on the engine piston cylinders at the top under the head end there is a spring/spacer thing between the alloy of the finned cyl and the steel sleve its self. can any one tell me what it is and does, is it needed? i've taken the engine apart and one of the cyls, this spring thing are all in bits and broken falling out all over the place.
please help, no one here in NZ can help me? thanks.

Hi Jon.....Bob here. I have an XV920RH. A couple of years ago I renewed the rings. At that time I used aftermarket head gaskets (those springy things you wrote about). The aftermarket gaskets are not the same as the genuine Yamaha ones. Using the cheaper aftermarket gaskets cost me a head, as the front cylinder gasket failed and scoured out a large area of the head. The Yamaha gaskets look like inner and outer copper rings with a grooved ceramic material between. Spend the extra $$$ and get the Yamaha gaskets.
Bob