you will also need a clutch perch and a cable.. if this is for an ATV/quad then no doubt it will have a hydraulic rear brake master on the bars and will make fitting and operation of the clutch lever to the bars very difficult..
125's are same lol.. and id be amazed if you had a true semi auto 125cc engine. usually there 110's with 125 barrels. lol the 125 and 110 barrel are same size too.....