I am fast approaching that time when one should have the valvestem clearances seen to. I don't know exactly what it involves but its something to do with checking the tappet clearance or something relative to the valve stem end thingy. My question: what happens if i leave it for longer than the recommended service interval? I'm asking because I (try to) do all maintenance work myself. What does one actaully 'fix' when doing a tappet clearance? i know it has someting to do with the cam shaft but i don't understand why. Isn't the cam shaft lobes always in contact with the tappets?, so why does that need to be a clearance gap for the valves? Going to a mechanics is tha very last thing I want to do. I'll learn before I give it to someone and throw money at them to make the problem go away. My bike is an 06 VTR-250 currently with 11K on the odo and bought secondhand from a dealer with 4K on the odo with only one official service. I so far have done; many chain clean+reoils, oil+filterx2, brake pads F&R x1, radiator flush x1, carby-cleen-juicex1, new tyres F&R (balanced at shop, however). I want to learn how to "do valves". I know how an engine works and all that, also. In the future I'll be doing an air filter change (very soonish since my fuel consumption is creeping up: 3.8L up from 3.5L/100km), will do my own clutch plates replacement and further down the track a chan+sprocket replacement.