i have a 400ex and its in need of a valve adjustment. i remember hearing a few things about valves. i just can't remember if you will gain a little topend or lowend when the valves are a little loose. i think you should gain in the opposite area when you have then a little tight. the bike is stock besides air box mods and a pipe. thanks

 

If they say .004" to .006", I set them at .005". I don't buy there is any significant gain by varying the clearance within the specs. If anything, I guess performance wise it would be better to go tight as the valves are open a little longer, but too tight and presto burno valve. Also your valve is then that much closer to the piston, increasing the possibility of interference.