Bolt restoration?

Joce, There has been some good info in this thread and some info I personally don't agree with. The black bolts at your tire store will rust within 24 hours. I buy more fasteners than most anyone on this forum and if the fastener is black, it is just plain steel and rusts super-quickly. At least try zinc plated which will also rust in time. FEW of the fasteners on a bike are "critical"... brake, engine mount and a few others might be considered critical but certainly not the bolts holding your battery box or clutch cover. While it doesn't hurt to use 8.8 grade bolts everywhere, your battery box or clutch cover won't fall off if you use aluminum or stainless.

As for the stuff recommended by Ron, I can't say. Give us a report on how it works. I would certainly use a wire brush wheel to clean each fastener and then would be curious as to how the addition of this stuff effected torque or even fit of a bolt.

I bead blast all the hardware and have it zinc plated like original or if you need it to be black you can have it black oxide coated. It all needs to be baked a 350 deg F for at least 3 hours after any exposure to acid to prevent hydrogen embrittlement.