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Help Mikuni VM 26 on GSX250

Discussion in 'Suzuki 250cc Twins' started by Evo, Jan 20, 2016.

  1. Murdo

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

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  2. Evo

    Evo Well-Known Member

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    How much influence should the idle screw play? I'm a bit unsure as to where this should be "set" when trying out new jets.
    In my mind it should have zero to very little effect like 1 turn max

    Was thinking of having idle screw 1/2 a turn in (from nothing) and air mixture 1turn out when testing new pilot jets. Thoughts?
     
  3. Murdo

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

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    The idle speed screw will have to be adjusted in enough to keep the engine running.
     
  4. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    @Evo
    I sent you an important link in a conversation. Did you get that?
     
  5. Evo

    Evo Well-Known Member

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    Yes got it. Will have a look tomorrow
     
  6. Clancy1

    Clancy1 Well-Known Member

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    Make Model
    Suzuki GSX 250E
    Year
    1980
    Engine
    Air cooled, four stroke, parallel twin cylinder, DOHC, 4 valves per cylinder
    Capacity
    249

    Bore x Stroke60 х 44.2 mm
    Compression Ratio10.5:1
    Induction
    2x 30mm Mikuni BS30SS
    Ignition / Starting
    Electronic / electric
    Max Power
    29 hp @ 1000 rpm
    Max Torque
    2.2 kgf-m @ 8000 rpm
    Transmission / Drive
    6 Speed / chain
     
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  7. Clancy1

    Clancy1 Well-Known Member

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  8. Evo

    Evo Well-Known Member

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    Yea your right. Not sure where I got 45from. Do remember it was a quick Google search. Must have been for an across or the GSXR. I did think it was a bit high at the time
     
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  9. Evo

    Evo Well-Known Member

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    So it has been a bit. Between working long hour 6days a week and landscaping / paving the back yard there hasn't been much work on the old girl.
    This is where I an at.
    Out the box they had 60 pilot and 180 main. Got it running but cloud tell it was way too rich at idle. Didn't even bother to giv it revs as I thought that I should sort out the pilot jet first.
    Not having any experience I didn't know how much difference a drop in jet size was going to achieve so got a 50 pilot. Still way to rich.

    Was a bit stumped as to what to do from here as I was going to need to spend a small four tune on jets to work this out. Was about to take it to the local shop for them to do it but decided to email mikunioz.com to see if they had any ideas of where to start. Thankfully Tom there pointed me in the right direction. So I placed an order for main, pilot and the sizes each side of the pilot

    Put in suggested jets and and with a bit of playing round with air and throttle screws and seemed to run, sound and smell ( exhaust) fine. Played around with the other pilot jets but went back to the first ones

    So at this stage, sitting in the shed at idle and revs it seems that the magic numbers are 20 (pilot) and 150 (main). Still a lot of playing around to do and of course actually riding it but I feel that I am on the right track. Finely.
     
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  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Well done! All progress is good progress.
    Once you have finished you will look back on this and think that it wasn't so hard after all. Just some trial and error. Don't forget the slide cutaway, it makes a big difference.
    cheers
    Blair
     
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  11. frankie2sheds

    frankie2sheds Member

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    Hi Evo hope your still an active member and can point me in the right direction. New member 6/6/2022
     

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