Knocked about

摘要

When I was but a callow youth, I volunteered to "help" a Mend who had just bought a Yamaha TD1-B, which was that company's 1965 250cc production roadracer. My project was to increase compression and thereby, I fondly hoped, increase power as well. What I got was detonation, in the form of sparkly nibbling at the outer edges of the piston crowns and cylinder heads. Detonation is an undesired form of combustion that results from heat-driven changes in the fuel-air mixture as normal combustion proceeds. It typically attacks the outer edges of pistons and heads because it occurs near the very end of combustion.