Clutch Basket Rivet Repair
I use a tapered head Allen bolt and a special tapered
"nut" on the reverse side I manufacture on my lathe. I did this to all the
Yamaha TZ's I have, because the clutch basket isn't available separately in TZ
speak, but the YZ125 wet clutch has the same basket for a lot less than the
whole TZ part, and with the screws, I can replace baskets killed by the rider
tipping the bike over at a lot less cost, and no need to hunt up, or manufacture
new rivits. I just toss the gear and other parts from the YZ hub.
If you have a friend to help you hold the hub while performing the operation, you can invert the clutch hub with the fingers pointing downward, with each rivet sitting on a large round drift larger than the rivet head in a vice, on each rivet, one at a time, and then, hammer the other end of the rivet standing up, down, tightening it.
This may, or may not tighten the front to rear, or side to side play in the hub. The rivet just holds the outer holder plate to the clutch hub, they don't cushion the hub to the primary gear. If you were to take the clutch hub apart, the rivets are holding a set distance between these pieces, with a dowel around the rivet.
There is a donut of rubber elastomer over the dowel, and into the primary gear, making for a cushion for the primary gear to the clutch hub. Sometimes, these are OK, but they can also compress and get loose in their primary gear holes. The elastomer donuts are not available separately. Be aware, you might not get the cushion tight with just the rivet tightening operation.
If you will just be drag racing the bike, then I'd replace the elastomer cushions with ones made of steel, and completely eliminate the cushion altogether.