Engine will only start if the nozzle in intake manifold is open

[chamjiee]

I had a Chinese 125cc ohv engine. It had some euro 2 standard device setup probably air suction valve thingy.. 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 intake manifold .

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[AntNZ]

at a guess I would say it needs the extra airflow to run..., have you tried blocking it off and adjusting the air/fuel screw to compensate?

 

[motodevo]

Try to open the throttle a little with that hole blocked and start it. If it starts, with the air cleaner off look into the carb, if there isn't a gap at the bottom of the barrel, wind in your idle adjustment screw so there is about 1mm-2mm gap,you can block off that hole and it should run. Adjust your idle to suit and your good