Complex sentence: The YZ 125 has had a liquid-cooled 124 cc since 1981, case-reed, 2 stroke engine since 1981, the models from 1974-1980 were air-cooled and also 2-stroke.
Split into simpler sentences: The YZ 125 has had a liquid-cooled 124 cc, case-reed, 2 stroke engine since 1981. The models from 1974-1980 were air-cooled and also 2-stroke.