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Message: [QUOTE="SpeedyManiac, post: 1150772, member: 19453"] Yes, you are right. I've been thinking about it and have a tough time explaining powervalve function as I'm not completely sure on its workings. Rich can probably give a better explanation. Here's my understanding though: The powervalve is used to widen the powerband on two-strokes. It operates by changing the exhaust port size at a certain RPM. At low RPMs, a smaller exhaust port means more power, but once the engine gets to a certain RPM, the powervalve opens, increasing the exhaust port size, letting more exhaust gases flow out faster, increasing power. There is a jump in torque when the bike opens the powervalve, so you feel a 'hit.' Non-powervalved two-strokes are generally peakier (a feel like they hit harder) because the bikes run poorer than their powervalve equipped brothers. When they start running well (exhaust port size is matched to RPM, engine load and throttle position), they come on strong. So, in summary, I may be wrong saying the powerband starts when the powervalve opens. It depends on the individual bike. Sorry if I'm not making sense, spent most of the day in class, then working on homework, then fixing up some pictures for some photo contests and stuff, and then I came to check DRN. My brain is toast at the moment. [/QUOTE]