MxNewb

the spark plug came installed new, air/fuel mixture screw is the one to adjust if its running rich?

I've uploaded images of the spark plug after riding i think it's too rich ?

In warm weather you often don't need the choke to start bike engines. If you close the choke then it's running too rich to fire up in warm weather, so just fire it up with the choke open. I don't understand why you want to close the choke once the engine is warm - that will cause it to run too rich which is why it won't idle. Once an engine is warm you leave the choke fully open. The problem is I'm not sure you're referring to open and closed the right way round in the first place - hence the query about the captions on the photos. Open - means that the choke flap is fully open so airflow is not restricted. Closed - means the flap sits across the airflow so restricting it. Less air mean the air-fuel mix is made richer for cold starts. yes i was confused about the choke open/closed positions and now i understand it all makes sense haha what a newb i am, Thank you so much for helping

the bike won't start with the choke closed but will start fine with choke open but when the bike has warmed up if i close choke engine will stutter then shutdown unless i give it continuous small amount of throttle to keep it idle/running with choke off is it bad for to start the bike with choke fully open ? rather than choke closed for start up ? Thanks all for helping

i will get more pics of the spark plug it gets darker sooty colour when riding the bike

Hi Can someone please confirm if the choke positions are correct ? also the fuel/mixture screw and idle adjustment screw pics below the spark plug on the bike gets really black sooty from what i've read it's running too rich? too much fuel ? pitbike is wpb 125cc race, carburettor is Jing ke Pz26 - 5k Thanks for helping