Carburetor? Spark plugs?

[Elefant60]

Hello everyone

I picked up my G12 CSR 1959 from the seller today. Initially it ran smoothly, but after about 30 kilometers it started to stutter and almost stopped several times. I suspect it's the carburetor. As soon as the engine has cooled down a bit I'll check the spark plug pattern. Both candles are completely covered in soot. Which would mean that the carburetor is set too rich. Can someone help me?

Greetings Robert

[g80csp11]

If you are not familiar with the bike , is there anyway that you have not opened the choke lever
tight cable is choke in the running position

[Elefant60]

I know this from my other vintage motorcycles. Yes, the choke cable is completely pulled.

[Andy G]

Before you adjust anything, I'd suggest you replace or clean the plugs and run again.
If it starts and runs fine before stuttering again, then you have something consistent to fix.
Unless you put it there, I would replace the fuel..someone else's old fuel is unpredictable and sometimes has two stroke oil in it!!
As this bike is new to you, I wouldn't just dive in and start changing things....one step at a time and test after every change.
First check for me would be float bowl. Check float is leak free (hot water method), moves freely, and the valve is effectively controlling fuel entering. There is a method to test that fuel is entering to the correct level by using a loop of clear hose, but I'll let you google that.
If that is all fine, then it's time to take the top off and check position of the needle. Try lowering one notch.
If that doesn't fix, then you'll need to check the carb has the right jet and slide, so it may be worth taking carb off for a fuller strip and clean.
Sometimes previous owners do odd things, like correcting for an air leak by adjusting a carb to run rich, but that's all the fun with a new purchase?!

[Elefant60]

Thank you very much for your feedback. I will check these points.
Greetings Robert