I seem to be forced by circumstance to bore out the 350cc to be a 500cc.... the current set up is a long conrod which allows a triumph 650cc twin t120 piston . It has a compression height of about 26mm which is the same as a Honda 400 XR. Hence I am experimenting with the possibility of 85mm X 88mm giving the 500cc dimensions of BSA Gold Star . However I am very conscious that I do not have the breathing capabilities that machine has/had. However I am looking forward to the weekend of 12/13 August for the GB memorial sprint at East Kirkby. ...it has become a sprinters version of the Goodwood revival.