1st Valve adjustment was a success!

[Badbob]

Engines need a bit richer mixture when they are cold. That is what the choke is for. Needing a little choke to idle while its cold is not a malfunction.

Having a single cylinder air cooled engine the GZ250 is a bit temperature sensitive and is not very tolerant of misfires. If the engine is not up to normal operating temperature and you push the choke to the off position the mixture will be leaner, the idle speed will be slow, and the chance of misfire higher. If it misfires the engine will stop.

The colder it is the colder the engine runs. If you ride in cold weather (below 40) you may notice that the idle speed tends to fluctuate with the temperature.

Not changing the spark plug at the prescribed intervals may also increase the number of stalls when the engine is cold.