The 500 had more engine than it did frame also, in my opinion. It had a problem at speed top speeds and being a two stroke, the upper end needed attention at about 13,000 miles after the life it was made to live in.I had a74’ 900 Z1, bought it a year old from a friend when he got a new Norton. He’d put after market headers on it. It was a screamer, a gorgeous bike but not the most stable approaching top speed, the *** end would like to wobble. Long time ago