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Thread: Baja 90cc Carb Tuning

  1. #1
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    Baja 90cc Carb Tuning

    I picked up my son a Baja 90cc atv for a good deal and in great shape but I need help with the carb.
    The atv fires up nice with the choke but will not idle with out it being closed. As soon as you open the choke it need throttle to stay alive.
    Any help?
    90 YJ. 4link F/R, 16" SAW Airshocks, 32bolt Beadlocks, D60/14bolt, Full Hydro/Hydroboost L67 3.8SC 700r4 NP231/D300
    02 Yukon XL on 37's DD
    91 Cherokee Juggy scrapped for Greener Grass
    I prefer to build it and not buy it, you see it, I probably made it.

  2. #2
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    Pull the carb apart and clean all the jets. Your pilot jet is clogged and more than likely a few more. Depending on how badly it is clogged get some good carb or combustion chamber cleaner and soak everything overnight. Take some stranded electrical wire and use individual strands to clean out each jet. Once you get it cleaned and running right run some carb cleaner through it for a few tanks.

  3. #3
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    Thanks. Had the little guy running through the swamp yesterday and it has no lack of power just won't idle until it's been running for 45min or so. I'll try this.
    Amazing thing is it looks identical to his friends Yamaha 50cc fairings and all. Frame is different but the Baja has lights, hydro brakes, and ifs. Pulled way better too. But I disconnected the rev limiter so in the mud he could get 10x the wheel speed and could climb hills no probably.

  4. #4
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    The fact it will idle when hot after 45 mins indicates a lean condition at idle when cold which backs up the plugged / restricted idle jet.

    If it will run and you can live with it for now just keep giving it a dose of carb cleaner with every tankful. Try Lucas upper cyl lubricant, carb cleaners from wherever etc. Sometimes it will clean itself out with cleaner alone. Sometimes it needs manual cleaning. Wish I could be more helpful.

  5. #5
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    Nope. Thanks. Pulling the carb and giving it a good bath is no problem. Already had it off once.

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