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  1. #1
    Join Date
    Oct 2009
    Location
    Virginia Beach, Virginia, United States
    Posts
    32

    Default Question on Balancing 1997 S150 Carbs

    My gummed carbs are on the bench. After cleaning / rebuilding I understand they should be balanced, best with vacuum gauges. I am not sure if I have the required intake vacuum ports. See pics. Each of the intakes has a "nipple" with a vacuum line attached. The vacuum lines go to whatever the pictured component is under the fuel filter area.

    Should I / Can I disconnect these lines to get the balancing vacuum gauges connected?

    Or must I balance with no gauges but using the eyeball on the butterfly method as described in the service manual?

    Sorry all pics are rotated. Don't know why.

    Click image for larger version. 

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    Last edited by tperk100; 02-14-2020 at 09:58 AM.
    Tom P in Virginia Beach, VA
    1997 Yamaha S 150 TXRV on a
    1997 Scout SportFish 192

  2. #2
    Join Date
    Nov 2011
    Location
    tennessee
    Posts
    4,203

    Default Re: Question on Balancing 1997 S150 Carbs

    No your motor is a 2 stoke and all you need is a sync and link on the shafts...4 stoke need to be balanced.
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  3. #3
    Join Date
    Sep 2010
    Posts
    19,100

    Default Re: Question on Balancing 1997 S150 Carbs

    Agreed----Those are not vacuum lines they are oil injection hoses from the oil pump !-----Do not run the motor with those hoses disconnected.-----Make sure those wee hoses are in good condition , with no chance of them breaking / falling off the nipples.

  4. #4
    Join Date
    Oct 2009
    Location
    Virginia Beach, Virginia, United States
    Posts
    32

    Default Re: Question on Balancing 1997 S150 Carbs

    Thanks much guys...very eye opening to a rookie mechanic like me.
    Tom P in Virginia Beach, VA
    1997 Yamaha S 150 TXRV on a
    1997 Scout SportFish 192

  5. #5
    Join Date
    Oct 2009
    Location
    Virginia Beach, Virginia, United States
    Posts
    32

    Default Re: Question on Balancing 1997 S150 Carbs

    Finally - Carbs installed. Fresh gas. With fingers crossed, went to start engine submerged in 1/2 of 50 gal drum. First noticed that primer bulb now gets hard to where it can't be pumped any more. It has NEVER done that before and I always wondered why. Cranked her up and was pleasantly surprised. Started right up. Idles faster than before. VERY responsive when punching throttle. Can't wait to get her on the water. But before that I need some help with tuning.

    When I worked carbs, I set idle mix screws to same amount of turns as they were when I took carbs off. Read that to tune them just turn them for fastest idle. I turned two of them and could not detect any difference by listening to idle. Is this important? If so, how do I adjust them?
    Thanks much!
    Tom P in Virginia Beach, VA
    1997 Yamaha S 150 TXRV on a
    1997 Scout SportFish 192

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