by Andrew Goodman
Got a modern motorcycle? Like the performance more than the running costs? Rather spend £400 on a shiny end can than on a valve clearance check and adjustment? I bet you would. But not so fast cowboy! What do valves do, why do they need checking and what happens if you skip an inspection or three? The most common question from motorcycle owners is “should I bother checking my valve clearance?”An internal combustion engine is a marvellous thing, it’s been around for a hundred or so years, and it’s in a well developed state of evolution. An internal combustion engine acts like a pump, internally driven by means of controlled combustions of an energy rich fuel / air mixture. Through a combination of momentum (flywheel and crankshaft inertia), and explosions (bangs from the cylinders) a four stroke engine sucks in fresh air/fuel, compresses it, explodes it, and then pushes the burnt exhaust gases out the exhaust pipe.