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Thread: 85 big red jet

  1. #1
    Join Date
    Feb 2010
    Location
    Jackson, NC
    --
    106

    85 big red jet

    85 big red carb I am rebuilding is missing a jet. I have done hundreds of these carbs and never seen one missing the small jet. I have the pilot, I have the main but the little jet beside the starter jet is missing and it isn't even threaded to accept one.
    Attached Thumbnails Attached Thumbnails image.jpg  

  2. #2
    Join Date
    Feb 2010
    Location
    Jackson, NC
    --
    106
    First hole is the position I am talking about

  3. #3
    Join Date
    Aug 2014
    Location
    South Louisiana
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    1,915
    I'm pretty sure that a little rubber plug goes in that one. Flyingw would have more info. He is somewhat of an 250es ninja.
    "Roll on 3"

    RIP Ol' Deuce

    "Long Live the ATC"
    Building: ATCr125x
    Riding: ATC200sx
    "I am not a mechanic, mechanics get paid for this. I do it because I enjoy it."

  4. #4
    Join Date
    Mar 2010
    Location
    Pacific NW
    --
    4,255
    Does it have a Keihin number on it
    like QA 01 or similar?
    Some have plugs there and later, plugs into the side of that jet stack.
    I can try to look at one tomorrow if you can get a # off yours

  5. #5
    Join Date
    Feb 2010
    Location
    Jackson, NC
    --
    106
    It's a qa 04. Is the tiny jet not used?

  6. #6
    Join Date
    Feb 2010
    Location
    Jackson, NC
    --
    106
    The other 2 85 carbs I have done had all 3 jets.

  7. #7
    Join Date
    Mar 2010
    Location
    Pacific NW
    --
    4,255
    not to be a wise guy but did it run the way it is now?
    Been so long I forget but even trying to get info from Keihin directly was
    like musical chairs and I distinctly remember getting absolutely nowhere.
    Almost time for flyingW to chime in, I hope.
    I have one to do right now and at this stage of my life, I HATE surprizes.

    do parts diagrams from servicehonda or bikebandit help at all?
    I guess I'll be looking at those before my next autopsy and will
    report back if I find anything of interest.

    sn: so you didn't find a rubber plug rolling around in the float bowl?

  8. #8
    Dustin87R is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    May 2007
    Location
    Maysville, Georgia
    --
    192
    I just rebuilt the carb on my 86 and it was the same except it had a rubber plug inplace of the jet.

  9. #9
    Join Date
    Feb 2010
    Location
    Jackson, NC
    --
    106
    It had an extremely high idle like 2500 probably. There is no rubber plug. 86 up had the plug and a starter jet in the side of the pedestal. The 85 isn't suppose to have a plug. I'm telling you this thing is weird. It also never had the updated vent hose kit. It started cold like a champ though.

  10. #10
    Join Date
    Jan 2011
    Location
    Choctaw, OK
    --
    2,755
    The QA04A carb is off of the 85 TRX250. The primary jet is not used on the TRX. I have tried to run the TRX carb on my mockup and on my SX and they don't run very well unless the intake is partially blocked restricting air flow.

  11. #11
    Join Date
    Feb 2010
    Location
    Jackson, NC
    --
    106
    Well I'll be. That is awesome flyingw. Thank you for the info. I have another carb. I'll check the other carb number.

  12. #12
    Join Date
    Jan 2011
    Location
    Choctaw, OK
    --
    2,755
    If you have an 01A, 02A, 07A, or 08A, you're good. The odd numbers are ES and even are SX. Any one of those carbs will work on any year ES or SX. They all interchange. The 04A is not a good replacement for the ES or SX.

  13. #13
    Join Date
    Jan 2012
    Location
    Austin, Massachusetts
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    1,591
    guy is a carb jedi
    Wubba Lubba Dub Dub!!!!!

    TRIKES:
    86 250r
    85 250sx
    86 250sx
    84 Yamaha 225DX - Bruins Trike
    85 Yama 225DX - The Rental!
    150cc Piranha powered 70
    110cc Lifan 70
    82 70
    83 ALT 50 Trail Buddy
    88 Yamaha BW 80
    84 z50

  14. #14
    Join Date
    Feb 2010
    Location
    Jackson, NC
    --
    106
    Man you have a wealth of knowledge. So someone has "tinkered" with this beauty before apparently. I am curious how you found out this carb info. Any manuals or service info?

  15. #15
    Join Date
    Jan 2011
    Location
    Choctaw, OK
    --
    2,755
    Here is my tutorial on rebuilding these carbs.

    http://www.3wheelerworld.com/showthr...54#post1257154

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