If your motorcycle is in bad conditions, your bike will reflect by different color of smoke. There are three kinds of smoke we can see in our daily life:
If your engine exhausts blue somke when it works, there maybe another phenomenon appears together: your engine oil consumpts very fast. It is caused by the too much engine oil, the low compression pressure than standard, abrasions in piston or cylinder.
When the engine works, you can see black smoke exhausted from fume, and smell a slight smell of gasoline. The reason may be: the mixture of gas is heavy concentration, the spark plug is in bad condition, and the ignition time is later.
The fuel and the cylinder or muffler contain water. If there is a white smoke phenomenon, it is indicated that the fuel is not qualified and the quality of the fuel should be replaced. It will disappear after the normal operation, if only the white smoke is taken when it is started, . This problem is a normal phenomenon.