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Help 1988 Honda vtr 250 idle climbs when warm

Discussion in 'Honda 250cc Twins' started by ericfx1984, May 19, 2018.

  1. ericfx1984

    ericfx1984 Member

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    So I just got done rebuilding the carburetors. Bike seems to start up. However I noticed after the bike warms up the idle starts to climb. I set it at about 1400 RPM. But by the time the bike reach is operating temperature the idle is closer to 4500 or even 5000 RPM this is even after turning the choke off. The only way I have been able to lower the idle after the bike is warmed up is to turn the idle down on the carburetor. The problem is at that point the bike doesn’t want to start. My guess is that something is opening up as it warms up causing increased airflow Which of course raises the idle
     
  2. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    Air leak between the carburetors and rubber joints to the cylinder head potentially - spraying with brake cleaner can aid in locating the source of the leak

    Otherwise that's an idle jet setting being too lean

    or it's a combination of several elements
     
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  3. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Yeah check for air/vacuum leak's on the intake manifold's, as they age they'll develop small hairline crack's that can let air in.
    Did you sync the carby's after rebuilding them ?
     
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  4. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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  5. Mike Fulcher

    Mike Fulcher Active Member Premium Member Contributing Member

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    I would agree with the previous comments, very likely an air leak between carbs and cylinder head.
     
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