anyone experiment wit power valve spring tension

[redrooster310r]

wondering if it can be stiffened up with shims....has anyone done or heard of this?

[jon370r]

Yes, I have done it before. I made a small adjustable insert to go inside the ESR powervalve. Only made a slight difference on the dyno when adjusted from max to min of about a 3/4" preload on the spring. The powercurve moved down by about 200-400 RPM with more load on the spring. Nothing that I could feel while out riding.