2 different '83 rotors

[Jimustanguitar]

I'm upgrading to the dual front discs and have both '83 rotors sitting on the bench. They're stamped with 2 different letters and are 2 different part numbers on the exploded view... Don't worry, I'll put the right one in the right place, but is there really a difference?

Perhaps a slight offset that I should be aware of for reassembly?

[Rikugun]

I'm not aware of an offset. Are the slot edges chamfered on only one side making an "inside" and "outside"  on a left and right rotor such that the slots spiral in the same direction when installed? Never had one in my hand so this is a guess...  :P

[motoracer8]

 Looking at the microfitch, they both have the same part no. 28v-25831-00-00 But from 3/82 there was a new pn.
28v-25831-10-00.

I have 2 pair of 83 disc, look the same to me.

[Jimustanguitar]

The Yamah-motor.com website says both:
Part Number: 28-V2583-10-00
Part Number: 28-V2583-11-00

Where is the fiche you're referring to? I'm curious now :) maybe it was superseded.

[Rick G]

Mt rotors  were torched by the previous owner ( they came from the Vision racer)  so I got  a set from a '85 Virago, fit right on , but there not drilled.

[motoracer8]

 Rick, the microfitch I have a dealer gave me, it's dated Jan 7, 1983

There may be newer ones I don't know.  I've tried looking up parts on Lightspeed, the system the M/C business uses, and have found many small parts not even in the system that are on the microfitch.

Honda did the same thing a few years ago, it does'nt say pn### is deleted, it looks like it never exsisted.

[Rikugun]

  the microfitch I have a dealer gave me, it's dated Jan 7, 1983 There may be newer ones I don't know. 

I agree and there may be many revisions. I looked at one (from Roro?) "Canada Australiasian 83 model parts fiche 28W" that I remember showing 2 numbers. The difference could be a simple as detail paint or no paint or slots or no slots. Maybe inventory was later standardized to one type and number?

[zore]

http://m.yamaha-motor.com/PartsViewer.aspx#%2fYamaha%2fXZ550RK_-_1983%2fFRONT_BRAKE_-_CALIPER%2fXZ550RK_%281983_MOTORCYCLE%29%2fFRONT_BRAKE_-_CALIPER_%28XZ550RK_-_1983%29

Looking at that, it appears there may be a left and right.  There appears to be a 1 and 4 with the part numbers you listed.  It's possible that the difference is for the ABS sensor  ;D

[QBS]

What ABS sensor?

[Rikugun]

Didn't your '83 come with ABS!!??  Man, you got ripped off!  ;)

[QBS]

I really hate it when that happens.

[zore]

My bad.  ABS was only available on the 82 with the stock rubber line.