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Help VM30 Mikuni on Honda 250 single

Discussion in 'Honda 250cc Singles' started by stephen mitchell, May 28, 2020.

  1. stephen mitchell

    stephen mitchell Member

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    Hi guys I am hoping someone here may have already gone down the path of jetting a Mikuni VM30 (Not VM32) on a single 250. I have a VM30 and a few jets etc as per below but the bike its was off was an 1100 so more than likely too rich,
    2 x needles and jets:
    6F5 (needle jet for this in the carb I have not removed it yet)
    6DP4 with needle jet 166-Q2
    4 x main jets 195,200,250,330
    2 x pilot jets 025,030
    I was hoping mikunioz would be helpful but it was like I asked them for the winning power ball numbers, because it wasn't an variation they had int he system they really struggled to give me a starting point which was disappointing. Yes I can go straight to a VM32 for a starting point for an extra $200plus dollars but I thought I would use the power of knowledge on the internet first :)
    fingers crossed cheers steve
     
    stephen mitchell, May 28, 2020
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  2. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Welcome to the forum.
    The only issue with using a carby off another bike is the jetting could be changed to suit that bike, compared to the Mikuni factory jetty for that carby
    To use it you may need to change everything back to standard VM30/32 spec's and tune it from there, may need to change the air jet, slide (throttle valve), slide needle (jet needle), Needle jet (emulsion tube) main and pilot jet's, also possibly the float level
     
    my67xr, May 28, 2020
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  3. stephen mitchell

    stephen mitchell Member

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    Yes I am expecting to do that, however there is no factory setting for a mikuni vm30 on a single 250, I am after a starting point where someone has already had a shot at this, failing that I will start some trial and error with what I have working on the basis that I am too rich on main jet and needle/jet and dial back when/if I order more jets etc.
     
    stephen mitchell, May 28, 2020
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  4. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Latest Mikuni VM30-83 Specs

    Standard Jetting Specifications Main jet (VM4/042) 250
    Pilot Jet (VM22/210) 40
    Needle Jet P-5
    Jet Needle     6F5
    Throttle Valve 2.5
    Air Jet     2.0
    Needle Valve 3.3
     
    my67xr, May 28, 2020
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  5. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    As always, try it (it may be closer than you think) and see what is needed before buying any new jets.
     
    Murdo, May 28, 2020
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  6. stephen mitchell

    stephen mitchell Member

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    Ah cool this is what I was chasing over the phone this morning, I am not sure why it was such a mission, now I can start to play and move from there, really appreciate it cheers
     
    stephen mitchell, May 28, 2020
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