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Just recently got my dads old bike running again.  Its a 76 kz900 built by Klaus Speedworks in Houston, TX in the 90s.  Rebuilt the carbs and it fired right up.  I've never ridden an old dinosaur that pulled this hard.  Pulls hard all the way to 12k at that.  Kind of bitchy riding around town below 3500 but I figure that's mostly the cam.  She isn't the fastest thing on the road, but she sure turns alot of heads. 

Looks like a cool old skool hot rod 

Welcome to a great forum. 

Keep red line at 9k rpm…unless it’s had all the mods internally to rev it higher but even with all the proper mods only good for 10k rpm.
keep , ride and enjoy 

Sweet ride. It would be nice to know what has been done to the engine. As Spdygon wrote, 10,000 rpm is usually plenty. As the rpm goes past 11,000 the crank bearings begin to slide rather than roll. (Yes, the crank uses roller bearings rather than plain bearings.) When that happens, they begin to gall, then BANG!