Factory B&S carb tuning instructions...confusing

  1. Welcome to 6x6 World.

    You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

    If you have any problems with the registration process or your account login, please contact us. Looking forward to seeing you in the forums and talking about AATVs!
+ Reply to Thread
Results 1 to 7 of 7

Thread: Factory B&S carb tuning instructions...confusing

  1. #1
    Join Date
    Nov 2019
    Location
    Illinois
    Posts
    106

    Factory B&S carb tuning instructions...confusing

    Trying to tune my carb using these instructions but I'm confused about a few things. At the beginning it references two different idle mixture screws, depending on which carb you have one is equipped with a RED screw and the other WHITE. It doesn't specify which carb comes with what screw and mine looks neither red or white. My carb is a Nikki part #808069 Then, a few steps later it says to "turn the valve" a certain way. What valve?!! Is there a screw or something that is also referred to as a valve? My guess would be what the instructions refer to as the air fuel mixing screw because it looks and I believe functions similar to a needle valve but I'm not certain on that. Could someone please shed some light on this for me. I've got snow to plow and this carb tune is keeping me from doing that. Thanks in advance...Cup
    Last edited by Cupwalker; 01-02-2022 at 03:59 PM.

  2. #2
    Join Date
    May 2009
    Location
    NJ 08533
    Posts
    4,986
    If it is a 1bbl carb there is only one adjustment, that is the black capped needle on the flywheel side of the carb, 2 bbl will either have 2 needles on top or screws under a plate on top.
    Some newer carbs are sealed but the needle may be under a plug.


    My new beer holder spilled some on the trails - in it's hair and down it's throat.
    Joe Camel never does that.

    Advice is free, it's the application that costs.

  3. #3
    Join Date
    Nov 2019
    Location
    Illinois
    Posts
    106
    Quote Originally Posted by ARGOJIM View Post
    If it is a 1bbl carb there is only one adjustment, that is the black capped needle on the flywheel side of the carb, 2 bbl will either have 2 needles on top or screws under a plate on top.
    Some newer carbs are sealed but the needle may be under a plug.
    It's a 1bbl carb with what Briggs calls an "idle mixture screw" located on the same side as the flywheel. They call the other screw the "idle speed adjustment screw" which is what sets the travel of the "throttle lever". As of right now the idle mixture screw seems to be doing nothing when I turn it in or out so I don't know what the problem is. What I do know is this situation is a pain in my a$$!! Thanks for the info...Cup

  4. #4
    Join Date
    Feb 2013
    Location
    shenendoah valley,va.
    Posts
    2,431
    is it not idling good or the engine just sputtering , missing , etc. i'm not a good motor man , but i know when my twin cylinder b and s vanguard would start running bad ...in most cases if i took the top of the carb off and unscrewed the main jet and blew it clean with carb cleaner , after that it ran great . a small piece of crud is all it takes sometimes . maybe this will help . jboy

  5. #5
    Join Date
    Nov 2019
    Location
    Illinois
    Posts
    106
    Quote Originally Posted by john swenson View Post
    is it not idling good or the engine just sputtering , missing , etc. i'm not a good motor man , but i know when my twin cylinder b and s vanguard would start running bad ...in most cases if i took the top of the carb off and unscrewed the main jet and blew it clean with carb cleaner , after that it ran great . a small piece of crud is all it takes sometimes . maybe this will help . jboy
    You can't possibly know less about motors than I do . To answer your question...after some work I did to the heated throttle cable the idle was a hair high, excessive gas fumes and intermittent surging. Cable tension was a hair tight so I adjusted that which lowered the idle a little bit but not enough. Also have a longstanding after fire issue that needed to be addressed as well so I decided it was time to retune the carb which I've successfully done in the past but can't seem to now. The air fuel mixing screw doesn't seem to be doing anything when I turn it which isn't correct I know that. May have to rebuild it again or do it later and buy a new one for now. Thanks for the advice JB...Cup

  6. #6
    Join Date
    Feb 2013
    Location
    shenendoah valley,va.
    Posts
    2,431
    good man .. i love putting motors on things but troubleshooting them i let someone else tackle if the few simple things i try don't work . jboy

  7. #7
    Join Date
    Nov 2019
    Location
    Illinois
    Posts
    106
    Decided to order a new carb altogether because I just flat out didn't feel like messing with the one I have now any longer. Figured I could swap in a new one and rebuild the original one later when I had more motivation. Well...I ordered the wrong carb which wouldn't have happened if the accompanying info and pics were correct so I'm back to square one. To make matters worse finding a new/correct carb isn't as easy as I thought. Not one that's not ridiculously expensive anyway. I've found a few that are like for like to what I have now but they're $200 and up!! Seems like a year ago or something like that I could get the one I need for way less but maybe I'm wrong. Is there a company out there that has more reasonable prices on carbs and gaskets etc? If so please chime in. Thanks...Cup

+ Reply to Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts