Excellent analogy barossi73.
It's not just the port height which is changed by the powervalve. The area under the left powervalve cover is part of the exhaust system at low rpms and cut out of the system at high rpms.
Munch,
I asked which model you have because, depending on year, there are things other than the powervalve which can change the power delivery characteristics to a harder hitting delivery. (these items will also have compromises in other areas of operation)
Some examples of what I'm referring to are:
On older models with the Boyesen Rad Valve the Power Reeds can be replaced with Pro Series reeds, carbon fiber reeds. Our first experiment, back in 1997 was to install the Pro Series reeds for a '99 Honda CR250. It gave the bike an instant hit.
Installing a MC silencer or a FMF motocross silencer (no spark arrester and very short).
Replacing the right side flywheel weight with the aluminum crank shaft spacer that comes on the MC250. This would remove 7 oz of flywheel weight.
The RB designs head mod made a huge difference in the delivery of my 2006 DE300.
Different year and model cdi boxes will have different ignition curves.
What year and model are you running?
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