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  1. #1

    How to tune 3 carbs on SL750?

    I've tune a single carb on a 550 sxi, pretty easy. My question is how do you tune 3 carbs at the same time? I'm worried that one might be running lean the other rich and the last right on?

    My current problem is that I just rebuilt my center cylinder piston and ring and I replaced the fuel pump with a high volume pentigon pump, and I added an extra 50:1 premix for break-in. I starts fine and idles well in fact its pretty snappy up to 4100 RPM (out of water), I has a difficult time past that. Could it be my high speed curcuit on the carb or could it be electrical rev limit?

    I opened the electrical box and disconneted the temp sensors (brown wires) to help fault isolate, still the same problem. So, I'm guessing it's a carb issue.

    Does anybody know what size carb was put on a 1994 SL750 (38mm or 40mm)? What setting should I start at for the high speed carb setting?

    Joey


  2. #2
    Moderator beerdart's Avatar
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    Welcome to the hulk.
    It is impossible to tune out of the water. The stock settings are
    750 - Low Speed – 1/2
    High Speed – 1m, 1/2c, 3/4p

  3. #3
    Thanks for the response...

    In the past when I tuned my 550sxi in the water (example high speed) I would back my trailer into the water (ski still attach) and tune. For the high speed I would pin the throttle and adjust the needle until the max RPM (lean) was reached then back the needle off just a bit (1/8 counter clockwise).

    1) With the three carbs on the 1994 SL750 due I start from the factory setting and adjust all three the same amount? If I do, couldn't one of the cylinders be to lean?

    2) What size carb comes with this maching 38mm or 40 mm?

    3) Will the rich break-in oil mix prevent the machine from rev past 4100 RPMs?

  4. #4
    Moderator beerdart's Avatar
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    The carbs are Mikuni SBN 38mm with 34mm venturies. To tune it right you need to do plug chops and read the plugs and piston wash. Check the tech section for the process.

  5. #5
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    50:1 is not rich. You should be using 40:1 for break in.

  6. #6
    Moderator beerdart's Avatar
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    Quote Originally Posted by xlint89 View Post
    50:1 is not rich. You should be using 40:1 for break in.
    I think he still has the oil pump connected.
    PS: Nice score on the tau cetis!!!

  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Thanks for the hook up! Oh and the price was nice too.

  8. #8
    Moderator beerdart's Avatar
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    Quote Originally Posted by xlint89 View Post
    Thanks for the hook up! Oh and the price was nice too.
    After i get mine and engrave them. Let me know if you want custom engraving on yours??

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    I appreciate the offer, but it's more insulting to lose to an UGLY ski.

  10. #10
    Thanks for the info..... And yes I still do have the fuel pump hooked up.

    1) With the 50:1 premix and the oil pump running I'm at a 25:1 mix. Do you this will cause a problem in adjusting the carb high speed curcuit?

    2) On this machine is there a rev limiter and if so is it controlled by the CDI box? How would I bypass?

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