ok sounds dumb but i come from a mod cars. and used to have to get my rotors turned often depending on how much i raced.  sooo do you turn a motorcycle rotor? ever?

im about to put my katana front end on and i want to know if i should have to rotors turned and then i relized i don't even know if you turn a motorcycle rotor

Nope, they can't be turned.

I've heard of guys blanchard grinding theirs with moderate success.  That's the way they're made in the first place, but the heat cycling causes hard spots to develop.  The result can be a rotor with "nodules" that stick up above the rest of the surface.  Rotors are made from pre-ground plate, grinding the finished rotor is a quick way to turn it into a pretzel if you can't keep the heat out.

Also, there is very little wear allowance on a motorcycle rotor to allow for grinding.

In general, the only time I would ever fuss with rotors is:

1)  They're not made any longer.

2)  I had a blanchard and some free time.   

No we dont.
If its not 4mm thick, its garbage. Some places used to sell the rotor wear part only, you swap the rotor with the pins they give you and reuse your center part (also called a hat - cos it looks like one) ... however I dunno where to buy em. Kat rotors last a lot longer than GS rotors, and usually its a good idea not to swap rotors from side to side if they have any use on them. That is why rotors have L or R stamped on them. They have L or R ... not L on the left and R on the right. Depending on what and when and why and how and what not, only 1 had a stamp usually.
If swapping side to side or throwing on rotors that have no markings on them, I'd be very attentive to them the first few 100 or so miles. I'd avoid it like the plague still, the rotors if reversed in wear direction can gall and chunk up and disintegrate ... cos metal stresses in 1 direction and when load is reversed, it will bow and buckle. The same principle you use to break a thin sheet at a given location by bending back and forth. Its also called load reversal.
Cool.
Buddha.

sweeeeet thats all i needed to know i have to find the L and R stamping now

Quote from: The Buddha on September 12, 2008, 09:35:20 PM
No we dont.
If its not 4mm thick, its garbage. Some places used to sell the rotor wear part only, you swap the rotor with the pins they give you and reuse your center part (also called a hat - cos it looks like one) ... however I dunno where to buy em. Kat rotors last a lot longer than GS rotors, and usually its a good idea not to swap rotors from side to side if they have any use on them. That is why rotors have L or R stamped on them. They have L or R ... not L on the left and R on the right. Depending on what and when and why and how and what not, only 1 had a stamp usually.
If swapping side to side or throwing on rotors that have no markings on them, I'd be very attentive to them the first few 100 or so miles. I'd avoid it like the plague still, the rotors if reversed in wear direction can gall and chunk up and disintegrate ... cos metal stresses in 1 direction and when load is reversed, it will bow and buckle. The same principle you use to break a thin sheet at a given location by bending back and forth. Its also called load reversal.
Cool.
Buddha.

+1 bazillion and a monkey