Vf500 acceleration issues

Discussion in '1st & 2nd Generation 1983-1989' started by Marz_y, Sep 30, 2024.

  1. Marz_y

    Marz_y New Member

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    So I’m having a issues where when you give the bike any throttle that’s more than just a smidge it sputters and doesn’t want the revs to climb the issues got to me today while riding where it died when I tried to come out of a stop and would start again so probably a parasitic draw somewhere aswell
     


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  2. RogueRC24

    RogueRC24 Member

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    I did have similar issues which turned out to be reg/rec with both my CBR600 and RVF400
    . But you can never discount carb issues in my mind.
     


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  3. Colddevil

    Colddevil Member

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    My brain went pilot jet immediately from that description.

    I'm curious though since I'm fighting an issue on another bike that I'm suspecting electrical on... (twin) Fires up perfectly, 30 seconds of choke, choke off, runs perfectly for 10 minutes at idle. I can ride it around the neighborhood briefly and it runs fine. As soon as I get to about 15 minutes, it starts firing on one and eventually just dies.

    Or, it does 7/8 of a lap at Road America and starts sputtering on the front straight. I was able to able to keep it running for the remainder of 9/8 laps to get it back to pit lane and then it cut out when I pulled the clutch in to turn into the paddock. Wouldn't refire. I had to push it a long way home. Refired about 20 minutes later which is consistent with what it was doing in my garage. I measured the battery and it was at about 15.0-15.1V at idle and dropped to about 14.7 with throttle applied.

    I was suspecting one or multiple of coils going out sensitive to heat, float height, or tank venting issue. However I have no idea what the symptoms of a bad R/R are. How did you diagnose a bad R/R?
     


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  4. squirrelman

    squirrelman Member

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    ^^^ by testing the stator AC output first to rule it out as the problem. if stator is good check that r/r output is about 13.5-14.5 volts at battery terminals @ 5000 rpm. check both cold and hot.
     


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  5. Marz_y

    Marz_y New Member

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    What should be the stator ohm readings out of the three yellow wires
     


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  6. squirrelman

    squirrelman Member

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    forget ohms, just make sure its not shorted to ground. instead, measure AC voltage @ 5000 rpm between all 3 combinations of yellow wires. all should be 50-60 ACV. just like the service manual says.
     


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  7. Marz_y

    Marz_y New Member

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    Bike doesn’t want to even crank now I’ll check once I get that sorted
     


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  8. RogueRC24

    RogueRC24 Member

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    Dead batt?
     


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  9. Marz_y

    Marz_y New Member

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    Nope brand new and charged it all last night
     


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