Does anybody know what the power now valve does?? I looked at it from motosport.

Is that the thing you insert in your carb? Don't wasted your money...

Yea.. It says major improvement but i don't see how

Power Now works OK on a 250F, but doesn't do much for a 400/450. With the 250F, the carb is much bigger relative to the bore size than on the 450, and the cam grind much more aggressive, and part throttle performance from off idle to about half suffers "some" because of it. At those throttle levels, there's a considerable amount of turbulence generated by the incoming air slamming against the closed face of the slide, and that contributes to the instability of the air column moving over the main nozzle. The PN works by dividing the air column in half, reducing the area perpendicular to the air flow. Does nothing at higher throttle openings, just cleans up the part throttle stuff.

We had one on our 250F, and we thought it helped quite a bit. A friend had one on a 426 and saw no improvement at all, but then, it ran fine without it, too.

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