All of you guys say change oil alot and check valves every 20 hours and some people say they are still on stock valves. Well even if you do check the valves every 20 hours they can still go out of spec. what the point in checking clerences when you know that once you shim them the first time your not gonna get more than 10 hours out of the top end? I still check my clearence all the time but it doesn't make sense.

if you stay on top of it and re-shim them when needed they can last alot longer than that, i check my valves about once a month, and if they are even a little out of spec or to the maximum allowed tolerance, i will adjust it. on this schedule i have ran stock valves in every one of my crf's and only had to replace them 3 times in 3 years, and the first time i was new to the 4 stroke and let them go pretty bad

WNYRyder_05 said:

I think the idea is to have an idea of where your valves are to avoid an engine failure that will cost mucho $$.

like mikerides said if you watch them then it will give you a heads up if your engine is a ticking time bomb or not. Also if you dont know your valves are going south in a hurry and then you go blow 600 bucks on that exhaust you saved up for months for, then what are you gonna do, out of cash and out of a bike.

Valve check IS preventive!! alot less than engine rebuild.

and it only takes a few minutes so why not?