I’ve used 2-1/2 Lb. weight lifting weights painted white with a bushing to make the hole 3/8″ and my take is that they take up allot of space and look like crap. If you make bushing for these kind of weights make sure you put a heavy washer that covers the original hole or the bushing could pop out from vibration. Don’t put more than 5 Lbs. on a 5/16ths bolt. If you mount more than 5 Lbs. on one bolt go up to a 3/8″ bolt.
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience