I purchased this bike brand new in 1973. It was January and the dealer had not sold any yet. After purchasing it I was in contact with Pop Yoshimura in California who recommended a kit which I purchased for about $300. U.S. The kit boosted the 903cc engine to 1033cc´s and came with an oil cooler. Other than that it looked stock. Needless to say this engine far outweighed my expectations. With the extra horsepower I was able to tear up all the roads in my area of the woods. 0 to 60 was just under 4 seconds and it topped out at about 142ish. Back then this was unheard of. The bike would go through rear tires and drive chains in a heartbeat. The chain technology had not caught up to it, and they were the most expensive thing about owning this bike. In subsequent years I added Koni shocks and that helped a lot. Handling never was an issue. The first Z1´s had shorter swing arms I believe and it made for a rougher ride. I have owned other motorycles since then, but none surpassed the sheer excitement of riding this beast.