Awhile back i picked up a 2000 cr250 all the main stuff was in good condition but it needed alittle tlc. The first thing i check was the power valve and you guessed it it was not opening all the way, far enough to open the exhaust flap but not enough to close the subs and carboned up worse than anything i ever seen. fixed the power valve and help others on hear to get thiers straight. Mine i felt like it had to be reved out alittle farther than a 2001 i had a few years back and the hit was not that strong compaired to a 2004 rm250 the last 2 stroke i had. So i was going to test pre loading the power valve. I turned the pinion shaft clockwise (closed for the pinion) and the linkage valve counter clock wise for closed. i adjusted the lingage alittle off of closed, if you look at it there is a hole for a pin stop to hold it when working on it and on the other side it has a like tear drop mark so i put the tab on the linkage valve on the front edge of the tear drop mark, it made the L mark just off to the open side by about guessing 2 to 5 mm. you had to hold a straight edge to see it was off any. now what i have is the power valve open just tad early probally just enough to take the play out from 11 years of use. end result no loss bottom, alittle harded hit and just a touch sonner just what i wanted. I may have noticed a little sound differance at the end of the muffler but didn't have a before and after to compare.