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I got an old 82/83 750Spectre awhile back and I’m looking to rebuild my KZ650 motor. I’m wondering if these are the same as the GPZ cams. I had read that the two bikes shared cams one year. Thanks 

No they are not the same as the same year GPZ750 cams, they have less lift and less duration.

Since the Spectre is more of a cruising bike they chose to run milder cams than those found in the sport bike. They are not far off the GPZ cams, I am not 100% sure but I think 0.50mm less lift, the nose profile is more of a peak than the broad GPZ profile (I have both Spectre/GPZ cams but have not done a complete analysis)

Those cams would still be a good upgrade to a KZ650 motor especially if you slotted the cams sprockets and spent some time dialing them in. Just be aware that the exhaust cam does not have a tach drive gear.