Spring washers are common on Japanese bikes. They are very cheap alternatives to lock-nuts although less efficient it seems.
Japanese vintage motorcycles, JIS screw, small head nut, small head bolt, pan head screw, honda, Kawasaki, Yamaha, Suzuki, Kawasaki 900 Z1, honda 750 CB K, Yamaha 350 rd, Suzuki 750 gt, zinc, stainless, acorn nut, black zinc, Japanese industrial standard, JIS screwdriver, engine bolt, flange bolt, 7 mark bolt
Spring Washer
We have spring washers in sizes #1 thin, #2 standard most common, #3 thick and strong, Small used with small head bolts or nuts.