Immensely strong but heavy four with dubious handling, although most now have upgraded suspension and brakes (Z1’s disc crap). Engine tough, runs for 75 to 100,000 miles; clutch, gearbox and camchain most likely to go. Unlike smaller Z fours, has roller bearing crankshaft and gear primary drive. Make sure that 4-1 exhausts are matched with jetted carbs, otherwise pistons and valves melt. Immaculate Z1’s fetch serious money but chassis modded Z900’s make much more sense