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1983 GSX250 idle problem

Discussion in 'Suzuki 250cc Twins' started by gainey, Feb 19, 2015.

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  1. gainey

    gainey Active Member

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    Hi everyone
    I have a gsx250 1983 model that has been sitting in a guys shed for 20 years until I came across it and thought I can clean the beast up. so far not to bad, he cut the wiring, no front brakes, rear shocks gone, front forks dry, intake orings gone, speedo not working etc etc.

    My problem is this, I have to constantly rev the throttle to get it going and when it does go in idles extremely high, even with the choke off, and if I lower the idle it will work for and few seconds and then races back up.
    I have had the carbs cleaned and checked by a bike shop, we have put new exhaust tips on and replaced the orings on the inlet to the carbs off the motor.
    The next step is to check the petcock unless anyone has a better idea, its like its starving for fuel???

    Also does anyone have a copy pdf of the manual, or knows the tappet heights (ithink that's what their called) and what the setting screws are on the carbs (how many turns in or out), and I also need to know how much front fork oil to put in.

    Thankyou for your help
     
    gainey, Feb 19, 2015
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  2. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Sounds much like the trouble with our FZR's at the Fizzer Factory. We are investigating worn needles and emulsion tubes & will see if replacing them helps.
     
    Linkin, Feb 19, 2015
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  3. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Welcome Gainey,
    Was it free? :)
    Hanging idle is too lean. Blocked pilot circuit or mixture screws wound in too far are two of the possibilities.
    With a bike like that you just have to work through the issues and recondition all the bits and pieces. But you probably know that already.
    cheers
     
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    maelstrom, Feb 19, 2015
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  4. Murdo

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

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    :welcome:
     
    Murdo, Feb 20, 2015
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  5. gainey

    gainey Active Member

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    Thankyou everyone for the input. Does anyone know which way the tubes go on the carbs for the 1983 invade I have one the wrong way ie.vacuum fuel etc
     
    gainey, Feb 20, 2015
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  6. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    GreyImport, Feb 20, 2015
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  7. Willrcr15

    Willrcr15 Well-Known Member

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    Hi & welcome, what do the plugs look like after you've had it going/playing up ?
    If theyre clean & dry like maelstrom said sounds lean sucking air somewhere or a carby issue or setting. Wet & black is too much fuel & unburnt, is she hard to get going from cold, should be if it's lean.
    20 years in the shed, she'll be an interesting adventure but worth it in the end.
     
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    Willrcr15, Feb 20, 2015
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  8. gainey

    gainey Active Member

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    We put new plugs in her but I will check what they look like
    What do you mean by a blocked pilot circuit ?
    Where do the tubes invent above pic go for numbers 77 & 75
    Thankyou again
     
    gainey, Feb 20, 2015
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  9. gainey

    gainey Active Member

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    image.jpg image.jpg I took a picture of the wiring can anyone see if I have it right as it was cut for some reason I wonder if it is causing the idle/ starting problem
    All the lights and blinkers work now though image.jpg
     

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    gainey, Feb 20, 2015
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  10. Murdo

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

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    How does that compare with the wiring diagram?
     
    Murdo, Feb 21, 2015
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  11. gainey

    gainey Active Member

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    Compare to the diagram I think I have it but the green and white wire I can't find where it goes
     
    gainey, Feb 21, 2015
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  12. Willrcr15

    Willrcr15 Well-Known Member

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    Not sure but 77 looks like the bowl vent / overflow & 75 maybe the petcock vacuum line, has it got a vacuum actuated cock on the tank? if there should only be the one line. There should be 2 77 lines, one from each carby
    She looks pretty clean from the pics, gotta be happy with that.
     
    Willrcr15, Feb 21, 2015
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  13. gainey

    gainey Active Member

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    I checked the pet cock it has two lines one for the fuel and one for a vacuum
    I took the cover off the vacuum side and saw under the spring a worn rubber which is letting fuel come down the vacuum line
    So i plugged the vacuum line coming out of the carby and off the pet cock and it fired right up so I guess now if I leave them plugged it should turn the pet cock into a normal one????
    So does that mean that on is now off and the prime is now on can someone clarify that
     
    gainey, Feb 21, 2015
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  14. Willrcr15

    Willrcr15 Well-Known Member

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    She sounds like it was sucking fuel down the vacuum line & straight into the inlet manifold & the fuel flow past the vacuum valve would have been restricted maybe, thats a good find & easy fixed.
    You now are relying on the needle & seat holding back the fuel just like on most bikes but you can't shut the fuel off.
    On is on & prime is on now. If your a purist then get a new vacuum valve assembly kit & put it back to original.
     
    Willrcr15, Feb 22, 2015
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  15. gainey

    gainey Active Member

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    Thanks will, u pulled the fuel line off the petcock any turned it to on and nothing came out but I turned the valve to prime and fuel came out .... Strange but it works and idles good so it won't matter if I use the prime as my fuel on then it won't flood the carbs?
     
    gainey, Feb 22, 2015
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  16. Willrcr15

    Willrcr15 Well-Known Member

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    Ok, sounds like the vacuum valve is holding but if it's perished best to replace it when you can, all good then, the prime will do for good fuel flow, good to hear she's running well, fuel down the vacuum line & into the head would have been ugly as far as metered fuel to the engine.
     
    Willrcr15, Feb 22, 2015
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  17. gainey

    gainey Active Member

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    Hi everyone, i thought i had the idle issue sorted but no luck, the bike will start and then once warmed I adjust the idle to around 1 - 1500 rpm, and then like in the video




    ()

    it will shoot up , if I put the choke on it goes up and then drops, we cannot seem to get it sorted.
    I have had the carbs looked at by a bike shop and they said they look ok. We have since put high temp silicone on the backside of the carb boot connecting to the motor around the orings, we then also put black silicone around the actual carb boot.
    We have put on pods, but we have taped up at least half if not more of the pod so it doesn't get to much air, and we have different exhaust tips on it.
    Any suggestions?
    we are stumped, our next thing we are thinking is maybe we look at replacing the diaphragms on the carbs - but even when we looked at them they looked ok?
    and we are also thinking maybe we check the valve clearances..... any help would be great.

    Also does anyone know where I can get the diaphragms from?
    And has anyone checked their valve clearances and what do we need to look for and how to check the settings?

    thankyou again
     
    gainey, Mar 15, 2015
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  18. kiffsta

    kiffsta Senior Member

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    Mick Hone is good for Suzuki spares http://www.mickhone.com.au/

    Is there a chance you can run with the standard tank, petcock and airbox ? That will help you eliminate where the issue lies
     
    kiffsta, Mar 15, 2015
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  19. gainey

    gainey Active Member

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    hi kiffsta

    We tried it with the original air box and tank but it did the same thing.
    The peacock has a vacuum line to it and we found that fuel was going down that line due to the orings and the oneway valve inside the petcock we ruined so I have ordered a new set. We put a new battery in the bike but now cannot fit the original airbox back in so that's why we have gone with pods.
    We have put tape over half each of the pods to reduce the amount of air being sucked in .
    It used to rev a lot higher on its own so what ever we have done its has come down but it still jumps back up
     
    gainey, Mar 16, 2015
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  20. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Become a Premium member and access the manual re the valve clearances.

    Have the carbys been overhauled completely?

    Have u set the pilot/mixture screws ?

    If things arnt stock u will be chasing your tail.

    As for bike shop mechanics ... they wouldn't know if their ass was on fire , let alone anything about old bike carbys.
     
    GreyImport, Mar 16, 2015
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