What is that clattering noise when starting up, sometimes loud and sometimes not at all? Is that a problem? Can it be quieted down?
The noises you are hearing are normal. there is quite a bit of clearance in the starter gear cluster and other connecting parts, and what your hearing is the slap and backlash of the gears, connecting rod, piston, and other internal parts. I understand your concerns, these sounds (clunks) can be very loud at times but rest assured that these are present in this type of motor.
I have taken apart my Lifan 200 motor (loud clunker) on two occasions and all is well.
Buyingchina