On this parts fiche the Bolt(8x21) is the most specified component.
A sample from the products for the Front Wheel (dl650ak7/ak8/ak9) include: Axle,fr, Tire,front,110, Wheel,front(19, Weight,wheel Balance 10g.
The lowest price component in this Front Wheel (dl650ak7/ak8/ak9) parts-list fiche is the Bolt.