New Drive Sprocket - trouble With snap ring

I need to replace my sprockets to suit the track I’ll be racing at. When reassembling I’m having trouble securing the small sprocket to the crack. The snap ring won’t go back on without making the crack hard to spin (no longer spins freely) it did before with the old sprocket. Old sprocket is black , new one is gold

Any I missing something here ?

Sounds like you may need a different shaft bearing or remove a spacer. I know when IAME changed there clutch drum and drive sprocket combo, they added a rubber o-ring to eliminate the free play. The older one was slightly wider I think. You may want to check with the manufacturer whether something similar is true for this set up.

Check to see if you have thin thrust washers on the “drive hub” of the clutch. These should be on the drive hub shaft, between the drive hub body and clutch drum. How many of these washer are in place? Not 100% sure of what clutch that is, looks like a Premier

Do you have a dial calipers? Measure the widths of the two sprockets from the retaining clip groove to the outside edge of the gear.