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  1. #1 Bike only starts if Carburetor insulator nozzle is open 
    C-Moto Not-so-Noob
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    Hi
    I had a Chinese 125cc ohv engine. It had some euro 2 standard device setup. There was an air pipe going from the carburetor intake manifold insulator to that euro 2 device.
    I swapped the engine with a water cooled 200cc Ohv bit that engine doesn't have that euro setup.

    Now if I use that pz27 carb with this 200cc engine it would only start of that nozzle on insulator is left open. If I close it engine will shut off. If it's closed and I try to start engine it won't start.

    But if it's left open it's sucking air and mixing it with the air/fuel mixture already meter by carb won't that lean it? It might injest water or dirt.


    It's that little black nozzle on the carb.


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  2. #2 Re: Bike only starts if Carburetor insulator nozzle is open 
    motor maniac ShuBen's Avatar
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    i guess that carb is simply too small for 200CC. Maybe try a PZ32 or even 34.
    SWM RS500R, R1200GS LC
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  3. #3  
    C-Moto Not-so-Noob
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    Quote Originally Posted by ShuBen View Post
    i guess that carb is simply too small for 200CC. Maybe try a PZ32 or even 34.
    Yes it not perfect size. But why is it starting only and only if that nozzle is opened?

    My understand is that that nozzle will further lean the air fuel mixture leaving the carb. And hence blocking that nozzle the bike should run even better m its acting as a sort of leak. But I m unable to find why is it not starting with that hole blocked.

    I have up up jetted the carb. Bigger Mj, pj, raised the needle in c clip.


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  4. #4 Re: Bike only starts if Carburetor insulator nozzle is open 
    motor maniac ShuBen's Avatar
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    you use a carb with too small cross section, additionally you give more fuel.
    The logic for me is the bike gets too less air. Check your spark plug if its black and or wet.
    Alternatively you can try to remove the air filter and test run it.
    Or you can try run the bike with removed connection between airfilter and carb to suck more air in.

    I have a small 125cc and when I open the choke fully it will die within short time after start.
    Then I have to close the choke about half and it will run again.
    The conclusion is that the relation Fuel to air is not correct. -> too much fuel
    You have too less oxygen available to burn the fuel.
    SWM RS500R, R1200GS LC
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  5. #5  
    C-Moto Not-so-Noob
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    Quote Originally Posted by ShuBen View Post
    you use a carb with too small cross section, additionally you give more fuel.
    The logic for me is the bike gets too less air. Check your spark plug if its black and or wet.
    Alternatively you can try to remove the air filter and test run it.
    Or you can try run the bike with removed connection between airfilter and carb to suck more air in.

    I have a small 125cc and when I open the choke fully it will die within short time after start.
    Then I have to close the choke about half and it will run again.
    The conclusion is that the relation Fuel to air is not correct. -> too much fuel
    You have too less oxygen available to burn the fuel.
    This can't be die to too much fuel. As the carb is from a 125cc engine. No serious jetting is done on it. Except that a big bore was installed on 125to male that 150cc and this carb was running perfectly on that.

    Tried with air filter removed still isn't starting. Not even for a fraction of a second.

    This engine with this carb and jet settings are used by other guys and is a common swap.




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  6. #6  
    C-Moto Not-so-Noob
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    Thanks I resolved it. Seems like the idle adjustment screw was out too much.. Don't know how that happened as just removed the carb and manifold from head and immediately installed on the 200cc non euro head..

    Seems like that screw would create some vacuum and let the slide move up..

    I shut that hole by inserting a screw

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