If anyone is interested in the sound this is my old 270 Rephased XS650 powered custom motorcycle:
The XS motor in the bike is equipped with a 270 degree re-phased crankshaft and a billet camshaft, plus a high ratio primary gear set and clutch assembly with the machine work being performed by Heiden Tuning from the Netherlands. The cylinder head porting work was done by Gary Hoos Racing, uses 2mm oversize Inconel Alloy valves. The motor is also equipped with a Mikes XS 750 big bore kit and myriad of other performance parts from both Heiden Tuning and Mikes XS. Ignition chores are handled by a 270 degree re-phase Pamco Ignition System and a Sparks Three Phase charging system keeps everything running. Various engine parts both internal and external were sent to Performance Coatings for thermal and ceramic engine coatings. In choosing to make the bike very period correct, most of the sheet metal and the running gear required extensive reworking to fit the custom built XS650 hard-tail frame and motor combination. A set of custom made header pipes was also fabricated for the project that flow into a set of modified Big Twin 36 to 40 style mufflers. The XSLA project features 18 inch black Big Twin Star Hub wheels with stainless steel spokes, Avon Safety Mileage tires, Edart front and rear Disc Brake conversion kits and Jay Brake master cylinders for both of the front brake and hydraulic clutch controls. The rear brake control assembly is fitted from a 58 to 69 Big Twin FL and the hydraulic clutch conversion uses a slave cylinder assembly from a Honda VFR.