Quote Originally Posted by Mach 1.5 View Post
Hi Mick. Back in the early 80s Venom would use the piston from the HW50 and use it in their HW55 conversion. As the 55 piston was to lite. Hope that helps in someway? Regards Mach 1.5
Quote Originally Posted by BTDT View Post
The HW50 piston weighs 186 gm, the HW55 163 gm. The HW55 piston head is aluminium, and extends back into the piston, giving available length for the compressed mainspring of 95.6mm in the 55, against 108mm in the 50.

I suspect that if Venom used the HW50 piston in their 55, it was as much for the extra spring room as the mass.
Brilliant information.