Laurent question: when I want to start I have sometime kick back, is this normal ? Thank you
UPower: To start an engine it need some practice.
1/ Look for the compressure point
2/ Pass it slowly
3/ Leave the kick lever back up
4/ Move down violently the kick lever. It need to give the maximum of speed to the engine.
If you don't do like that, specially with long stroke engine or cubic more of 125 you can brake the crankcase.
CDI must be a model with low ignition timing at startup especially if the engine are bigger than 125 cm3.
If ignition timing is adjustable it should be adjusted to the minimum
Throttle must be closed when we kick. Can accompany a little but only when the engine is hot. Not more than 10 ° opening the throttle in any case.