67
Cylinder, piston, piston ring failure: the fuel contains gum or wear
Air intake pipe leak: use time is too long
Excessive carbon deposits on intake and exhaust valves and pistons:
poor fuel quality and poor oil quality
Clutch slip: poor oil quality, long use time, overload
Cylinder block and piston ring wear: poor oil quality, long use time
Brake separation is not complete: the brakes are too tight
Chain too tight: improper adjustment
Engine overheating: The mixture is too rich or too thin, and the
quality of oil and fuel is poor.
There are obstructions etc.
Improper spark plug gap, normal 0.8-0.9 mm
Air intake pipe leak: use time is too long, adjust or replace
Cylinder head or valve leak