125 cc 4 stroke motor engine cdi pit dirt bike atv quad for honda crf50 z50 usa note installation manual is not included professional installation is highly recommended product function description specifications type single cylinder, 4-stroke with air-cooled, and clutch operated by hand bore×stroke 52.4×55.5 mm displacement 119.7 ml compression ratio 9.01 max power 6.5 kw/7500r/min±375r/min rated power 5.6 kw/7500r/min±375r/min max torque 8.0 nm/5000r/min±250r/min idle speed 1500r/min±100r/min min fuel consumption =367g/kw.