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'84 GSX 250

Discussion in 'Your 250cc Projects' started by Evo, Mar 10, 2015.

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  1. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Fitting pod filters, different exhausts and altering airboxes, what really happens? An excellent technical article from the 1983 edition of Cycle World. http://www.litetek.co/docs/InSearchOfFreeLunch.pdf
    and the pilot jets they refer to
    [​IMG]

    Ben has done it the right way by fitting a pair of Keihin CR carbs.
     
    maelstrom, Sep 2, 2015
    #21
  2. Evo

    Evo Well-Known Member

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    Maelstrom, I understand your frustration when it come at to people like me ( read that as amateur). I have read that artical before and read it through again twice tonight and now have a very good understanding, I think of it.

    I am in no way doing these modifications to trying to squeeze every last bit of power out of the bike. To be honest pods look so much better than a air box and that is one of the reasons I am doing this. The other reason is to learn how thing work and the effects that changes to intake, needles, jets and the like have.

    As I said not looking for ultimate power will be happy just is it runs and I feel at this stage I am on the right track to do this. I could be wrong and will find out when I get it on the road

    Totally agree that Ben is doing it the correct way wit the Keihin but at this stage I'm not too keen on spending more on a new set of carbs that would cost more than what I have spent all up on this bike including purchese price
     
    Evo, Sep 2, 2015
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  3. Evo

    Evo Well-Known Member

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    Removed the plugs and cleaned the up then started it and let it idle for 5 min it was sitting around 1200rpm and didn't give it any more revs. Then removed the plugs and they were black as in carbon. My take on this is too rich or just the fact it was sitting at idle for soo long.
    As for a flat spot it seemed to be alright and fairly responsive up to 8K
    Have to remember that this was with the bike sitting on the stand. Might be a different story when there is some load on it.
    I did take a vid of it might post in the next day or two.
    Anyway how's your bike going Ben?
     
    Evo, Sep 2, 2015
    #23
  4. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    That's ok. I just bang it up now and then for the benefit of anybody reading. Not meant to be a critique of what you are doing.
    If I were doing a GSX250 'cafe with mudguards' I would want to bin the air box for the same reason as you. But there is very little in the way of alternate slides, needles and needle jets for OEM CV carbs. Ben bought the full blown racing smoothbores. However, you can just buy a pair of VM Mikunis, they are not expensive.
    [​IMG]
    For a budget build this would be my weapon of choice. I wouldn't bother trying to re-jet CV carbs. VM's are easy to jet and very functional. The hardchromed slides last an eternity as well.
    cheers
    Blair
     
    • Like Like x 3
    Last edited: Sep 2, 2015
    maelstrom, Sep 2, 2015
    #24
  5. Phil

    Phil Senior Member Contributing Member

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    Now that's sound advise :thumb_ups:
     
    Phil, Sep 2, 2015
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  6. Murdo

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

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    So after reading through that article from 1983, I have learnt a bit more about air filter resonance and why it effects CV carbs so much. Thanks Blair.
     
    Murdo, Sep 3, 2015
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  7. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    maelstrom, Sep 3, 2015
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  8. Murdo

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

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    Thanks Blair.
     
    Murdo, Sep 3, 2015
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  9. Evo

    Evo Well-Known Member

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    So it been a bit since I have updated but lots has happened. Played around with the jets in the carby (I'm sure there will be a few people on here shaking there head) and have it running ok. My guess is that it is a bit rich but at this stage I'm happy with it.
    Finished of a lot of bits and pieces mainly electrical but also checked over all the nuts and bolts.

    Then got rego on the bike and took it out for its first ride. Very happy with how it went. Only went for a couple of quick laps around the block but everything seemed to work as it should. In the next couple of weeks I'm going to take it down to my local bike shop for them to do a quick check over and compression test. Fingers crossed for this

    This is the point where I wanted to get to before I did any of the cosmetic work or start to replace parts so I wasn't wasting money on a dud bike. So things to look at now
    Exhaust
    Swap over tank
    New seat / seat hoop on frame
    Paint
    Look into new carbys
     
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    Evo, Dec 5, 2015
    #29
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