OEM-GT #80 11 Tooth 3/4" ROLLER CHAIN IDLER SPROCKET. #80 roller chain idler sprocket. 11 tooth with 3/4'' bore. OD : 4''. Heavy duty percision bearing for longer life. Introducing the OEM-GT Heavy Duty 80BB15H Roller Chain Idler Sprocket! Designed for peak performance, this 11-tooth sprocket fits #80 chains with a 3/4" bore. Ideal for gokarts, its durable construction ensures reliability. #80 11 Tooth 3/4" ROLLER CHAIN IDLER SPROCKET. #80 roller chain idler sprocket. 11 tooth with 3/4'' bore. OD : 4'' Heavy duty percision bearing for longer life.