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Honda bf 50 bystarter low volts

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  • Honda bf 50 bystarter low volts

    I have a 2004 honda bf50a that I just bought. Seems to idle a bit rough and a little fast, about 1400 rpm. Top plug was black and slightly wet, mid plug was a little cleaner and not wet, lower plug was fairly clean. I suspected the bustarter on the top carb. Checked resistance, about 24 ohms, supply voltage was about 8 volts. It does get warm and motor starts cold fine. I turned the idle down to 1000 and motor runs ok ,a little rough at idle, and seems to shudder when accelerating from a long idle. My question, is 8v normal to the bystarter I read about someone else having around 7v but didn't find out if this was normal.

  • #2
    A bustarter?

    If it's running rough, there's a 99% chance it has to do with the carbs. A thorough internal cleaning is a good place to start.

    I have no idea where you are checking your voltage and getting 8v. The wire leading to the battery should have the same voltage the battery does.


    • #3
      That auto corrected. Should say bystarter or auto enrichment valve or se valve, essentially a type of choke. Supply wires to it come off of ecm. Read a post saying it should be 12v, read another saying it measured 7v didn't find out if that was too low to close it all the way. It has a heater that expands and pushes a needle down. Low voltage might just take longer to close or it might not close completely. If I can rule it out then I'll go after the carb.


      • #4
        Your engine may be a little newer than an '04. The '04's I see are still equipped with a conventional choke. That's part of what was throwing me off. I've only played with a couple of those, but if I remember right you can adjust the height of that pin. If you have voltage and the heating element is warming, I wouldn't mess with that side of the equation.

        You can check to see if that valve is closing by plugging the vent hole it gets it's air from. It's on the front of the carb, just inside of the carb mouth. If I remember right, that carb is the only one with this vent hole. The others don't have it. It can easily be covered by your finger with the engine running. With a warm engine, it should make no difference in the way the engine runs when plugged. If it does change, you have something going on there. Either you didn't wait long enough for it to warm, or it's not sealing properly.
        Last edited by ahicks; September 12th, 2019, 06:55 AM.


        • #5
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          Great thanks, I'll check it out.