primary sheave?

[snow3]

I have a primary sheave for a yamaha, it has the numbers 8ca00 on the sheave, it is the inside half toward the motor. Does anyone know what it is off of? the hole in the center where it threads onto the other half is larger than on my viper primary, if this helps any.. Thanks,

 

[snow3]

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[SRXfromHELL]

yamaha list 8ca as an alternate clutch for a 96 vmax 600 mountain max
hope that helps