I still find it difficult to believe a 500 Vincent is that competetive against other 500 race bikes of the era........Most other high end Brit singles put out more than 40 HP. The ESO speedway engine I ran in mine before the engine change put out 45 straight out of the box. It is very difficult to extract bigger HP from a single.......Mine is a 665 cc putting out 48.2 HP and still does not have enough especially in the unlimited class.........I sent my head away to a friend who is installing bigger titanium valves and modifying the seats and ports.....we are changing the seat angles to 50 Degrees and running beehive springs........ratio the rocker assembly...... I am aiming for 0.550" lift larger inlet valves and smaller exhaust.......We have worked out that basically the valve train in a Vincent is quite poor for developing big HP figures ......the use of roller symetrical cams and ratio rockers is the answer, but unless you have a better oil pump system, you will be waisting your time, Oh and stronger pushrods and everything else to go with it........Upon disassembly of my head recently, I found the valve stem collars were very worn.........The rockers themselves were fine, but the collars had not........possibly from not being hard enough, also I am going to increase the flow of oil to this area of the head much more once the modified head comes back.......My head is one of the latest types of the 600 kits that Terry was selling........this with the chambers and ports fully CNC'd.......Apart from matching the port to the inlet manifold, I had done no other mods to it........It was a good starting point, but now the fun begins........Who knows if it will survive.
