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  1. #1

    Using Bens jetting specs with non ethanol fuel

    I've replaced the grey fuel lines and cleaned the carbs with the help of the forum however there is still a lot of hesitation down low and it will sometimes shut off or stall when given full throttle. I was running carb cleaner in a fresh tank of petrol and the engine performed better the more I rode but I'm going to do a complete rebuild of the carbs when I get home. Before anyone says anything I checked the plugs and it's not showing the engine running dangerously lean.
    If I follow the initial jetting specs Ben posted up with PROK filters will I have any problems with our fuel in Australia? I run on what you guys call 94 AKI (98 RON) as it's available at most "gas stations" and is the best we have but it doesn't have any ethanol. I saw that the 2.3 needle was recommended because your fuel can have up to 15% ethanol.
    I'll be using the ski exclusively at sea level in temps from 60-100 Fahrenheit (18-37 Celsius)

    Should I have enough adjustment with the screws to not cause an overly rich mixture or will the 2.3 needle and 85 lows 167.5 mains be too big?

    The plan is to rejet and rebuild the carbs, replace the airbox, change the sponsons to a set of beach house ones and then leave it

    it's a 98 GTX Limited with 151 hours and 140psi compression when cool-warm


  2. #2
    flyin' the friendly skies airbornexp's Avatar
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    follow the jetting specs you will be fine. you wont have to adjust the screws too much as thats why you get bigger jets. as for the fuel, in the states we prefer non-ethanol fuel if you can find it. you dont need to run 93+ octane. run the regular 85 octane its better for your engine actually. you dont gain anything running 93+.

  3. #3
    Quote Originally Posted by airbornexp View Post
    follow the jetting specs you will be fine. you wont have to adjust the screws too much as thats why you get bigger jets. as for the fuel, in the states we prefer non-ethanol fuel if you can find it. you dont need to run 93+ octane. run the regular 85 octane its better for your engine actually. you dont gain anything running 93+.
    Why do you say the lower octane fuel better for your engine? I like that the extra knock resistance of the 94 fuel provides a safety margin if it runs lean at the expense of 10c/L which I'm happy to pay. I'm not trying to argue with you I'm just interested as to your reasons

  4. #4
    The 2.3 N/S will be fine with our Aussie fuel.
    I also always use 98 octane - for the same reasons.
    Get rid of the Accelerator Pump & bump up the LS jets to either a 95 or a 97.5.
    There is a big difference between how the USA sets up these 947's and how the Aussies do.
    This might be a good read for you - from a local Forum:
    http://www.ozpwc.com/forum/showthrea...ols-of-Thought

  5. #5
    cheers for the info/link deafwish, now I'm even more unsure on which way to go. The stock needle is 2.0 right?

  6. #6
    flyin' the friendly skies airbornexp's Avatar
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    Quote Originally Posted by AusAnton View Post
    Why do you say the lower octane fuel better for your engine? I like that the extra knock resistance of the 94 fuel provides a safety margin if it runs lean at the expense of 10c/L which I'm happy to pay. I'm not trying to argue with you I'm just interested as to your reasons
    Its really up to you, there is no gain by it. If I can find the thread or post regarding this topic I will post it. I think member 96XPSS posted it a long time ago...

  7. #7
    From what I have researched, it all comed down to the total number of points (adding LS number to HS number) in the carb' to safely run your ski.
    Both the USA way & AUS way seem to end up with about the same point number - so I'm assuming the end result is similar.
    I'm running disabled A/P's, 95 gram springs, 100 LS and stock 162.5 HS with a 2.3 N/S.
    My setup equates to 162.5 - which is the same point number as 'Ben's' 95 LS & 167.5 HS jet kit.
    Guys have successfully been running this type of setup reliably for years over here - in both rec' and race boats.
    p.s. Where in AUS are you situated?

  8. #8
    Quote Originally Posted by deafwish View Post
    From what I have researched, it all comed down to the total number of points (adding LS number to HS number) in the carb' to safely run your ski.
    Both the USA way & AUS way seem to end up with about the same point number - so I'm assuming the end result is similar.
    I'm running disabled A/P's, 95 gram springs, 100 LS and stock 162.5 HS with a 2.3 N/S.
    My setup equates to 162.5 - which is the same point number as 'Ben's' 95 LS & 167.5 HS jet kit.
    Guys have successfully been running this type of setup reliably for years over here - in both rec' and race boats.
    p.s. Where in AUS are you situated?
    I'm in Perth. What other mods do you have and what ski is it? Was it hard to disable the A/P's? I'm ordering a primer kit so it negates the reason I was thinking of keeping the A/P

  9. #9
    2000 XPL, 98 exhaust hose, Franco Curve MPEM, half a headgasket, Tau Ceti F/A's, jet kit (no A/P's), Solas Concorde & some bling/ handling bits.
    A primer kit is for cold starts. A/P's are for throttle response - due to the tiny factory spec' LS jets (to meet emissions).
    Your ski would fall on it's face from being very lean - if you disabled the A/P's & kept the factory LS jets.
    You can simply bend the actuating arm out of the way to disable it.
    I'm originally a Perth boy (went to Mt Lawley SHS) but now live in Melb!
    The 947 was (and still is) a competitive engine in Oz & there's a stack of smart blokes on OZPWC who have had extensive experience with tuning them!

  10. #10
    Quote Originally Posted by deafwish View Post
    2000 XPL, 98 exhaust hose, Franco Curve MPEM, half a headgasket, Tau Ceti F/A's, jet kit (no A/P's), Solas Concorde & some bling/ handling bits.
    A primer kit is for cold starts. A/P's are for throttle response - due to the tiny factory spec' LS jets (to meet emissions).
    Your ski would fall on it's face from being very lean - if you disabled the A/P's & kept the factory LS jets.
    You can simply bend the actuating arm out of the way to disable it.
    I'm originally a Perth boy (went to Mt Lawley SHS) but now live in Melb!
    The 947 was (and still is) a competitive engine in Oz & there's a stack of smart blokes on OZPWC who have had extensive experience with tuning them!
    I'm just next to mt lawley in Bayswater

    I understand what the AP's are for but I was going to keep them as you can still use them like a primer if you pump the throttle a few times before starting, as I'm getting a primer kit they aren't really needed anymore.
    I'll do some more digging on OZPWC tonight and try to figure things out before I have my order shipped from the states on monday.

    Where do you get parts from locally? Does the solas perform well with the mods you've got or are you planning on doing more mods down the track?

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