealing properly. Also to properly check the low side to half throttle you should tune it on the trailer backed in the water. When you start from idle and slowly giving it throttle all the way to half or more throttle there should be no hesitation. Start at 1.5 turns out on the low and tune down from there it should be rich. Keep us updated on progress.
    Great, I'll jet up and test. What's the best way to test the reeds even though they pass the measurement specs?

  5. #15
    Quote Originally Posted by Crazypirate View Post
    To me, it sounds like your out running your fuel supply, since you have done the balancing mod,,it is very easy to put a tee in line before the restrictor and see if you have at least 4psi when it starts rolling back on rpm.
    I'll do this as well, good to have regardless of my problems. Thanks!

  6. #16

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    What are the condition of your fuel pumps?

  7. #17
    Quote Originally Posted by TCR View Post
    What are the condition of your fuel pumps?
    Excellent, the carbs were just rebuilt with OEM Mikuni kits. Only about 3 hours of use.

  8. #18

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    Did you drill out the returns? What jet are you running in the return line? What's your current fuel pressure? (Idle/wfo)You should probably check the condition of the fuel pick up and fuel filter as well.

  9. #19
    mudslanger's Avatar
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    Quote Originally Posted by jhawker23 View Post
    Great, I'll jet up and test. What's the best way to test the reeds even though they pass the measurement specs?
    One easy way is to think of the reed as a boat and put it in a pan of water and push I'd down and see if water is seeping in. If water is running in and filling them up you may get by with pulling off the pedals and cleaning them and putting them back together. Normally I clean and blow them with compressed air. Then spray them with WD40 when you do this you can see them make a seal all the way around the pedal. If they are making a seal you will see it the edges get dark where the pedal touches the reed cage. If it's not sealing the pedal will be all white around the edges like it's not touching the reed cage.

  10. #20
    Yamaha artisan Cutlass's Avatar
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    Quote Originally Posted by mudslanger View Post
    If you were running factory air box your jetting would be ok. But with aftermarket F/A you should go at least 110 on the low. You are now more than 1200cc with the oversized pistons witch means more fuel for the extra air and more fuel for flame arresters. I might would even go 115 then tune down. Also check all the reeds to make sure they are sealing properly. Just because they look good doesn't mean they are sealing properly. Also to properly check the low side to half throttle you should tune it on the trailer backed in the water. When you start from idle and slowly giving it throttle all the way to half or more throttle there should be no hesitation. Start at 1.5 turns out on the low and tune down from there it should be rich. Keep us updated on progress.
    For the record, I completely disagree with this advise. Not trying to be a dick, I swear. No one in the Yamaha 65u world is jetting the lows to 110 or 115 on a stockish engine with flame arrestors. Even with overbored cylinders/pistons. I'm not even sure if the all out Big Overbore guys are. Jhawk, how big is your overbore??
    And another correction needs to be made. I don't think you can overbore a 65u to get the cc over 1200cc. These "1200's" start out at 1131cc. You need to bore and stroke to get to 1200cc or more.

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